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THE EFFECT OF AN ACL INJURY PREVENTION PROGRAM ON GLUTEUS
MEDIUS STRENGTH BETWEEN GENDERS
A THESIS
Submitted to the Faculty of the School of Graduate Studies
and Research
of
California University of Pennsylvania in partial
fulfillment of the requirements for the degree of
Master of Science
by
Jordan Blair
Research Advisor, Dr. Shelly DiCesaro
California, Pennsylvania
2011
i
ii
ACKNOWLEDGEMENTS
I would like to take this opportunity to thank
everyone who made this thesis possible.
First and foremost
I would like to thank my advisor Shelly DiCesaro.
Without
your constant help, I would not have made it this far.
I
would also like to thank Tom West for taking a chance on
student from The Rock.
Without your help and encouragement
throughout this year, I would probably still be sitting in
your research methods class.
Thanks are due to Dr. Edwin
Zuchelkowski as well for your encouragement and belief in
my abilities to complete this study.
My whole committee
deserves to be recognized for placing an unprecedented
amount of faith in me and for allowing me to perform a
study that was something I truly wanted to do.
I would also like to thank my classmates and
additional faculty at California University of
Pennsylvania.
It was a long year, but definitely one that
has yielded friendships.
Additionally I would like to
thank Regis Visconti and Emily Obenauf for their assistance
during my study.
Special Acknowledgment is due to Troy Baxendell for
the inspiration for this study.
Thank you for your
continuous support not only for this study, but for me as a
iii
professional.
I am proud to call you a mentor as well as a
friend.
Finally I would like to thank my family and my
girlfriend for their endless support.
would not have direction in my life.
Without all of you I
I love all of you.
iv
TABLE OF CONTENTS
Page
SIGNATURE PAGE. . . . . . . . . . . . . . . . . i
AKNOWLEDGEMENTS . . . . . . . . . . . . . . . . ii
TABLE OF CONTENTS
LIST OF TABLES
INTRODUCTION
METHODS
. . . . . . . . . . . . . . . iv
. . . . . . . . . . . . . . . . vii
. . . . . . . . . . . . . . . . . 1
. . . . . . . . . . . . . . . . . . . 4
Research Design
. . . . . . . . . . . . . . . 4
Subject . . . . . . . . . . . . . . . . . . . 5
Preliminary Research. . . . . . . . . . . . . . 6
Instruments . . . . . . . . . . . . . . . . . 6
Procedures
. . . . . . . . . . . . . . . . . 7
Hypotheses. . . . . . . . . . . . . . . . . . 9
Data Analysis
RESULTS
. . . . . . . . . . . . . . . . 10
. . . . . . . . . . . . . . . . . . . 10
Demographic Data . . . . . . . . . . . . . . . 10
Hypothesis Testing
. . . . . . . . . . . . . . 11
Additional Findings . . . . . . . . . . . . . . 13
DISCUSSION . . . . . . . . . . . . . . . . . . 16
Discussion of Results . . . . . . . . . . . . . 16
Conclusion. . . . . . . . . . . . . . . . . . 23
Recommendations. . . . . . . . . . . . . . . . 24
v
REFERENCES . . . . . . . . . . . . . . . . . . 26
APPENDICES . . . . . . . . . . . . . . . . . . 30
APPENDIX A: Review of Literature
Introduction
. .
. . . . . . . 31
. . . . . . . . . . . . . . . 32
Noncontact ACL Injuries
. . . . . . . . . . . . 33
Incidence . . . . . . . . . . . . . . . . . 34
Anatomy . . . . . . . . . . . . . . . . . . . 38
Anatomy Involved In ACL Injury . . . . . . . 39
Role of the Gluteus Medius . . . . . . . . . . 42
Difference between Genders . . . . . . . . . . 42
Mechanical Alterations . . . . . . . . . . . . . 48
Prevention Programs . . . . . . . . . . . . . . 49
Components
. . . . . . . . . . . . . . . . 50
Previous Results . . . . . . . . . . . . . . 50
Use of Prevention Programs . . . . . . . . . . 52
Summary . . . . . . . . . . . . . . . . . . . 54
APPENDIX B: The Problem . . . . . . . . . . . . . 55
Statement of the Problem . . . . . . . . . . . . 56
Definition of Terms . . . . . . . . . . . . . . 56
Basic Assumptions . . . . . . . . . . . . . . . 57
Limitations of the Study . . . . . . . . . . . . 57
Significance of the Study
. . . . . . . . . . . 58
APPENDIX C: Additional Methods . . . . . . . . . . 60
Informed Consent Form (C1) . . . . . . . . . . . 61
vi
IRB: California University of Pennsylvania (C2) . . . 64
Trunk Neuromuscular Training Program (C3) . . . . . 80
PAR-Q(C4) . . . . . . . . . . . . . . . . . . 107
Demographic Information (C5)
. . . . . . .
. . . 110
Subject Testing Sheet (C6) . . . . . . . . . . . 112
REFERENCES . . . . . . . . . . . . . . . . . . 114
ABSTRACT . . . . . . . . . . . . . . . . . . . 120
vii
LIST OF TABLES
Table
Title
Page
1
Demographic Data of All Subjects . . . . . 11
2
GMS difference between the Training and
Control Groups . . . . . . . . . . . . 12
3
GMS Difference between Males and Females in the
Training group . . . . . . . . . . . . 13
4
Dominant leg GMS Change between the Training and
Control Groups . . . . . . . . . . . . 13
5
Non-Dominant leg GMS Change between the Training
and Control Groups
6
. . . . . . . . . . 14
GMS difference between Dominant and
Non-Dominant Legs in the Training Group . . 15
7
Average GMS Difference Compared to Days
Missed . . . . . . . . . . . . . . . 15
1
INTRODUCTION
Anterior cruciate ligament (ACL) injuries have been
estimated to account from 75,000 to 250,000 knee injuries
per year.1
While this does not make it an epidemic, the
recovery time associated with this injury coupled with a
higher incidence rate among females makes it one of the
most ubiquitous injuries in the current athletic landscape.
Due to the nefarious reputation of ACL injuries, there has
been a copious amount of research conducted to advance the
prevention of non-contact ACL (NCACL) injuries.
Non-contact ACL injuries account for approximately 70%
of all ACL injuries that occur.
The etiology of non-
contact ACL injuries is still largely unknown, but a common
mechanism of injury is a valgus collapse at the knee.1
A
valgus collapse of the knee is characterized by internal
rotation of the femur, knee valgus, and ankle pronation.
The risk factors for this injury have been identified as
environmental, anatomical, hormonal, and biomechanical.2-4
Anatomical, biomechanical, and hormonal factors are
considered to be intrinsic because these are factors that
are within the patient.
Environmental factors are
considered to be extrinsic because they consist of factors
outside of the patient and, have potential to be
2
controlled.
These situations can range from weather
conditions to playing surfaces to types of shoes worn by
the athlete.
Analysis of studies on the incidence of ACL injuries
place female athletes at a two to six times higher rate of
NCACL injury when compared to males.1,4-7
Due to this
discrepancy, there has been an abundance of research
performed to find the cause of this higher incidence rate.
The results of available research point to five major
gender influences differences that seem to influence ACL
injuries in females, including anatomical differences
between genders,8 increased knee valgus angle,9-14 internal
rotation at the tibia,15 hormonal influences,16-18 and muscle
activation patterns.19,20
The gluteus medius has been
identified as one of the key muscles in the prevention of
patellofemoral injuries, and of the five major gender
influences, the gluteus medius is a factor in knee valgus,
internal rotation, and muscle activation.21
The identification of the higher incidence rates in
female NCACL injuries created a push for the development of
ACL injury prevention programs.
While there have been
multiple techniques used in the past, the most recent and
successful ACL injury prevention programs utilize
neuromuscular training.22-25
These programs implement a
3
combination of lower body strengthening and plyometrics
that improve gluteus medius strength and muscle activation
strategies while also improving the strength of surrounding
musculature.
The purpose of this study is to examine the effect of
a current ACL injury prevention program on gluteus medius
strength in males and females.
It is important to examine
if this program provides the benefit of gluteus medius
strengthening as well as attempt to identify if males and
females share similar gluteus medius strength gains from
the implementation of the program.
Previous research has
shown the need for hip abductor strengthening to prevent
NCACL injuries.9-14,22-25 Recognition of an ACL injury
prevention program’s effectiveness may lead to an increase
in the use of the program at all levels of athletics, which
in turn may lead to a decrease in the incidence of NCACL
injuries suffered by males and females.
4
METHODS
Research Design
This research study utilized a quasi-experimental pretest and post-test design using twelve male and twelve
female subjects between the ages of 18 and 26 who were
considered physically active.
Subjects were considered
physically active if they participated in physical activity
at a moderate intensity for 30 minutes at least 3 times a
week.
The independent variables for the study were gender
and ACL prevention program or control group assignment.
The dependent variable was gluteus medius strength.
Gluteus medius strength was measured using the Lafayette
Manual Muscle Test System (MMTS).
Results were compared
between groups to observe the effect between the program
and control group.
Results also compared the program’s
effect between genders.
Manual Muscle Testing System
(MMTS) pre-test measurement provided a baseline from which
effects of the program and control group were observed.
5
Subjects
The subjects consisted of 24 physically active male
and female college student volunteers between the ages of
18 and 26.
Participants were considered physically active
if they participated in physical activity at a moderate
intensity for at least 30 minutes three times a week.
All
subjects in the study signed an Informed Consent Form
(Appendix C1), a Physical Activity Readiness –
Questionnaire (Appendix C3), as well as a Demographic Sheet
(Appendix C5) prior to participation in the study.
Subjects were instructed to sign the Informed Consent Form
only if they had read through it, understood the study, and
had presented any questions to the researcher.
Subjects
were randomly placed in a study group so that there were no
more than half the number in the control group that was in
the experimental group.
Each participant’s identity
remained confidential and was not included in the study.
Participants who had been diagnosed with a lower extremity
injury within the past six months, identified through the
demographic sheet, were excluded from this study as those
with recent injury may not be ready to participate in an
injury prevention program.
6
Preliminary Research
Preliminary research for this study was conducted to
familiarize the researcher with the MMTS and to determine
the amount of time the muscle testing procedure as well as
the exercise program took to complete.
Two subjects, a
male and a female, were tested for gluteus medius strength
and then led through the ACL injury prevention program.
The researcher looked for the subject’s ability to
understand directions on how to perform each exercise and
the amount of time muscle testing took, as well as the
amount of time needed for completion of the exercise
program.
Instruments
The instruments used in this study were the Lafayette
Manual Muscle Test System as well as assorted exercise
equipment.
The Lafayette Manual Muscle Test system (MMTS)
is a handheld dynamometer that provides an objective way to
measure the strength of a muscle.
The reliability of
dynamometers has been reported as high.26
The following
formula will be used to determine strength of the gluteus
7
medius.
Torque=(Force in Newtons) x (Distance in meters),
Strength=(Torque/Body weight in kg)27
Procedure
The study began with the researcher holding an
introductory meeting with the participants to discuss the
requirements of the study as well as the procedures for the
ACL injury prevention program.
Subjects were informed of
the anticipated time frame for the study as well as the
amount of time the ACL injury prevention program would
take.
Subjects were then offered the Informed Consent Form
once all questions were answered and the researcher had
covered all aspects of the study pertinent to the subjects.
Subjects were then given a sheet to sign up for a time in
which baseline testing was performed.
Testing took no more
than twenty minutes and was done prior to the first day of
the experimental groups exercise session.
On the first day of the experimental group’s exercise
session, each exercise was demonstrated so that the
subjects were aware of proper technique and form.
Packets
with each exercise’s description and pictures were provided
to the participants to ensure an information source was
present if a subject was unsure of technique or form.
8
After the first exercise session, specific times for each
subsequent, were assigned.
Either the researcher or an
approved student from California University of
Pennsylvania’s Athletic Training Education Program, who was
trained in the proper techniques of the exercises, was
present at each session.
Attendance logs were also
maintained during the study to ensure compliance within the
experimental group.
Data from subjects missing more than
two exercise sessions or two sessions in a row were not
included in the study.
Post-tests occurred no later than
one week following each subject’s final exercise session.
Trunk Neuromuscular Training
The trunk neuromuscular training (TNT) program was
developed by Myer et al23 to focus on core musculature as
well as the hip stabilizers to decrease the risk of ACL
injury in females. The training sessions were conducted two
days per week for six weeks as per modified recommendations
of the authors.
25 minutes.
phases.
Each training session lasted approximately
The program consists of five progression
Progressions were implemented once a participant
demonstrated mastery of each exercise in a given phase.
Each phase consisted of 13 exercises that gradually build
in intensity.
Each phase followed the subsequent exercise
9
progression: lateral jump and hold, step-hold, BOSU
swimmers, DOSU double knee-hold, single leg lateral Airex
hop-hold, single tuck jump-soft landing, front lunges,
lunge jumps, BOSU double leg pelvic bridges, single leg 90
degree hop-hold, BOSU lateral crunch, box double crunch,
and Swiss ball back hyperextensions.
Since a warm up was
not specified in the program, a dynamic warm up consisting
of a slow jog for 30 seconds, toe walks for 10 yards,
straight leg kicks for 10 yards, leg swings for 30 seconds,
high knees for 10 yards, and butt-kicks for 10 yards were
implemented to reduce the risk of injury.
Hypotheses
The following hypotheses were based on previous
research and the researcher’s intuition based on a review
of the literature.
1. The subjects placed in the Trunk Neuromuscular
Training program will enhance gluteus medius strength
significantly more than the subjects placed in the
control group.
2. Females placed in the Trunk neuromuscular Training
Program will significantly increase their gluteus
medius strength when compared to males.
10
Data Analysis
All data was analyzed with SPSS version 19.0 with
significance set at an alpha level of 0.05.
The research
hypotheses will be analyzed using an independent T test.
11
RESULTS
Demographic Data
A total of twenty-four subjects (n=24, 12 male, 12
female) participated in this research study.
Two
participants were unable to complete the study
requirements, so data for twenty-two (n=22, 11 males, 11
females) subjects was analyzed for significance.
The
experimental group consisted of twelve subjects (n=12, 7
male and 5 female), and the control group consisted of ten
subjects (n=10, 4 male and 6 female).
All subjects were
volunteers that were physically active, as defined by the
American College of Sports Medicine as exercising at least
three times a week for thirty minutes per session at a
moderate to intense level, and had not suffered a lower
body injury within six months prior to the beginning of the
study. Demographic data, which is demonstrated in Table 1,
was collected by the researcher at the beginning of the
study.
12
Table 1.
Male
Female
Total
Demographic Data of all Subjects
Mean
N
Std.
Deviation
Mean
N
Std.
Deviation
Mean
N
Std.
Deviation
Right
Femur
Length
(m)
0.438
11
0.0318
Left
Femur
length
(m)
0.437
11
0.0313
Weight
(kg)
80.08
11
16.266
Age
(yrs)
21.73
11
1.902
0.412
11
0.0158
0.412
11
0.0152
67.06
11
12.72
20.82
11
1.834
0.425
22
0.0279
0.425
22
0.0273
73.57
22
15.729
21.27
22
1.882
Hypothesis Testing
Statistical analysis was performed on data from all
twenty-two subjects that completed the study with
significance set at an alpha level of ≤ 0.05.
All final
means were measure in Newtons.
Hypothesis 1: The subjects placed in the Trunk
Neuromuscular Training program will enhance gluteus medius
strength (GMS) significantly more than the subjects placed
in the control group.
independent t-test.
Hypothesis 1 was tested utilizing an
Average GMS comparing the experimental
group to the control group found that there was a
13
significant difference between the means of the two groups
(t = 2.697, p = 0.016).
The mean GMS difference of the
experimental group was significantly higher (m = 0.0618, sd
= 0.02257) than the mean of the control group (m =
0.0057, sd = 0.01077).
-
This is displayed in Table 2 below.
Table 2: GMS difference between the Experimental and
Control Groups
N
Mean
Std. Dev.
Sig. (2(Nm/kg)
(Nm/kg)
tailed)
Training Group
Control
Hypothesis 2:
12
10
0.0618
-0.0557
0.02257
0.01077
p = 0.016
Females placed in the Trunk
Neuromuscular Training Program will significantly increase
their gluteus medius strength when compared to males. The
independent–samples t-test was calculated comparing the
mean scores of males in the experimental group and the mean
scores of females in the experimental group.
No
significant difference was found (t = -0.665, p = 0.527).
There was no significant difference between the mean GMS
difference of males (m = 0.0489, sd = 0.06312) to the mean
GMS difference of females (m = 0.0797, sd = 0.10072) in the
experimental group as can be seen in Table 3.
14
Table 3: GMS difference between Males and Females in the
Training Group
Gender in
N
Mean
Std. Dev.
Sig. (2Training
(Nm/kg)
(Nm/kg)
tailed)
Group
Males
7
0.0489
0.06312
p = 0.527
Females
5
0.0797
0.10072
Additional Findings
Dominant leg gluteus medius strength between the
experimental and control groups, non-dominant leg gluteus
medius strength between the experimental and control
groups, and the averages of the dominant leg and nondominant leg gluteus medius strength (GMS) between groups
were all analyzed for additional findings.
Dominant leg GMS comparing the experimental group to
the control group found that there was not a significant
difference between the means of the two groups (t = 1.786,
p = 0.098).
The mean GMS difference of the experimental
group (m = 0.0473, sd = 0.09376) was not significantly
different from the mean GMS difference of the control group
(m = -0.0029, sd = 0.02454) as can be seen in Table 4.
15
Table 4: Dominant leg GMS change between
the Training and Control Groups
N
Training
Group
Control
Mean
Std. Dev.
(Nm/kg)
(Nm/kg)
Sig. (2tailed)
12
0.0473
0.09376
p = 0.098
10
-0.0029
0.02454
Non-dominant leg GMS comparing the experimental group
to the control group found that there was a significant
difference between the means of the two groups (t = 2.649,
p = 0.015).
The mean GMS differences of the experimental
group (m = 0.0762, sd = 0.08523) was significantly
different from the mean of the control group (m = -0.0084,
sd = 0.05909) as can be seen in Table 5.
Table 5: Non-Dominant leg GMS change between the Training
and Control Groups
N
Mean
Std. Dev.
Sig. (2(Nm/kg)
(Nm/kg)
tailed)
Training
12
0.0762
0.08523
p = 0.015
Group
Control
10
-0.0084
0.05909
A paired-samples t-test was performed to determine if
there was a significant difference between gluteus medius
strength of the dominant and non-dominant legs in the
experimental group after six weeks of training.
There was
no significant difference (t = -1.143, p = 0.277) in the
mean GMS of the dominant leg compared to non-dominant leg
16
in the experimental group.
The mean of the dominant leg
GMS differences was 0.0473 (sd = 0.09376), and the mean of
the non-dominant leg GMS difference was 0.0762 (sd =
0.08523) as can be seen in Table 6.
Table 6: GMS difference between Dominant and
Non-Dominant Legs in the Training Group
N
Mean
Std. Dev.
Dominant
Non-Dominant
12
12
(Nm/kg)
(Nm/kg)
0.0473
0.0762
0.09376
0.08523
Sig. (2tailed)
p = 0.0277
A one-way ANOVA was performed comparing the average
GMS of the experimental group and the amount of days missed
(0,1,or 2).
No significant difference was found (F (2,9) =
2.507, p = 0.136).
The mean GMS difference for days missed
were 0 = 0.0968 ± 0.02496, 1 = 0.1032 ± 0.12078, and 2 =
0.0089 ± 0.02465 as can be seen in Table 7.
Table 7: Average GMS Difference Compared to Days Missed
Days
N
Mean
Std. Dev.
Sig. (2Missed
(Nm/kg)
(Nm/kg)
tailed)
0
4
0.0968
0.02496
p = 0.136
1
3
0.1032
0.12078
2
5
0.0089
0.05511
Total
12
0.07819
0.07819
17
DISCUSSION
The following is divided into three subsections:
Discussion of Results, Conclusion, and Recommendations.
Discussion of Results
The high rate of non-contact anterior cruciate
ligament injuries, specifically in females, has caused a
surge of research on preventative measures as well as NCACL
injury prevention programs.1,22-25
Injury epidemiology
research suggests that the hip and surrounding musculature
may play an important role in the poor biomechanics
associated with increased injury risk.1
The gluteal muscles
are the primary hip stabilizers, with the gluteus medius
being the primary hip abductors and lateral stabilizers.
The role of the gluteus medius and hip stabilizers in NCACL
injuries has lead to the inclusion of exercises in
prevention programs to improve strength and balance of
these muscles.9-14,22-25
The higher NCACL injury incidence
rate in females coupled with the decrease in gluteus medius
strength in females compared to males supports the theory
of the gluteus medius as a major component in the
18
prevention of NCACL injuries.4-7,9-14
An exhaustive search of
the literature did not yield any published studies that
have tested an ACL injury prevention program’s effect on
gluteus medius strength.
This study was performed to
provide data exploring potential strength changes in hip
musculature strength with the use of an ACL injury
prevention program.
The lack of research studying the change in hip
abductor strength following the implementation of an ACL
injury prevention program inspired this study incorporating
a six week implementation of the Trunk Neuromuscular
Training Program (TNT) and comparing the results of hip
abductor strength differences to a control group.
The
paucity of research in this area leads to little comparable
data for the first hypothesis that those in the training
group would significantly increase their gluteus medius
strength compared to those in the control group after the
TNT Program implementation.
Two studies, one by Chimera et
al and the other by Hewett et al, investigated hip abductor
musculature following a training protocol, however these
studies did not include strength measures.28,29
Chimera et
al noted a significant change in adductor to abductor
muscle co-activation during a vertical jump after the
implementation of a six week training protocol.28
19
Similarly, Hewett et al found a decrease in varus and
valgus movements following training and suggested the
results showed an increase in dynamic support of the hip
joint.29
protocol.
Each study utilized a plyometric based training
Plyometric training is the basis for the Trunk
Neuromuscular Training Program used in this study.
With
the observations of hip musculature change in these studies
we theorize that they support our findings of a significant
change, a 4.4% increase in average gluteus medius strength,
can be observed after the implementation of the Trunk
Neuromuscular Training Program after six weeks.
As previously stated, females suffer from a two to six
times higher incidence rate of NCACL injuries compared to
their male contemporaries.1,4-7 Several studies have also
shown that females differ significantly in hip abductor
strength and muscle activation patterns compared to males
of similar age.9-14
A large emphasis has been placed on
female NCACL injury research in previous years, which
explains why many programs that are currently available
employ language suggesting they are for female use.1,22-25
The Trunk Neuromuscular Training Program (TNT), designed by
Myer et al, is a prevention program that utilizes genderspecific language.24
This suggests, but does not confirm,
that it is intended by the authors for female use.
The
20
differences experienced by males and females during high
risk situations that may lead to a NCACL injury are well
documented.
The lack of research testing ACL injury
prevention programs extends into the realm of gender
differences experienced during the execution of a
prevention protocol.
To investigate our second hypothesis,
that females in the training group will increase their
gluteus medius strength significantly more compared to
males, we compared the gluteus medius strength differences
of the males in the experimental group to the females in
the experimental group.
The lack of a significant
difference suggests that the TNT program significantly and
equally strengthens the gluteus medius in both males and
females.
These results show an impartial change in GMS
despite noted anatomical, biomechanical, and hormonal
differences between males and females in relation to
anterior cruciate ligament injuries.2-4
These findings also
suggest that, despite females on average having a decrease
in GMS compared to males along with altered muscle
activation patterns according to Cowley et al, they do not
have strength increases that differentiate for the strength
gains seen in males.9-14
Further analysis of data used for the first hypothesis
was performed during additional findings.
These results
21
showed there was not a significant difference in dominant
leg GMS change in the experimental group, only 3.3%
increase, when compared to the control group, -0.4%.
This
is in contrast to the significant GMS difference
experienced by the non-dominant leg in the training group,
which was a 5.4% increase.
A comprehensive search of all
available research found only one study that examined hipabductor strength and leg dominance.
According to Jacobs
et al, the gluteus medius peak-torque is significantly
higher in the dominant leg compared to the non-dominant
leg.30
This may explain the lack of significant improvement
seen in the dominant leg gluteus medius when compared to
the non-dominant.
The majority of GMS was gained on the
non-dominant side which is, when compared to the results of
Jacobs et al, the weaker side.30 This could indicate that,
during this study, the progression of each phase in the TNT
program was dependent on the development of the nondominant leg gluteus medius strength.
While these findings
provide an intriguing theory, they remain in contrast to
the lack of significance between a comparison of GMS change
of the experimental group’s dominant and non-dominant legs.
A review of available literature indicates that many
studies focus on the dominant leg when collecting ACL
research.10,12,20,21
Using our results showing the non-
22
dominant leg gluteus medius receiving the majority of the
benefit, we can theorize that solely testing the dominant
leg could potentially skew the outcome of a research study.
Future research that would be of interest would use
parameters of a previous study that only tested the
dominant leg ACL and assess both legs.
The incorporation
of single leg as well as double leg exercises emphasizing
equal effort bilaterally are an important part of the Trunk
Neuromuscular Training program and has been cited by Myer
et al as an effective way of treating leg dominance.23,24
It
is for this reason that during the implementation of the
TNT program, the clinician needs to aware and attentive to
proper form so that the dominant leg is not overloaded,
potentially causing a neuromuscular pattern that could lead
to injury.
Statistics were also run to determine if the number of
training sessions missed altered the final dominant leg,
non-dominant leg, and average GMS scores of the subjects.
No published data was found to compare the number of
sessions missed in a protocol compared to reliability or
validity of the final results.
In an effective training
protocol, it is important to determine how many sessions
can be missed before strength gains begin to decrease as
compliance is usually not 100%.
For the purposes of this
23
study, the maximum number of sessions that the subjects
were able to miss was two.
Of the twelve subjects in the
experimental group four did not miss, three missed one day,
and five missed two days.
The results of the analysis
showed that there was not a significant difference between
the number of days missed and GMS in the experimental
group.
Despite the lack of significance, there was a
definite trend between those who missed zero or one day of
training compared to those who missed two days.
Those who
missed two days of training had a GMS score of .0943
Newtons, or about .924 kg of force, less than those who
missed either one or zero days of training. This may
suggest that future research should analyze similar
variables and exclude participants that miss multiple
sessions.
Conclusions
This study demonstrated that after a six week ACL
injury prevention program incorporating specific muscles
for the core and hip, there is a significant increase in
the average gluteus medius strength scores.
There was
significant difference in the average gluteus medius
strength scores between males and females in the
24
experimental group after the six weeks of training.
Additionally there was a lack of significance in the
difference of strength gains between the dominant leg
gluteus medius strength scores and the non-dominant leg
gluteus medius strength scores.
Finally, there was a lack
of significance in the post-test average, dominant and nondominant gluteus medius strength scores when compared to
the minimum and maximum amount of days missed, though there
was a definite drop-off trend noticed.
Our findings of higher strength gains in the nondominant leg as opposed to the dominant leg suggest that
weaker subjects may see a maximal benefit from the use of
this program seeing as the weaker side, non-dominant, saw a
larger increase in GMS.
The strength gains seen in males
and females imply that this program is significantly
effective for both genders as well as a variety of levels
of gluteus medius strength.
While gluteus medius strength
concerns only account for a small portion of the risk
factors associated with non-contact ACL injuries, the
widespread implementation of this program could potentially
decrease the number of injuries seen in relation to this
injury.
25
Recommendations
There is a lack of research investigating muscle
strength gains from ACL injury prevention programs.1
It is
extremely important to identify the most successful program
and the time frame in which the use of these programs can
provide the maximum amount of benefits between males and
females.
Our findings from this study, while not
staggering, show the benefits gained from the
implementation of a particular ACL injury prevention
program over a six week, 12 session period.
Larger numbers
studied may confirm the findings of our experiment.
The
next step would be to identify the minimal amount of time
needed to see meaningful benefits from the use of this
program.
Additionally, it would be interesting to study at
what point the benefits begin to plateau and the
introduction of a change in the program is needed.
Lastly,
testing of all muscles used in the prevention of noncontact ACL injuries, such as the quadriceps, hamstrings,
and abdominals, would further add legitimacy to the
prevention programs.
There was no significant difference noted between the
GMS scores of the males and females.
Muscle activation
patterns remain a significant theory in the cause of a
26
higher incidence rate of non-contact ACL injuries in
females.
For this reason it would behoove future
researchers to measure not only strength gains, but EMG
muscle firing patterns as well.
27
REFERENCES
1.
Hewett TE, Shultz SJ, Griffin LY, eds. Understanding
and Preventing Noncontact ACL injuries/American
Orthopaedic Society Sports medicine. 1st ed.
Champaign, IL: Human Kinetics; 2007.
2.
Shimokochi Y, Shultz S. Mechanisms of noncontact
anterior cruciate ligament injury. J Athl Training .
July 2008;43(4):396-408.
3.
Brindle T, Mattacola C, McCrory J. Electromyographic
changes in the gluteus medius during stair ascent and
descent in subjects with anterior knee pain. Knee Surg
Sport Tr A. July 2003;11(4):244-251.
4.
Uhorchak J, Scoville C, Williams G, Arciero R, St.
Pierre P, Taylor D. Riskfactors associated with noncontact injury of the anterior cruciate ligament: A
prospective four-year evaluation of 859 West Point
cadets. Am J Sport Med 2003; 31(6): 831-842.
5.
Arendt EA, Agel J, Dick R. Anterior cruciate ligament
injury patterns among collegiate men and women. J Athl
Training. 1999;34:86-92.
6.
Arendt E, Agel J, Dick R. Knee injury patterns among
men and women in collegiate basketball and soccer.
NCAA data and review of literature. J Athl Training.
June 1999;34(2):86-92.
7.
Arendt E, Dick R. Knee injury patterns among men and
women in collegiate basketball and soccer: NCAA data
and review of literature. Am J Sports Med.
1995;23:694-701.
8.
McKeon J, Hertel J. Sex differences and representative
values for 6 lower extremity alignment measures. J
Athl Training. May 2009;44(3):249-255.
9.
Russell K, Palmieri R, Zinder S, Ingersoll C. Sex
differences in valgus knee angle during a single-leg
drop jump. J Athl Training. April 2006;41(2):166-171
10.
Garrison J, Hart J, Palmieri R, Kerrigan D, Ingersoll
C. Comparison of knee-joint moments in male and female
28
college soccer players during a single-leg landing.
J Sport Rehabil. November 2005;14(4):332.
11.
Hughes G, Watkins J, Owen N. Gender differences in
lower limb frontal plane kinematics during landing.
ISBS. September 2008;7(3):333-341.
12.
Jacobs C, Uhl T, Mattacola C, Shapiro R, Rayens W. Hip
abductor function and lower extremity landing
kinematics: sex differences. J Athl Training. January
2007;42(1):76-83.
13.
Cowley H, Ford K, Myer G, Kernozek T, Hewett T.
Differences in neuromuscular strategies between
landing and cutting tasks in female basketball and
soccer athletes. J Athl Training. January
2006;41(1):67-73.
14.
Ford K, Myer G, Toms H, Hewett T. Gender differences
in the kinematics of unanticipated cutting in young
athletes. Med Sci Sport Exer. August 2005;37:129-9.
15.
Hewett T, Ford K, Myer G, Wanstrath K, Scheper M.
Gender differences in hip adduction motion and torque
during a single-leg agility maneuver. J Orthopaed Res.
March 2006;24:416-421.
16.
Liu X, Tingle T, Lintner D, Lowe W, Zhai Q, Luo Z.
Difference in collagen gene expression in male and
female anterior cruciate ligament injured athletes.
Biol Sport. 2009;26(3):255-261.
17.
Eiling E, Bryant A, Petersen W, Murphy A, Hohmann E.
Effects of menstrual-cycle hormone fluctuations on
musculotendinous stiffness and knee joint laxity. Knee
Surg Sport Tr A. February 2007;15(2):126-132.
18.
Hertel J, Williams N, Olmsted-Kramer L, Leidy H,
Putukian M. Neuromuscular performance and knee laxity
do not change across the menstrual cycle in female
athletes. Knee Surg Sport Tr A. September
2006;14(9):817-822.
19.
Hart J, Garrison J, Kerrigan D, Palmieri-Smith R,
Ingersoll C. Gender Differences in Gluteus Medius
Muscle Activity Exist in Soccer Players Performing a
29
Forward Jump. Res Sports med. April 2007;15(2):147155.
20.
Hanson A, Padua D, Blackburn J, Prentice W, Hirth C.
Muscle activation during side-step cutting maneuvers
in male and female soccer athletes. J Athl Training.
March 2008;43(2):133-143.
21.
Brindle T, Mattacola C, McCrory J. Electromyographic
changes in the gluteus medius during stair ascent and
descent in subjects with anterior knee pain. Knee Surg
Sport Tr A. July 2003;11(4):244-251.
22.
Filipa A, Byrnes R, Paterno MV, Myer GD, Hewett TE.
Neuromuscular training improves performance on the
star excursion balance test in young female athletes.
J Orthop Sport Phys. September 2010;40(9):551-8.
23.
Myer G, Chu D, Brent J, Hewett T. Trunk and hip
control neuromuscular training for the prevention of
knee joint injury. Clin Sport Med. 2008;27(3):425448.
24.
Myer G, Ford K, Hewett T. Rationale and clinical
techniques for anterior cruciate ligament injury
prevention among female athletes. J Athl Training.
October 2004;39(4):352-364.
25.
Myer G, Ford K, Brent J, Hewett T. Differential
neuromuscular training effects on ACL injury risk
factors in “high-risk” versus “low-risk” athletes. BMC
Musculoskelet Disord. May 2007;39(8):1-7.
26.
Hollman JH, Kolbeck KE, Hitchcock JL, Koverman JW,
Krause DA. Correlations between hip strength and
static foot and knee posture. J Sport Rehabil.
2006;15:12-23.
27.
The Lafayette Manual Muscle Test System user’s manual.
Lafayette, IN: Lafayette Instrument. 2003.
28.
Chimera NJ,
training on
performance
2004;39(1):
Swanik KA, et al. Effects of plyometric
muscle-activation strategies and
in female athletes. J Athl Training.
24-31.
30
29.
Hewett TE, Stroupe AL, Nance TA, Noyes FR. Plyometric
training in female athletes. Decreased impact forces
and increased hamstring torques. Am J Sports Med.
1996; 24(6): 765-773.
30.
Jacobs C, Uhl TL, Seeley M, Sterling W, Goodrich L.
Strength and fatigability of the dominant and
nondominant hip abductors. J Athl Training. July
2005; 40(3): 203-206.
31
APPENDICES
32
APPENDIX A
Review of Literature
33
REVIEW OF LITERATURE
The purpose of this literature review is to discuss
the gluteus medius and its relationship to non-contact
anterior cruciate ligament (NCACL) injuries and ACL injury
prevention programs. Anterior cruciate ligament injuries
are one of the most prevalent injuries in athletics. It has
been suggested that 75,000 to 250,000 ACL tears occur in
the United States each year.1 Unfortunately, for female
athletes, they suffer a four to six time higher incidence
rate for non-contact ACL injuries compared to male athletes
of a similar age.1
While current research has brought us
closer to understanding this discrepancy, there remain
uncertainties to this complicated issue.
Several factors
for the increase in injury among females have been
suggested.
These factors include anatomical, hormonal,
biomechanical, and neuromuscular differences between
genders.1,2
Regardless of gender, it is important to
implement injury prevention programs that focus on reducing
the occurrence of anterior cruciate ligament injuries.
The gluteus medius plays a key role in the prevention
of patellofemoral injuries.3 The strengthening of this
muscle should be included in any preventative ACL injury
program.
Not all prevention programs include the same
34
components, so it is extremely important to understand the
components and the effectiveness of these programs.
This
literature review will outline the importance of the
gluteus medius in ACL injury prevention by discussing what
a noncontact ACL injury is, the anatomy involved including
the functional anatomy, the role of the gluteus medius, and
specific gender differences as well as mechanical
alterations and current ACL prevention programs and their
components.
Noncontact ACL Injuries
For an ACL injury to be considered noncontact, there
needs to be an absence of outside contact with the knee
during the time of injury.
While the exact etiology of
noncontact anterior cruciate ligament injuries remains
unknown,1 recent research has aided in our understanding of
risk factors.
A study by Griffin et al defined
environment, anatomy, hormonal, and biomechanics as the
four typical risk factors for ACL injuries.4 These factors
will be discussed in later sections in more detail.
Situations that can create a force necessary for a
noncontact ACL injury include, but are not limited to,
landing from a jump, sudden changes in direction, and
35
deceleration.1 Most noncontact anterior cruciate ligament
injuries tend to happen in the closed kinetic chain. When
the body is in direct contact with the physical
environment, it can create a model situation for injury.
For example, during a drop jump landing, an increase in
knee valgus force coupled with internal rotation of the
femur creates a common mechanism of injury.1 The increase
in internal rotation of the femur can be due to a weakness
in hip external rotators, including the gluteus medius.
Muscular weakness is also a major contributor to
noncontact ACL injury. A lack of co-contraction of the
hamstrings during quadriceps contraction can create the
shear forces necessary to cause an anterior cruciate
ligament injury when the knee is at or near full extension.
Understanding of the definition of noncontact ACL injuries
is important when trying to determine the incidence of
these injuries in sports.
Incidence
The incidence of noncontact anterior cruciate ligament
injuries has been estimated at approximately 70% of all ACL
injuries.1,4
Prevalence and incidence are two separate
concepts that are, unfortunately, commonly misused and
misunderstood.
Incidence is the rate in which something
36
occurs within a population.
Incidence as it pertains to
ACL injury research is done in a prospective manner
studying the number of injuries sustained in a group of
subjects during a predetermined amount of time.
It is
difficult, if not impossible, to determine the number of
anterior cruciate ligament injuries within the general
population.
Even with the National Ambulatory Care
Surveys, all cruciate ligament injuries are reported under
the same ICD code, creating mixed numbers.
Even if it were
possible to differentiate between the injuries in this
situation, the survey covers total visits for ACL injuries,
which could be an indeterminable number per patient.1
With
these limitations aside, incidence rates have been
determined in smaller populations.
There have been many
studies that focus on anterior cruciate ligament injury
within specific athletic populations.
A study done by Uhorcak et. al. analyzed 859 West
Point Cadets over four years to better understand the
incidence and risk factors that are present in an athletic
population.5
While military men and woman are not
considered athletes, their training and conditioning are
certainly athletic in nature, therefore allowing for
comparisons.
All 859 cadets were assessed by physical
examination, strength assessment, and exposure data.
Of
37
the 859 cadets there were 29 anterior cruciate ligament
injuries over the four year study.
were considered noncontact.
Twenty four of these
This is an incidence rate of
approximately 3.4% in the general population and an 82.7%
noncontact injury rate, which is significantly higher than
the previously noted 70%.
The benefit of this study is
that it incorporates males and females as well as clearly
defining noncontact ACL injuries.
The differentiation of
male and female subjects is important because it shows the
large discrepancy between the genders.
The incidence rate
for females was found to be 6.6% while it was only 2.1% in
males.
The authors cite specific anatomical and
physiological reasons that are to be discussed later in
this review.
The National Collegiate Athletic Association Injury
Surveillance System (ISS) was developed in 1982 to provide
the most up to date and reliable data on injury trends.
This has been an invaluable tool for researchers trying to
identify injury discrepancies between sports, gender, and
collegiate division.
A study done by Agel et al6 used the
ISS to follow noncontact ACL injuries between males and
females participating in basketball and soccer. This study
was built upon previous results,7,8 giving an extensive look
into ACL injury patterns.
When the researchers compared
38
noncontact ACL injuries between genders, the results were
mostly similar to previous studies.
Male basketball
players suffered a 70.1% rate of noncontact ACL injuries
compared to contact while female basketball players
suffered a 75.7% rate.
Males suffered 37 contact and 78
noncontact injuries, while females suffered 100 contact and
305 noncontact ACL injuries.
Though this was not
considered a significant difference from previous results,
the results from soccer showed a note worthy change.
Male
soccer players suffered a 49.6% rate of noncontact anterior
cruciate ligament injuries while the rate for females was
58.3%.
The 49.6% rate for males was considered a
significant decrease, which causes one to wonder as to the
reason for the change.
Further results from the study
showed that regardless of the sport, females had a much
higher incidence rate of anterior cruciate ligament injury.
While this information is extremely important in the
identification of the injury discrepancy, it does not mean
that ACL injuries in males should be ignored, especially
since there are more males experiencing NCACL injuries per
year than females.
39
Anatomy
It is extremely important to understand the anatomy
involved in anterior cruciate ligament injuries.
In order
to understand the possible etiologies of noncontact ACL
injuries, one must understand how stability is maintained
within the knee joint.
There are two joints within the
complex of the knee, the patellofemoral and tibiofemoral.
The patellofemoral joint is the articulation of the patella
and the femur, while the tibiofemoral joint is articulation
of the femur on the tibial plateau.
Additionally, there are two types of stabilizers in
the knee; passive and dynamic.
Passive stabilization is
provided by the joint capsule, the menisci, the anterior
cruciate ligament, the posterior cruciate ligament (PCL),
the lateral collateral ligament (LCL) and the medial
collateral ligament (MCL).
Dynamic stabilization is
provided by the muscles that cross the knee joint, which
are the quadriceps muscles and the hamstring group.9
Reference to how important the ACL is can be heard
nearly every time a star athlete sustains a knee injury,
but often times the general public lacks the understanding
of why it is so important.
The main functions of each of
the cruciate ligaments (ACL and PCL) are exact opposites.
40
The ACL attempts to impede anterior tibial translation on
the femur and the PCL attempts to stop a posterior shear
force of the tibia on the femur.
While this may seem
backwards, the ligaments receive their names from their
origins.
The ACL originates at the anterior intercondylar
area of the tibial plateau and inserts to the
posteriomedial part of the lateral femoral plateau.
Conversely, the PCL originates in the posterior aspect of
the intercondylar notch and inserts at the anterior
inferior lateral aspect of the medial femoral plateau.9
Anatomy Involved in ACL Injury
According to Griffin et al, there has not yet been a
reliable measure of any single anatomical variable that
increases the risk of anterior cruciate ligament injury.10
This does not, however, discount the fact that several
anatomical factors have been suggested as risk factors for
ACL injury.
These factors include femoral intercondylar
notch width, pelvic angle, quadriceps angle, and subtalar
pronation.1
Suggestions of intercondylar notch width’s
relationship to ACL injury are not a recent development,
and yet there is little empirical data that can give a
definitive answer.
Also, recent conflicting MRI studies
41
have increased the uncertainty.11,12
The exact correlation
between a decreased intercondylar notch width and ACL
injury has not been specified.
However, further findings
in the study done by Uhorchak et al.5 suggested that the
increase of ACL injury in those with a smaller
intercondylar notch width could be due to an abnormal
loading of the ACL as well as a smaller ACL, which would
lead to a decrease in the ultimate failure point of the
ligament.
Unlike intercondylar notch width, there is little
controversy surrounding the hypothesis of pelvic angle’s
effects on ACL injury.
It has been suggested that an
increase in anterior pelvic tilt can create a medial
collapse of the lower extremity, causing internal rotation
of the femur leading to genu valgus at the knee.
It has
also been noted that anterior pelvic tilt can create other
structural abnormalities such as genu recurvatum and
subtalar pronation.13
Dynamic stability is also compromised
due to a stretch weakness of the hamstrings.
The quadriceps angle, also known as the “Q” angle, is
a measurement formed by the alignment of the center of the
patella to the anterior superior iliac spine and the center
of patella to the tibial tuberosity.
It is well documented
that a Q angle greater than 20 degrees can lead to a
42
patellofemoral pathology.14 An increased quadriceps angle
can also lead to an increase in knee valgus and torsion
within the knee.1
Subtalar pronation is often overlooked in patients
with an ACL injury.
Pes planus is typically the cause of
subtalar pronation.
The excessive pronation that is
occurring at the joint creates an internal rotation of the
femur, leading to internal rotation at the knee.15
This
internal rotation at the knee places a stress on the ACL
and may contribute to a higher risk for injury.
This is a
condition that can easily be exaggerated by other
biomechanical issues, such as an internal rotation of the
femur, causing a larger medial collapse.
It is important to note that anterior cruciate
ligament injuries are typically a result of several
factors.
Though some of the mentioned studies focus on a
single reason, it does not indicate that other factors were
not present.
There are other factors that have been
suggested, but have little to no supporting evidence.
These factors include femur to tibia length, anteversion of
the hip, tibiofemoral angle and genu recurvatum.1
43
Role of Gluteus Medius
The primary function of the gluteus medius is to
abduct the hip and internally rotate the thigh.
It takes
its origin from the iliac crest and inserts on the greater
trochanter.16,17
The gluteus medius is also a pelvic
stabilizer, which is extremely important in preventing a
medial collapse and maintaining proper kinematics of the
lower extremity.18
A medial collapse is characterized by an
internal rotation of the femur, knee valgus, and subtalar
In a study performed by Brindle et al.3 gluteus
pronation.
medius weakness was found to be related to anterior knee
pain in subjects performing ascent and descent of stairs.
With this in mind, it only seems right to implement a
comprehensive strength training prevention program that
effectively targets the gluteus medius and surrounding
musculature.
Differences between Gender
Gender differences have been suggested in several
studies as a reason for the greater incidence of NCACL
injuries in females.19-32
This leads to the discussion of
several areas where key differences have been studied;
anatomical,19 knee valgus angle,20-25 femoral internal
44
rotation,26 hormonal differences,27-30 and muscle activation
patterns.31,32
Recent research has identified four typical anatomical
differences between males and females that may lead to
NCACL injuries.
Medina et al collected measurements from
118 males and females ranging from active adults to elite
athletes.19
Their findings showed that women demonstrate
larger quardriceps angles, more genu recurvatum, greater
anterior pelvic tilt and larger femoral anteversion when
compared to males.
The researchers suggest that the
structural differences can lead to biomechanical
alterations.19
Single leg landings are a functional test that
multiple studies use to test knee valgus angles.
Many
sports require athletes to jump, and this sudden
deceleration is a typical mechanism for anterior cruciate
ligament rupture.1
Studies done by Russell et al.,20
Garrison et al.,21 Hughes et al.,22 and Jacobs et al.23
implemented the use of a drop jump to measure valgus angles
in the knee between the genders.
Each study found that
females exhibited a greater valgus angle during their
landings when compared to males.
Two of the studies also
tested for differences between the genders’ hip abduction
upon landing.20,22
One study did not find a difference in
45
muscle activation strategy between males and females,20
while the other’s findings suggested that females
demonstrate a lower activation rate of hip abduction.22
Differences are not only seen between genders in the
case of knee valgus, but also between females participating
in different sports.
In a study done by Cowley et al24
between female basketball and soccer players it was found
that females typically demonstrated greater knee valgus
angles during sport specific tasks, such as jumping and
landing in basketball and cutting in soccer.
The results
of this study also discovered greater knee valgus moments
during cutting tasks compared to landing tasks among
females.
This supports the incorporation of sport specific
movements into NCACL injury prevention programs to
strengthen the appropriate musculature and possibly
decrease knee valgus angles.
Gender differences have been noted as early as twelve
years of age by Ford et al25. In their study, in which 54
male and 72 female athletes of adolescent age performing a
cutting maneuver, it was found that the females suffered
from not only greater knee valgus angles during the landing
and stance phases when compared to males, but also from a
higher maximum ankle eversion during the landing phase and
46
decreased inversion during the stance phase.
This suggests
that ACL injuries may be influenced by ankle kinematics.
Many studies tend to focus on knee valgus measurements
instead of potential causes for an increase in hip
adduction.
In a study by Hewett et al26 hip adduction
angles were measured in male and female athletes performing
a single leg, bidirectional deceleration maneuver.
Results
of this study showed that females suffer from a larger
angle of hip adduction during all phases of the maneuver.
An increase in hip adduction motion can predispose an
athlete to a functional medial collapse, creating a perfect
environment for NCACL injury.26
Another area of difference between genders involves
changes at the molecular and hormonal levels.
A difference
in collagen gene expressions between genders is a
relatively recent area of study in consideration of
anterior cruciate ligament injuries.27
There are primarily
two types of collagen in the ACL; type I collagen and type
III collagen.
Type I collagen makes up about 90% of the
ACL while type III makes up approximately 10%.25
Liu et al
harvested the ACLs of 17 male and 17 female athletes who
required ACL reconstruction and tested them using reverse
transcript-polymerase chain reaction to determine if a
difference in fibroblast collagen gene expression existed.
47
Their findings showed a significantly different lower
relative expression of collagen I in the females.
The
question remains as to why this is the case, but the
researchers do theorize that hormonal differences may be
the cause.27
A 2006 study by Eiling et al28 focused on the effects
of the menstrual cycle on musculotendinous stiffness as
well as knee laxity.
The tests were performed during each
phase of the menstrual cycle using a knee arthrometer.
The
measurements that were produced showed, on average, a 4.2%
decrease in musculotendinous stiffness during the ovulatory
phase.27
The decrease in musculotendinous stiffness can
lead to a reliance on noncontractile tissue to support a
joint.
In this case that would mean more forces acting on
the ACL in female athletes than male athletes.
This
evidence was supported in 2007 by a survey study that
viewed previous ACL injuries of females and the stage of
their menstrual cycle at the time of injury.
72% of the
subjects who had suffered a noncontact ACL injury did so
during the ovulatory phase.28
Suggestions of hormonal relations to non contact ACL
injuries in females are not, however, fully supported.
Both studies previously mentioned suffer from a limited
sample size.
While they both present an interesting look
48
into the possibilities of the subject, neither has been
validated and are, in fact, currently being challenged as
incorrect through a research study underway at Pennsylvania
State University using similar methods.29
A difference in muscle activation patterns between
genders has been suggested as a cause for the higher
incidence of NCACL injuries in females.24,30,31
A delayed or
limited activation of certain muscles during the landing
phase of a jump, like the gluteus medius, may lead to NCACL
injuries.
Similarly, if there is a delay or an over
compensation in muscle activation patterns during cutting
tasks there is a possibility for injury.
A study by Hart et al30 examined eight male and eight
female soccer players performing a single leg landing.
The
researchers collected surface electromyography data from
the gluteus medius, vastus lateralis, lateral hamstring,
and medial gastrocnemius during the jumps of each
participant.
Their results showed that the males had
significantly higher gluteus medius activity during the
landing when compared to the females.
Hanson et al32 recorded surface electromyographic
activity for the rectus femoris, vastus lateralis, medial
and lateral hamstrings, gluteus medius and gluteus maximus
during a running-approach side-step cut and a box-jump
49
side-step cut in twenty males and twenty females.
The
participants used in the study were NCAA division I
athletes.
Results from this study demonstrated that
females suffer from larger quadriceps activation as well as
a larger quadriceps to hamstring coactivation ratio.
The
greater activation of the quadriceps without the hamstrings
counter balancing them creates an anterior shear force
within the knee, placing stress directly on the ACL. These
findings are also significant in that they confirm that the
quadriceps to hamstrings coactivation ratio exists in
advanced athletes as well as recreational athletes.31
Mechanical Alterations
Structural alterations are not solely responsible for
the occurrence of ACL injuries.
Dynamic factors such as
fatigue can create a harmful situation for the athlete.
These mechanical alterations can lead to a loss of dynamic
stability, leaving the anterior cruciate ligament prone to
injury.
The relationship of muscle fatigue and ACL injury
has been previously suggested.32,33
Chappell et al.32 found
that knee kinetics are significantly affected when muscle
fatigue is introduced to three jump stop tasks.
The
results showed an increase in anterior tibial translation,
50
which can place an undesirable stress on the ACL, possibly
causing injury.
In a related study by Melnyk and
Gollhofer,33 fatigue in the hamstrings was found to cause an
increase in anterior tibial translation as well.
The
decrease in latency response of the hamstrings
significantly affected the muscles ability to stabilize the
knee joint.
Fatigue of hip abductors also presents a
Carcia et al34 outlined a study
problem to the athlete.
that created bilateral fatigue in the hip abductors of
their participants and then observed changes in their
landing characteristics during a drop jump.
The fatigue of
hip abductors was found to significantly increase knee
valgus, possibly leading to injury in the ACL.
Prevention Programs
After reading through the research on ACL injuries,
there is a quick realization that preventative measures
need to be taken to combat these injuries.
Different
techniques have been used and implemented to decrease the
incidences of ACL injury.
Recently there have been
significant gains in NCACL injury prevention programs
focusing on neuromuscular training programs that have been
shown to reduce the incidence of NCACL injuries.36-37
51
Components
Neuromuscular training programs focus on a decreased
risk of injury.
While not all programs are the same,
typically the more common components of successful programs
include technique training and plyometric training.
A
relatively new suggestion involving the implementation of
core exercises to increase stability and proprioception is
theorized to have an effect on lower extremity
kinematics.36-38
Previous Results
Seeing the need for prevention programs, many studies
have tested the effects of certain exercises on musculature
as well as prevention programs as a whole.
It is important
to identify which muscles need to be strengthened.
Many
studies identify gluteus medius weakness as a
predisposition to injury.3-5,16-18,22,25,30,34
Though the gluteus
medius is an important muscle, it is certainly not the only
muscle of interest concerning ACL injury prevention.
The
sheer amount of literature on the subject proves that there
is no single answer to this complicated problem.
In
order to understand where ACL prevention programs are
52
going, it is necessary to understand the related
literature.
McCurdy et al tested the electromyography activity in
specific muscle groups of the hip and knee during a single
leg squat as well as a two legged squat.40
Eleven female
athletes were tested during three repetitions at 85% of
each athlete’s one repetition maximum.
The results from
the study show that single leg squats produce a higher mean
peak activity in the gluteus medius and hamstrings while a
two legged squat’s activity levels are higher in the
quadriceps.
These results suggest that when training to
target the gluteus medius muscle, single leg squats are
more effective than two legged squats.40
The study’s focus
on females prevents a complete translation in similarity to
males, but it does allow for some speculation.
In a study done by Boudreau et al, muscle activation
patterns of the rectus femoris, gluteus maximus, and
gluteus medius were measured in 44 healthy individuals
while performing three trials of lunges, single leg squats,
and step up and overs.
The results found that lunges were
the best choice of the three exercises for gluteus medius
activation.41
Although the study was performed using an
equal number of men and women, the study mentions no
differences between the genders in the levels of muscle
53
activation for each exercise.
These results clearly show
that lunges can be potentially one of the best exercises
when attempting to strengthen hip abductors.
Further studies outline marked improvements in
neuromuscular training’s effects on noncontact ACL injury
prevention.42-45
It is interesting though, that there has
been an abundance of research on the different effects of
NCACL injury prevention training, but there has not yet
been a clear decrease in the occurrence of this injury.6,46
Use of Prevention Programs
Before a prevention program is fully implemented,
Hewett et al suggests that the participant is evaluated
through a series of jump tasks to identify ligament
dominance, quadriceps dominance, and leg dominance.47
These
are three neuromuscular risk factors that are easily
identifiable and can be corrected during the execution of
the program.
With ligament dominance there is an imbalance
of neuromuscular control, leading to a reliance on the
ligament for the majority of support.48
This is typically
characterized by a lack of control of knee valgus during
jumping and cutting and should be identified by watching
the subject perform a maximal vertical jump.46
Quadriceps
dominance is presented as an unproportionate increase in
54
the quadriceps to hamstring ratio, with the quadriceps
muscle overpowering the hamstrings.49
This creates a
shearing force within the knee, placing stress on the ACL.
Dominance of the quadriceps can be determined easily
through the use of leg curl and leg extension machines.
If
the subject has a hamstring to quadriceps ratio of less
than 55% they may be considered to suffer from quadriceps
dominance.47
Leg dominance is defined as a lack of
strength, coordination and balance before the lower limbs
by Myer et al.47
There are several different ways to test
for leg dominance.
The first method is to measure strength
and determine if one limb can exceed the other by 20% or
more.
The second method consists of a balance test to
observe postural sway.
The final measurement of leg
dominance is the use of a four quadrant exercise.
In this
exercise the subject stands on a single limb and hops
across and diagonal into the corresponding quadrants,
holding each position for three seconds.
The subject’s
ability to maintain stability is the sole measure for this
exercise.47
It is extremely important to attempt to
eliminate the risk of injury during the implementation of
prevention programs because subjects may sometimes be
placed in positions their bodies are unfamiliar with.
55
Summary
The current estimations of 75,000 to 250,000 ACL
injuries a year create a need for the implementation of
NCACL prevention programs to reduce the incidence of this
injury.
Of these 75,000 to 250,000 ACL injuries, it has
been suggested that 70% of them are considered noncontact.1
The gluteus medius muscle has been identified as an
important component of noncontact ACL injuries.
It is
considered important due to its primary function, which is
to abduct the hip and internally rotate the thigh.16,17
The
strengthening of the gluteus medius muscle may help in the
prevention of a functional medial collapse, which could
lead to damaging the ACL.3
There is currently a large
amount of research focusing on female athletes and a higher
incidence of injury compared to males.
Regardless of which
gender is more at risk, it is important to identify
strength training programs that can aid in the reduction of
ACL injuries.
Current programs in use need to be tested to
observe their effectiveness in related musculature as well
as their value between genders.
56
APPENDIX B
The Problem
57
Statement of the Problem
The purpose of the study is to examine the effect of
an ACL injury prevention program on gluteus medius strength
between males and females.
It is important to examine this
relationship because current research shows a direct
relationship between the strength of the gluteus medius and
ACL injuries.
Strengthening the gluteus medius may aid in
the reduction of stressors in the lower extremity due to
joint malalignment.
It is also important to determine if
males and females benefit similarly to determine if there
is a need for more or less gender specific ACL injury
prevention programs.
The knowledge gained from this study
may be beneficial to those looking to prevent ACL injuries.
We do not know if there will be significant gains in
gluteus medius strength through the use of the Trunk
Neuromuscular Training Program, and we also do not know if
there will be a difference in the benefits gained between
the genders.
Definition of Terms
The following definitions of terms will be defined for
this study:
1)
ACL Prevention Program – A program that is designed to
prevent an injury of the anterior cruciate ligament
58
through the use of neuromuscular and proprioceptive
training techniques.
2)
Physically active college aged students – Study
participant that engages in physical activity for at
least 30 minutes three times a week and are aged
between 18 and 26.
3)
Lafayette Manual Muscle Test System (MMTS) – a device
used to objectively measure muscle strength.
Basic Assumptions
The following are basic assumptions of this study:
1)
All subjects will follow the exercise protocol they
have been assigned.
2)
The subjects will put forth a maximal effort during
their exercise sessions and during strength testing.
3)
The subjects will be honest in their completion of the
demographic forms.
4)
All testing instruments are valid and reliable tools
that are used for their intended purpose.
5)
Subjects for the study are volunteers who were not
coerced in any way to participate.
Limitations of the Study
The following are possible limitations of the study:
59
1)
The number of participants involved in this study may
not be large enough for significant results.
2)
Findings are limited to active, college-aged
recreational student athletes.
3)
The six week time limit for the implementation of the
exercises programs may not be long enough for
significant results to be achieved.
Significance of the Study
Anterior cruciate ligament injuries are among the most
devastating injuries that can be sustained by athletes.
Currently, it is estimated that between 75,000 and 250,000
ACL injuries occur each year.
The gluteus medius muscle
provides an important role in preventing lower extremity
injuries through stabilization of the pelvis.
The
stabilization of the pelvis contributes to preventing a
valgus collapse of the knee, which is characterized by
internal rotation of the femur, knee valgus, and ankle
pronation.
There are several ACL injury prevention
programs that are currently available to the public.
This
study uses an ACL injury prevention program to test it’s
effects on the gluteus medius muscle between males and
females.
Current research indicates a higher incidence of
ACL injuries in the female population when compared to
60
males.
For this reason, many prevention programs have been
tailored to the female population.
It is crucial to
determine if males and females both benefit similarly from
currently available ACL injury prevention programs.
The
information gained from this study may provide future
researchers with an understanding of what programs provide
the best results.
The information gained from this study
may also show that there may be a need for more or less
gender specific ACL injury prevention programs.
61
APPENDIX C
Additional Methods
62
APPENDIX C1
Informed Consent Form
63
Informed Consent Form
1. Jordan Blair, who is a Graduate Athletic Training Student at California University of
Pennsylvania, has requested my participation in a research study at California University
of Pennsylvania. The title of the research is The Effect of an ACL Injury Prevention
Program on Gluteus Medius strength between Genders
2. I have been informed that the purpose of this study is to examine the effect of an ACL
injury prevention program on gluteus medius strength between males and females. I
understand that I must be 18 years of age or older to participate. I understand that I have
been asked to participate along with 31 other individuals because I am physically active,
as defined as participating in moderate to intense exercise at least 3 times a week
3. I have been invited to participate in this research project. My participation is voluntary
and I can choose to discontinue my participation at any time without penalty or loss of
benefits. My participation will involve pre and post testing to occur before and after the
implementation of either the Trunk Neuromuscular Training (TNT) program over six
weeks or no exercise assignment over six weeks. I acknowledge that the TNT program
will involve an exercise session to meet two times a week taking approximately 25
minutes to complete including the exercises associated with the program as well as a
warm up. I also acknowledge that these exercises will be demonstrated to me on the first
day of my exercise program.
4. I understand there are foreseeable risks or discomforts to me if I agree to participate in
the study. With participation in a research program such as this there is always the
potential for unforeseeable risks as well. I understand that the risks I may be exposed to
include, but are not limited to, soreness associated with exercise as well as injuries that
may be sustained during normal bouts of physical activity that involve the lower
extremity.
5. I understand that, in case of injury, I can expect to receive treatment or care in Hamer
Hall’s Athletic Training Facility. This treatment will be provided by the researcher,
Jordan Blair, under the supervision of the CalU athletic training faculty, all of which can
administer emergency care. Additional services needed for prolonged care will be
referred to the attending staff at the Downey Garofola Health Services located on
campus.
6. There are no feasible alternative procedures available for this study.
7. I understand that the possible benefits of my participation in the research is to
contribute to existing research and may aid in the enhancement of ACL injury prevention
programs.
64
8. I understand that the results of the research study may be published but my name or
identity will not be revealed. Only aggregate data will be reported. In order to maintain
confidentially of my records, Jordan Blair will maintain all documents in a secure
location on campus and password protect all electronic files so that only the student
researcher and research advisor can access the data. Each subject will be given a specific
subject number to represent his or her name so as to protect the anonymity of each
subject.
9. I have been informed that I will not be compensated for my participation.
10. I have been informed that any questions I have concerning the research study or my
participation in it, before or after my consent, will be answered by:
Jordan Blair, ATC
STUDENT/PRIMARY RESEARCHER
Bla5790@calu.edu
412-477-5657
Shelly DiCesaro, PhD, ATC, CSCS
RESEARCH ADVISOR
Dicesaro@calu.edu
724-938-5831
11. I understand that written responses may be used in quotations for publication but my
identity will remain anonymous.
12. I have read the above information and am electing to participate in this study. The
nature, demands, risks, and benefits of the project have been explained to me. I
knowingly assume the risks involved, and understand that I may withdraw my consent
and discontinue participation at any time without penalty or loss of benefit to myself. In
signing this consent form, I am not waiving any legal claims, rights, or remedies. A copy
of this consent form will be given to me upon request.
13. This study has been approved by the California University of Pennsylvania
Institutional Review Board.
14. The IRB approval dates for this project are from: 02/24/11 to 02/23/12.
Subject's signature:___________________________________
Date:____________________
Witness signature:___________________________________
Date:____________________
65
APPENDIX C2
Institutional Review Board –
California University of Pennsylvania
66
Proposal Number
Date Received
PROTOCOL for Research
Involving Human Subjects
Institutional Review Board (IRB) approval is required before
beginning any research and/or data collection involving human subjects
(Reference IRB Policies and Procedures for clarification)
Project Title The Effect an ACL Injury Prevention Program on Gluteus Medius Strength Between Genders
Researcher/Project Director
Jordan Blair
Phone # 412-477-5657
E-mail Address BLA5790@calu.edu
Faculty Sponsor (if required) Dr. Shelly Dicesaro
Department Health Science
Project Dates January 2011 to June 2011
Sponsoring Agent (if applicable)
Project to be Conducted at California University of Pennsylvania
Project Purpose:
Thesis
Research
Class Project
Keep a copy of this form for your records.
Other
67
Please attach a typed, detailed summary of your project AND complete items 2
through 6.
1. Provide an overview of your project-proposal describing what you plan to do and how you
will go about doing it. Include any hypothesis(ses)or research questions that might be
involved and explain how the information you gather will be analyzed. For a complete list of
what should be included in your summary, please refer to Appendix B of the IRB Policies and
Procedures Manual.
The purpose of this study is to examine the effects of an ACL injury prevention program on
gluteus medius strength between males and females. Physically active students, ages 18 to
26, from California University of Pennsylvania are expected to participate in this study
(N~32). Subjects that are currently suffering or recovering from a lower extremity injury
sustain within the past 6 months will not be included in this study. The subjects who sign the
informed consent will be randomly assigned into two separate groups (N~16) consisting of
equal numbers of males (N~8) and females (N~8). One group will be the experimental group
that will be given the pre test, prevention program, and post-test, while the other group will
be the control that will only receive the pre-test and post-test. Gluteus medius strength will
be measured before and after the implementation of the ACL injury prevention program,
using the hand held Lafayette Manual Muscle Test System (MMTS), which is a small handheld device that is placed over top of the muscle during a contraction to provide an objective
measure of muscle strength. Testing will be done on both legs. For the muscle test, the
subjects will lay on the opposite side that is being tested and the MMTS will be placed over
the gluteus medius, which is located on the side of their hip. The subjects will then gradually
push as hard as they can against the MMTS which will be in the researcher’s hand. The pretest measurement will provide a baseline from which to observe the effect of the program on
gluteus medius compared to the control group. Demonstrations of each exercise will be done
the first day of subject’s participation to familiarize the subjects with the exercises. The
researcher will also be available during the scheduled time for the subjects exercise sessions.
Exercise sessions will be formulated based on the schedules of the subjects as well as the
researcher. A log book will be kept to ensure attendance of the subjects. If any subject
misses more than two scheduled exercises sessions or two sessions in a row they will be
excluded from the study. Pictures and descriptions of all exercises from the program are
attached. The following hypotheses will be investigated during this study; the trunk
neuromuscular training program will significantly increase gluteus medius strength when
compared to the control group. All data that is collected will be analyzed by SPSS for
windows version 17.0 at an alpha level of .05 using a two way ANOVA.
2. Section 46.11 of the Federal Regulations state that research proposals involving human
subjects must satisfy certain requirements before the IRB can grant approval. You should
describe in detail how the following requirements will be satisfied. Be sure to address each
area separately.
a. How will you insure that any risks to subjects are minimized? If there are potential
risks, describe what will be done to minimize these risks. If there are risks, describe
why the risks to participants are reasonable in relation to the anticipated benefits.
The potential risks involved will be outlined in the Informed Consent form and
include delayed onset muscle soreness (DOMS), which is general muscle soreness
and a common side effect of exercise, that may last two to three days. Other risks
involve injuries that could be sustained during a normal exercise program involving
68
the lower extremity including minor strains and sprains. Any injuries sustained
during testing will be treated by the researcher or the researcher's advisor, both
certified athletic trainers. To minimize the risk of injury, each group of subjects will
be instructed on how to properly warm up and these warm ups will be incorporated
into the ACL injury prevention program. Every exercise will be demonstrated, by the
researcher, to the participants prior to the subjects beginning the exercise. Also, the
researcher or an undergraduate athletic training student, who is certified in first aid
and CPR, will be present for each exercise session to ensure proper form for each
exercise is being implemented to reduce the risk of injury.
b. How will you insure that the selection of subjects is equitable? Take into account
your purpose(s). Be sure you address research problems involving vulnerable
populations such as children, prisoners, pregnant women, mentally disabled persons,
and economically or educationally disadvantaged persons. If this is an in-class
project describe how you will minimize the possibility that students will feel coerced.
The selection of subjects will be done on a volunteer basis. Only students deemed
physically active will be included in the study. Subjects are considered physically
active if they exercise for at least 30 minutes 3 or more times a week. Subjects
recruited for the study will be students in health science classes at California
University of Pennsylvania. Announcements of ability to participate in the study will
be made in health science classes as well as through E-mail. To avoid the feeling of
coercion, students will be assured that they are not required to participate and should
only do so if they desire.
c. How will you obtain informed consent from each participant or the subject’s legally
authorized representative and ensure that all consent forms are appropriately
documented? Be sure to attach a copy of your consent form to the project summary.
An informed consent form, that the students will have ample time to read, will be
signed and completed by the subjects during a meeting to take place before the
implementation of the exercise program. Before the informed consent form is
signed, participants will have ample time to ask any questions they may have. A
copy of the form is attached.
d. Show that the research plan makes provisions to monitor the data collected to insure
the safety of all subjects. This includes the privacy of subjects’ responses and
provisions for maintaining the security and confidentiality of the data.
All data will be collected by the researcher and placed in a secure cabinet known only
to the researcher and research advisor. A key to the cabinet will be in sole possession
of the researcher. Subjects will be assigned a number to maintain confidentiality.
3. Check the appropriate box(es) that describe the subjects you plan to use.
69
Adult volunteers
Mentally Disabled People
CAL University Students
Economically Disadvantaged People
Other Students
Educationally Disadvantaged People
Prisoners
Fetuses or fetal material
Pregnant Women
Children Under 18
Physically Handicapped People
Neonates
4. Is remuneration involved in your project?
5. Is this project part of a grant?
Yes or
Yes or
No
No. If yes, Explain here.
If yes, provide the following information:
Title of the Grant Proposal
Name of the Funding Agency
Dates of the Project Period
6.
Does your project involve the debriefing of those who participated?
Yes or
No
If Yes, explain the debriefing process here.
7. If your project involves a questionnaire interview, ensure that it meets the requirements of
Appendix
in the Policies and Procedures Manual.
70
California University of Pennsylvania Institutional Review Board
Survey/Interview/Questionnaire Consent Checklist (v021209)
This form MUST accompany all IRB review requests
Does your research involve ONLY a survey, interview or questionnaire?
YES—Complete this form
NO—You MUST complete the “Informed Consent Checklist”—skip the remainder
of this form
Does your survey/interview/questionnaire cover letter or explanatory statement include:
(1) Statement about the general nature of the survey and how the data will be
used?
(2) Statement as to who the primary researcher is, including name, phone, and
email address?
(3) FOR ALL STUDENTS: Is the faculty advisor’s name and contact information
provided?
(4) Statement that participation is voluntary?
(5) Statement that participation may be discontinued at any time without penalty
and all data discarded?
(6) Statement that the results are confidential?
(7) Statement that results are anonymous?
(8) Statement as to level of risk anticipated or that minimal risk is anticipated?
(NOTE: If more than minimal risk is anticipated, a full consent form is required—and
the Informed Consent Checklist must be completed)
(9) Statement that returning the survey is an indication of consent to use the data?
(10) Who to contact regarding the project and how to contact this person?
(11) Statement as to where the results will be housed and how maintained? (unless
otherwise approved by the IRB, must be a secure location on University premises)
(12) Is there text equivalent to: “Approved by the California University of
Pennsylvania Institutional Review Board. This approval is effective nn/nn/nn and
expires mm/mm/mm”? (the actual dates will be specified in the approval notice from
the IRB)?
71
(13) FOR ELECTRONIC/WEBSITE SURVEYS: Does the text of the cover letter
or
explanatory statement appear before any data is requested from the participant?
(14) FOR ELECTONIC/WEBSITE SURVEYS: Can the participant discontinue
participation at any point in the process and all data is immediately discarded?
72
California University of Pennsylvania Institutional Review Board
Informed Consent Checklist (v021209)
This form MUST accompany all IRB review requests
Does your research involve ONLY a survey, interview, or questionnaire?
YES—DO NOT complete this form. You MUST complete the
“Survey/Interview/Questionnaire Consent Checklist” instead.
NO—Complete the remainder of this form.
1. Introduction (check each)
(1.1) Is there a statement that the study involves research?
(1.2) Is there an explanation of the purpose of the research?
2. Is the participant. (check each)
(2.1) Given an invitation to participate?
(2.2) Told why he/she was selected.
(2.3) Told the expected duration of the participation.
(2.4) Informed that participation is voluntary?
(2.5) Informed that all records are confidential?
(2.6) Told that he/she may withdraw from the research at any time without
penalty or loss of benefits?
(2.7) 18 years of age or older? (if not, see Section #9, Special Considerations
below)
3. Procedures (check each).
(3.1) Are the procedures identified and explained?
(3.2) Are the procedures that are being investigated clearly identified?
(3.3) Are treatment conditions identified?
4. Risks and discomforts. (check each)
(4.1) Are foreseeable risks or discomforts identified?
(4.2) Is the likelihood of any risks or discomforts identified?
(4.3) Is there a description of the steps that will be taken to minimize any risks or
discomforts?
(4.4) Is there an acknowledgement of potentially unforeseeable risks?
(4.5) Is the participant informed about what treatment or follow up courses of
action are available should there be some physical, emotional, or psychological harm?
(4.6) Is there a description of the benefits, if any, to the participant or to others
that may be reasonably expected from the research and an estimate of the likelihood
of these benefits?
(4.7) Is there a disclosure of any appropriate alternative procedures or courses of
treatment that might be advantageous to the participant?
5. Records and documentation. (check each)
73
(5.1) Is there a statement describing how records will be kept confidential?
(5.2) Is there a statement as to where the records will be kept and that this is a
secure location?
(5.3) Is there a statement as to who will have access to the records?
6. For research involving more than minimal risk (check each),
(6.1) Is there an explanation and description of any compensation and other
medical or counseling treatments that are available if the participants are injured
through participation?
(6.2) Is there a statement where further information can be obtained regarding the
treatments?
(6.3) Is there information regarding who to contact in the event of researchrelated injury?
7. Contacts.(check each)
(7.1) Is the participant given a list of contacts for answers to questions about the
research and the participant’s rights?
(7.2) Is the principal researcher identified with name and phone number and
email address?
(7.3) FOR ALL STUDENTS: Is the faculty advisor’s name and contact
information provided?
8. General Considerations (check each)
(8.1) Is there a statement indicating that the participant is making a decision
whether or not to participate, and that his/her signature indicates that he/she has
decided to participate having read and discussed the information in the informed
consent?
(8.2) Are all technical terms fully explained to the participant?
(8.3) Is the informed consent written at a level that the participant can understand?
(8.4) Is there text equivalent to: “Approved by the California University of
Pennsylvania Institutional Review Board. This approval is effective nn/nn/nn and
expires mm/mm/mm”? (the actual dates will be specified in the approval notice from
the IRB)
9. Specific Considerations (check as appropriate)
(9.1) If the participant is or may become pregnant is there a statement that the
particular treatment or procedure may involve risks, foreseeable or currently
unforeseeable, to the participant or to the embryo or fetus?
(9.2) Is there a statement specifying the circumstances in which the participation
may be terminated by the investigator without the participant’s consent?
(9.3) Are any costs to the participant clearly spelled out?
(9.4) If the participant desires to withdraw from the research, are procedures for
orderly termination spelled out?
74
(9.5) Is there a statement that the Principal Investigator will inform the participant
or any significant new findings developed during the research that may affect them
and influence their willingness to continue participation?
(9.6) Is the participant is less than 18 years of age? If so, a parent or guardian must
sign the consent form and assent must be obtained from the child
Is the consent form written in such a manner that it is clear that the
parent/guardian is giving permission for their child to participate?
Is a child assent form being used?
Does the assent form (if used) clearly indicate that the child can freely refuse
to participate or discontinue participation at any time without penalty or coercion?
(9.7) Are all consent and assent forms written at a level that the intended
participant can understand? (generally, 8th grade level for adults, age-appropriate for
children)
75
California University of Pennsylvania Institutional Review Board
Review Request Checklist (v021209)
This form MUST accompany all IRB review requests.
Unless otherwise specified, ALL items must be present in your review request.
Have you:
(1.0) FOR ALL STUDIES: Completed ALL items on the Review Request Form?
Pay particular attention to:
(1.1) Names and email addresses of all investigators
(1.1.1) FOR ALL STUDENTS: use only your CalU email
address)
(1.1.2) FOR ALL STUDENTS: Name and email address of your
faculty research advisor
(1.2) Project dates (must be in the future—no studies will be approved
which have already begun or scheduled to begin before final IRB approval—
NO EXCEPTIONS)
(1.3) Answered completely and in detail, the questions in items 2a through
2d?
2a: NOTE: No studies can have zero risk, the lowest risk is
“minimal risk”. If more than minimal risk is involved you MUST:
i. Delineate all anticipated risks in detail;
ii. Explain in detail how these risks will be minimized;
iii. Detail the procedures for dealing with adverse outcomes
due to these risks.
iv. Cite peer reviewed references in support of your
explanation.
2b. Complete all items.
2c. Describe informed consent procedures in detail.
2d. NOTE: to maintain security and confidentiality of data, all
study records must be housed in a secure (locked) location ON
UNIVERSITY PREMISES. The actual location (department, office,
etc.) must be specified in your explanation and be listed on any
consent forms or cover letters.
(1.4) Checked all appropriate boxes in Section 3? If participants under the
age of 18 years are to be included (regardless of what the study involves) you
MUST:
(1.4.1) Obtain informed consent from the parent or guardian—
consent forms must be written so that it is clear that the
parent/guardian is giving permission for their child to participate.
(1.4.2) Document how you will obtain assent from the child—
This must be done in an age-appropriate manner. Regardless of
whether the parent/guardian has given permission, a child is
completely free to refuse to participate, so the investigator must
document how the child indicated agreement to participate
(“assent”).
76
(1.5) Included all grant information in section 5?
(1.6) Included ALL signatures?
(2.0) FOR STUDIES INVOLVING MORE THAN JUST SURVEYS,
INTERVIEWS, OR QUESTIONNAIRES:
(2.1) Attached a copy of all consent form(s)?
(2.2) FOR STUDIES INVOLVING INDIVIDUALS LESS THAN 18
YEARS OF AGE: attached a copy of all assent forms (if such a form is used)?
(2.3) Completed and attached a copy of the Consent Form Checklist? (as
appropriate—see that checklist for instructions)
(3.0) FOR STUDIES INVOLVING ONLY SURVEYS, INTERVIEWS, OR
QUESTIONNAIRES:
(3.1) Attached a copy of the cover letter/information sheet?
(3.2) Completed and attached a copy of the
Survey/Interview/Questionnaire Consent Checklist? (see that checklist for
instructions)
(3.3) Attached a copy of the actual survey, interview, or questionnaire
questions in their final form?
(4.0) FOR ALL STUDENTS: Has your faculty research advisor:
(4.1) Thoroughly reviewed and approved your study?
(4.2) Thoroughly reviewed and approved your IRB paperwork? including:
(4.2.1) Review request form,
(4.2.2) All consent forms, (if used)
(4.2.3) All assent forms (if used)
(4.2.4) All Survey/Interview/Questionnaire cover letters (if used)
(4.2.5) All checklists
(4.3) IMPORTANT NOTE: Your advisor’s signature on the review request
form indicates that they have thoroughly reviewed your proposal and verified
that it meets all IRB and University requirements.
(5.0) Have you retained a copy of all submitted documentation for your records?
77
78
Institutional Review Board
California University of Pennsylvania
Psychology Department LRC, Room 310
250 University Avenue
California, PA 15419
instreviewboard@cup.edu
instreviewboard@calu.edu
Robert Skwarecki, Ph.D., CCC-SLP,Chair
Jordan Blair,
Please consider this email as official notification that your proposal titled
“The Effect an ACL Injury Prevention Program on Gluteus Medius Strength
Between Genders” (Proposal #10-029) has been approved by the California
University of Pennsylvania Institutional Review Board as submitted, with
the following stipulation:
-
A screening question or statement indicating that participants must be 18
years of age or older must be present in the consent form and/or
questionnaire.
Once you have made this revision, you may immediately begin data
collection. You do not need to wait for further IRB approval. [At your
earliest convenience, you must forward a copy of the revised consent form
for the Board’s records].
The effective date of the approval is 02-24-2011 and the expiration date is
02-23-2012. These dates must appear on the consent form .
Please note that Federal Policy requires that you notify the IRB promptly
regarding any of the following:
79
(1) Any additions or changes in procedures you might wish for your
study (additions or changes must be approved by the IRB before
they are implemented)
(2) Any events that affect the safety or well-being of subjects
(3) Any modifications of your study or other responses that are
necessitated by any events reported in (2).
(4) To continue your research beyond the approval expiration date of
02-23-2012 you must file additional information to be considered
for continuing review. Please contact instreviewboard@cup.edu
Please notify the Board when data collection is complete.
Regards,
Robert Skwarecki, Ph.D., CCC-SLP
Chair, Institutional Review Board
80
Appendix C3
Trunk Neuromuscular Training Program
81
Trunk Neuromuscular Training Program
Progression 1
Lateral Jump and Hold
Step-Hold
Bosu (Round) Swimmers
BOSU (Round) Double Knee-Hold
Single Leg Lateral Airex Hop-Hold
Single Truck Jump-Soft Landing
Front Lunge
Lunge Jumps
BOSU (FLAT) Double Leg Pelvic
Bridges
Single Leg 90 degree Hop-Hold
BOSU (Round) Lateral Crunch
Box Double Crunch
Swiss Ball Back Hyperextensions
Progression 2
Lateral Jumps
Jump-Single Leg Hold
BOSU (Round) Toe Touch Swimmers
BOSU (Round) Single Knee-Hold
Single Leg Lateral BOSU (Round)
Hop-Hold
Double Tuck Jump
Walking Lunges
Scissor Jumps
BOSU (Flat) Single Leg Pelvic
Bridges
Single Leg 90 degree airex Hop-Hold
Box Lateral Crunch
Box Swivel Double Crunch
Swiss Ball Back Hyperextensions
with Ball Reach
Time
Reps
Sets
8
8
10
R&L Legs
20 sec
4
10
10
10 sec
R&L Legs
R&L Legs
R&L Legs
10
8
10
15
15
Time
Reps
R&L Legs
R&L Legs
Sets
10 sec
8
10
20 sec
8
R&L
R&L
R&L
R&L
Legs
Legs
Legs
Legs
6
10
10 sec
10
R&L Legs
8
10
15
15
R&L Legs
R&L Legs
R&L Legs
82
Progression 3
Lateral Hop and Hold
Hop-Hold
Prone bridge (Elbow and Knees) Hip
Extension Opposite Shoulder Flexion
Swiss Ball Bilateral Kneel
Single Leg Lateral BOSU (Round)
Hop-Hold with Ball Catch
Repeated Tuck Jump
Walking Lunges Unilaterally
weighted
Lunge Jumps unilaterally Weighted
BOSU (Flat) Single Leg Pelvic
Bridges with Ball Hold
Single Leg 90 Degree Airex hop-Hold
Reaction Ball Catch
BOSU (Round) Lateral Crunch with
Ball catch
BOSU (Round) Swivel Ball Touches
(Feet UP)
Swiss Ball Hyperextensions with
Back Fly
Progression 4
Lateral Hops
Hop-Hop-Hold
Prone bridge (Elbow and toes) Hip
Extension
Swiss Ball Bilateral Kneel with
Partner Pertubations
Single Leg 4 Way BOSU (Round) HopHold
Side to Side Barrier Tuck Jumps
Walking Lunges with Plate Crossover
Scissor Jumps Unilaterally Weighted
Supine Swiss Ball Hamstring Curl
Single Leg 180 degree Airex HopHold
Swiss Ball Lateral Crunch
BOSU (Round) double crunch
Swiss Ball Hyperextensions with
Ball Reach Lateral
Time
Reps
Sets
8
8
10
R&L Legs
R&L Legs
4
R&L Legs
10
R&L Legs
10
R&L Legs
R&L Legs
6
R&L Legs
8
R&L Legs
20 sec
10 sec
10 sec
15
15
Time
Reps
10 sec
8
10
Sets
R&L Legs
R&L Legs
R&L Legs
20 sec
3
cycles
R&L Legs
10
R&L Legs
10 sec
10 sec
R&L Legs
10
8
15
15
15
R&L Legs
R&L Legs
R&L Legs
83
Progression 5
Time
X-Hops
Crossover-Hop-Hop-Hold
Prone bridge (Elbow and toes) Hip
Extension opposite shoulder flexion
Swiss Ball Bilateral Kneel with
Lateral Ball Catch
Single Leg 4 Way BOSU (Round) HopHold With Ball Catch
Side to Side Reaction Barrier Tuck
Jumps
Walking Lunges with Unilateral
Shoulder Press
Scissor Jumps with Ball Swivel
Swivel Russian Hamstring Curl
Single Leg 180 degree Airex HopHold Reaction Ball Catch
Swiss Ball Lateral Crunch with Ball
Catch
BOSU (Round) Swivel Double Crunch
Swiss Ball Hyperextensions with
Lateral Ball Catch
Reps
Sets
6
cycles
8
10
R&L Legs
3
cycles
R&L Legs
10
R&L Legs
R&L Legs
R&L Legs
20 sec
10 sec
10 sec
R&L Legs
10
8
R&L Legs
8
R&L Legs
15
15
R&L Legs
1. Lateral Jumping Progression
Phase I – Lateral Jump and Hold
The subject prepares for this exercise by standing with her
feet close together and her knees slightly bent. The
subject should jump laterally over a line keeping her knees
bent and staying close to the line. When they lands on the
opposite side, they should immediately descend into a deep
hold.
Phase II – Lateral Jumps
The subject prepares for this exercise by standing with
their feet close together and knees slightly bent on one
side of the line. The subject should jump sideways over the
line keeping her knees bent and staying close to the line.
84
When the subject lands on the opposite side, they should
immediately redirect back to the initial position. The
subject should repeat this sequence as quickly as they can
while maintaining proper form. When teaching this exercise,
encourage the subject to achieve as many repetitions as
possible in the allotted time by jumping close to the
lines, shortening the ground contact time, and not using
excessive height on the jumps. Do not allow the subject to
perform a double hop on the side of the line. Early in the
training the subject may focus on the line, as their
technique improves encourage them to shift their visual
focus away from the line to outside cues.
Phase III – Lateral Hop and Hold
The subject prepares for this exercise by standing on one
foot and their knee slightly bent. The subject should jump
sideways over a line keeping their knee bent and staying
close to the line. When they land on the opposite side,
they should immediately descend into a single leg deep
hold.
Phase IV – Lateral Hops
The subject prepares for this exercise by standing on one
leg with their knee slightly bent on one side of the line.
The subject should jump sideways over the line keeping
their knee bent and staying close to the line. When the
subject lands on the opposite side, they should immediately
redirect back to the initial position. When teaching this
exercise encourage the subject to achieve as many
repetitions as possible in the allotted time by jumping
close to the lines, shortening the ground contact time, and
not using excessive height on the jumps. Do not allow the
subject to perform a double hop on the side of the line.
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Early in the training the subject may focus on the line, as
her technique improves encourage them to shift their visual
focus away from the line to outside cues.
Phase V – X Hops
The subject begins facing a quadrant pattern standing on a
single limb with their support knee slightly bent. They
will hop diagonally, landing in the opposite quadrant,
maintaining forward stance, and holding the deep knee
flexion landing for three seconds. The subject then hops
laterally into the side quadrant again holding the landing.
Next, the subject will hop diagonally backwards holding the
landing. Finally, they hop laterally into the initial
quadrant holding the landing. The subject should repeat
this figure 8 pattern for the required number of sets.
Encourage the subject to maintain balance during each
landing, keeping her eyes up and their focus away from
their feet.
2. Single-Leg Anterior Progression
Phase I – Step-Hold
The subject starts by taking a quick step forward and
continues by balancing in a deep hold position on the leg
they stepped onto.
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Phase II – Jump-Single Leg Hold
The subject will begin this exercise in the athletic
position. The subject proceeds to jump forward, landing and
balancing on one leg in a deep hold position.
Phase III – Hop-Hold
Starting in a balanced position on one foot, the subject
hops forward, landing and balancing on one leg in a deep
hold position.
Phase IV – Hop-Hop-Hold
The subject hops forward twice quickly, landing and
balancing on one leg in a deep hold position.
Phase V – Crossover-Hop-Hop-Hold
The subject hops forward while alternating legs three times
quickly, landing and balancing on one leg in a deep hold
position.
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3. Prone Trunk Stability Progression
Phase I – BOSU® (Round) Toe Touch Swimmers
The subject begins in a prone position with their abdomen
centered on the round side of the BOSU® and their arms
overhead and legs extended. The subject reaches back with
one arm to touch opposite foot and returns to the
outstretched superman position
Phase II – BOSU® (Round) Swimmers with Partner
Perturbations
The subject begins in prone position with abdomen centered
on the round side of the BOSU® and with their arms overhead
and legs extended. The movement is initiated by elevating
the opposite arm and leg and held for three seconds. A
partner will offer random perturbations by stepping on
different sides of the BOSU® during the exercise.
Phase III – Prone Bridge (Elbows and Knees) Hip Extension
Opposed Shoulder Flexion
The subject begins in prone position with her elbows flexed
and balanced on an Airex pad and knees on the ground. The
movement is initiated by elevating the opposite arm and leg
and held for a single count and finitheyd by returning to
the original position.
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Phase IV – Prone Bridge (Elbows and Toes) Hip Extension
The subject begins in prone position with elbows flexed and
balanced on an Airex pad and toes on the ground. The
movement is initiated by elevating the each leg
individually and held for a single count and finished by
returning to the original position.
Phase V – Prone Bridge (Elbows and Toes) Hip Extension
Opposite Shoulder Flexion
The subject begins in prone position with elbows flexed and
balanced on an Airex pad and toes on the ground. The
movement is initiated by elevating the opposite arm and leg
and held for a single count and finished by returning to
the original position.
4. Kneeling Trunk Stability Progression
Phase I – BOSU® (Round) Double Knee-Hold
The subject begins this exercise by balancing in a kneeling
position with their knees on each side of the round side of
the BOSU®. The subject will maintain this balanced position
with the hips slightly flexed for the duration of the
exercise.
89
Phase II – BOSU® (Round) Single Knee-Hold
The subject begins this exercise by balancing in a kneeling
position with one knee directly in the middle of the round
side of the BOSU® and the other knee extended out to the
side. The subject will maintain this balanced position with
the hip slightly flexed for the duration of the exercise.
Phase III – Swiss Ball Bilateral Kneel
The subject kneels and balances on Swiss ball with feet off
the ground. A spotter should be available at all times in
front of the subject
Phase IV – Swiss Ball Bilateral kneel with Partner
Perturbations
The subject kneels and balances on Swiss ball with their
feet off of the ground. Once the subject is stabilized a
partner can perturb the ball by kicking in unanticipated
directions. A spotter should be available at all times in
front of the subject.
90
Phase V – Swiss Ball Bilateral Kneel with Lateral Ball
Catch
The subject kneels and balances on Swiss ball with feet off
the ground. A ball should be tossed back and forth with a
partner to increase the difficulty of this exercise. A
spotter should be present next to the subject at all times.
5. Single Leg Lateral Progression
Phase I – Single Leg Lateral AIREX Hop-Hold
Subject starts on one side of the Airex pad and hops
laterally onto the Airex. The subject should maintain
balance and hold the knee in a flexed position. The subject
then hops off the other side of the Airex onto the ground,
maintains balance and then repeats the exercise in the
other direction.
Phase II – Single Leg Lateral BOSU® (Round) Hop-Hold
Subject starts on one side of the BOSU® and hops laterally
onto the BOSU®. The subject should maintain balance and
hold the knee in a flexed position. The subject then hops
off the other side of the BOSU® onto the ground, maintains
balance and then repeats the exercise in the other
direction.
91
Phase III – Single Leg Lateral BOSU® (Round) Hop-Hold with
Ball Catch
The subject starts on one side of the BOSU® and hops
laterally onto the BOSU®. The subject should maintain
balance and hold the knee in a flexed position. The subject
then hops off the other side of the BOSU® onto the ground,
maintains balance and then repeats the exercise in the
other direction. The subject is further challenged by
having to catch and return a ball upon each landing.
Phase IV – Single Leg 4 Way BOSU® (Round) Hop-Hold
The subject starts in a single leg athletic position
immediately behind the BOSU®. The subject hops forward onto
the round side of the BOSU® and lands in a balanced
position. After achieving a balanced single leg stance on
the BOSU®, the subject proceeds to hop off the BOSU®
laterally and assumes this same stance on the floor
immediately next to the BOSU®. The subject will then
continue to hop on and off the BOSU®, achieving a balanced
athletic position, in each of the four directions: forward,
backwards, lateral and medial.
Phase V – Single Leg 4 Way BOSU® (Round) Hop-Hold with Ball
Catch
The subject starts in a single leg athletic position
immediately behind the BOSU®. The subject hops forward onto
the round side of the BOSU® and lands in a balanced
position. After achieving a balanced single leg stance on
the BOSU®, the subject proceeds to hop off the BOSU®
laterally and assumes this same stance on the floor
92
immediately next to the BOSU®. The subject will then
continue to hop on and off the BOSU®, achieving a balanced
athletic position, in each of the four directions: forward,
backwards, lateral and medial. A ball should be tossed back
and forth with a partner upon landing to increase the
difficulty of this exercise.
6. Tuck Jump Progression
Phase I - Single Tuck Jump Soft Landing
The subject starts in the athletic position with their feet
shoulder width apart. The subject initiates a vertical jump
with a slight crouch downward while they extends their arms
behind them. The subject then swings their arms forward as
they simultaneously jumps straight up and pulls their knees
up as high as possible. At the highest point of the jump
the subject should be positioned in the air with their
thighs parallel to the ground. On landing, the subject
should land softly, using a toe to mid-foot rocker landing.
The subject should not continue this jump if they cannot
control the high landing force or keep their knees aligned
during landing. If the subject is unable to raise the knees
to the proper height, it may be valuable to instruct them
to “grasp the knees and they bring the thighs to
horizontal.”
Phase II – Double Tuck Jump
Similar to the single tuck jump described above but with an
additional jump performed immediately after the first jump.
The subject should focus on maintaining good form and
minimizing time on the ground between jumps.
93
Phase III – Repeated Tuck Jumps
The subject starts in the athletic position with their feet
shoulder width apart. The subject initiates a vertical jump
with a slight crouch downward while they extends their arms
behind them. The subject then swings their arms forward as
they simultaneously jump straight up and pull their knees
up as high as possible. At the highest point of the jump
the subject should be positioned in the air with their
thighs parallel to the ground. When landing the subject
should immediately begin the next tuck jump.
Phase IV – Side to Side Tuck Jumps
The subject starts in the athletic position with their feet
shoulder width apart. The subject initiates a vertical jump
over a barrier with a slight crouch downward while they
extends their arms behind them. The subject then swings
their arms forward as they simultaneously jump straight up
and pull their knees up as high as possible. At the highest
point of the jump the subject should be positioned in the
air with their thighs parallel to the ground. When landing,
the subject should immediately begin the next tuck jump
back to the other side of the barrier.
Phase V – Side to Side Reaction Barrier Tuck Jumps
The subject starts in the athletic position with their feet
shoulder width apart. The subject initiates a vertical jump
over a barrier with a slight crouch downward while they
extend their arms behind them. The subject then swings
their arms forward as they simultaneously jump straight up
and pull their knees up as high as possible. At the highest
point of the jump the subject should be positioned in the
94
air with their thighs parallel to the ground. When landing
the subject should immediately begin the next tuck jump.
When prompted, the subject should jump to the other side of
the barrier without breaking rhythm.
7. Lunge Progression
Phase I – Front Lunges
The subject begins by stepping forward from a standing
position. The step should be exaggerated in length to the
point that their front leg is positioned with the knee
flexed to 90° and the lower leg completely vertical. The
back leg should be as straight as possible and the torso
upright. Emphasis should be placed on getting the hips as
low as possible while maintaining the previously described
body position. The exercise is completed by driving off the
front leg and returning to the original position.
Phase II – Walking Lunges
The subject performs a lunge and instead of returning to
the start position they step through with the back limb and
proceed forward with a lunge on the opposite limb.
Encourage the subject to lunge their front limb far enough
out so that their knee does not advance beyond their ankle
during the exercise. An alternative coaching method is to
instruct the subject to attempt to maintain a constant low
center of gravity and roll through the lunges. This
increases the intensity of the exercise and attempts to
mimic motions frequently occurring in sports.
95
Phase III – Walking Lunges Unilaterally Weighted
The subject performs a lunge and instead of returning to
the start position they steps through with the back limb
and proceeds forward with a lunge on the opposite limb
while holding a dumbbell in one hand. Encourage the subject
to lunge their front limb far enough out so that their knee
does not advance beyond her ankle during the exercise. This
exercise is then repeated with the dumbbell in the opposite
hand.
Phase IV – Walking Lunges with Plate Crossover
The subject performs a lunge and instead of returning to
the start position they steps through with the back limb
and proceeds forward with a lunge on the opposite limb
while reaching with a weight plate to the open side of the
body. Encourage the subject to lunge their front limb far
enough out so that their knee does not advance beyond her
ankle during the exercise.
Phase V – Walking Lunges with Unilateral Shoulder Press
The subject performs a lunge and instead of returning to
the start position they steps through with the back limb
and proceeds forward with a lunge on the opposite limb
while pressing a dumbbell above her head. The weight should
move up and down with the same tempo and direction as the
lunge. Encourage the subject to lunge their front limb far
96
enough out so that their knee does not advance beyond their
ankle during the exercise.
8. Lunge Jump Progression
Phase I – Lunge Jumps
The subject starts in an extended stride position with
the hips pushed forward, and the front knee positioned
directly above the ankle and flexed to 90°. The back leg
is fully extended at the hip and knee providing minimal
support for the stance. The subject should jump
vertically off of the front support leg maintaining the
starting position during flight and landing. The jump is
repeated as quickly as possible while still achieving
maximum vertical height. To coach this jump, encourage
the subject to keep the back leg straight and use it only
for balance support. Vertical power is obtained by the
front leg. Stance support percentages are approximately
80% for the front leg and 20% for the back.
Phase II – Scissor Jumps
The subject starts in an extended stride position with the
hips pushed forward, and the front knee positioned directly
above the ankle and flexed to 90°. The back leg is fully
extended at the hip and knee providing minimal support for
the stance. The subject should jump vertically off of the
front support leg and switch the position of the legs while
in flight. The jump is repeated as quickly as possible
while still achieving maximum vertical height. The subject
will be jumping off alternate legs on each jump during this
exercise.
97
Phase III – Lunge Jumps Unilaterally Weighted
The subject starts in an extended stride position with
their hips pushed forward, and the front knee positioned
directly above the ankle and flexed to 90°. The back leg is
fully extended at the hip and knee providing minimal
support for the stance. The subject should jump vertically
off of the front support leg maintaining the starting
position during flight and landing. The jump is repeated as
quickly as possible while still achieving maximum vertical
height. To unilaterally weight this exercise a dumbbell
should be held in one hand. This exercise is then repeated
with the dumbbell in the opposite hand.
Phase IV – Scissor Jumps Unilaterally Weighted
The subject starts in an extended stride position with the
hips pushed forward, and the front knee positioned directly
above the ankle and flexed to 90°. The back leg is fully
extended at the hip and knee providing minimal support for
the stance. The subject should jump vertically off of the
front support leg and switch the position of the legs while
in flight. The jump is repeated as quickly as possible,
while still achieving maximum vertical height. To
unilaterally weight this exercise, a dumbbell should be
held in one hand. The subject will be jumping off alternate
legs on each jump during this exercise. This exercise is
then repeated with the dumbbell in the opposite hand.
98
Phase V – Scissor Jumps with Ball Swivel
The subject starts in an extended stride position with the
hips pushed forward, and the front knee positioned directly
above the ankle and flexed to 90°. The back leg is fully
extended at the hip and knee providing minimal support for
the stance. The subject should jump vertically off of the
front support leg and switch the position of the legs while
in flight. The jump is repeated as quickly as possible
while still achieving maximum vertical height. To
unilaterally weight this exercise, a medicine ball should
be swiveled to the open side of the body during each jump.
The subject will be jumping off alternate legs
9. Hamstring Specific Progression
Phase I – BOSU® (Flat) Pelvic Bridge
The subject lays supine with their hip and knees flexed and
their feet planted on the flat side of the BOSU®. The
subject then extends their hips and elevates their trunk
off the ground to execute a pelvic bridge. This position
should be held for 3 seconds prior to repeating the next
repetition.
Phase II – BOSU® (Flat) Single Leg Pelvic Bridge
The subject lays supine with their hip and knees flexed and
99
a single foot planted on the flat side of the BOSU® and the
contralateral (opposite) leg fully extended. The subject
then extends their hips and elevates their trunk off the
ground to execute a pelvic bridge. This position should be
held for 3 seconds prior to repeating the next repetition.
Phase III – BOSU® (Flat) Single Leg Pelvic Bridge
The subject lays supine with their hip and knees flexed and
a single foot planted on the flat side of the BOSU® and the
contralateral (opposite) leg fully extended holding a ball
directly above her in her hands. The subject then extends
their hips and elevates their trunk off the ground to
execute a pelvic bridge. This position should be held for 3
seconds prior to repeating the next repetition.
Phase IV – Supine Swiss Ball Hamstring Curl
The subject lays supine with their hip and knees flexed
with both heels planted on top of a Swiss ball. The subject
then extends their hips and elevates their trunk off the
ground while pulling her heels in to her buttocks.
Phase V – Russian Hamstring Curl with Lateral Touch
The subject begins in a kneeling position with a partner
providing foot support and torso support (with band
100
assistance). The subject extends at the knee to lower their
torso towards the ground. Once touching the BOSU® with
their chest the subject swivels their trunk and returns to
the original position. The coach should provide enough
assistance so that the exercise can be performed without
flexing at the hip.
10. Single Leg Rotatory progression
Phase I – Single Leg 90° Hop-Hold
The starting position for this jump is with the subject in
a semi-crouched position on the single limb being trained.
The jump should focus on attaining maximum height while
maintaining good form upon landing. During the flight
phase, the subject should rotate 90°. The landing occurs on
the same leg and should be performed with deep knee flexion
(to 90°). The landing should be held for a minimum of three
seconds to be counted as a successful landing. Coach this
jump with care to protect the subject from injury. Start
the subject with a sub maximal effort so they can
experience the difficulty of the jump. Continue to increase
the intensity of the jump as the subject improves their
ability to stick and hold the final landing. Have the
subject keep their focus away from their feet, to help
prevent too much forward lean.
Phase II – Single Leg 90° AIREX Hop-Hold
The starting position for this jump is with the subject in
a semi-crouched position on the single limb being trained.
101
The jump should focus on attaining maximum height while
maintaining good form upon landing. During the flight phase
the subject should rotate 90°. The landing occurs on the
same leg and should be performed with deep knee flexion (to
90°). The landing should be held for a minimum of three
seconds on an AIREX pad to be counted as a successful
landing. Coach this jump with care to protect the subject
from injury.
Phase III – Single Leg 90° Hop-Hold Reaction Ball Catch
The starting position for this jump is with the subject in
a semi-crouched position on the single limb being trained.
The jump should focus on attaining maximum height while
maintaining good form upon landing. During the flight phase
the subject should rotate 90°. The landing occurs on the
same leg and should be performed with deep knee flexion (to
90°). The landing should be held for a minimum of three
seconds on an AIREX pad to be counted as a successful
landing. Upon landing a ball will be passed back and forth
with the subject to increase the difficulty of a successful
landing.
Phase IV – Single Leg 180° AIREX Hop-Hold
The starting position for this jump is with the subject in
a semi-crouched position on the single limb being trained.
The jump should focus on attaining maximum height while
maintaining good form upon landing. During the flight phase
the subject should rotate 180°. The landing occurs on the
same leg and should be performed with deep knee flexion (to
90°). The landing should be held for a minimum of three
seconds on an AIREX pad to be counted as a successful
landing.
102
Phase V – Single Leg 180° AIREX Hop-Hold Reaction Ball
Catch
The starting position for this jump is with the subject in
a semi-crouched position on the single limb being trained.
The jump should focus on attaining maximum height while
maintaining good form upon landing. During the flight phase
the subject should rotate 180°. The landing occurs on the
same leg and should be performed with deep knee flexion (to
90°). The landing should be held for a minimum of three
seconds on an AIREX pad to be counted as a successful
landing. Upon landing a ball will be passed back and forth
with the subject to increase the difficulty of a successful
landing.
11. Lateral Trunk Progression
Phase I – BOSU® (Round) Lateral Crunch
The subject starts lying on their side with their hip
located in the center of the round side of the BOSU®. The
subject’s feet and legs must be anchored during this
exercise by the trainer or a stationary object. The subject
will proceed to bend laterally at the waist back and forth
for the prescribed repetitions.
Phase II – Box Lateral Crunch
Subject starts in a supine position on a plyo box with arms
placed on the back of the head. The subject flexes their
trunk simultaneous with their flexion. As the trunk and hip
are maximally flexed, the subject rotates at the trunk
touching each elbow to the opposite knee.
103
Phase III – BOSU® (Round) Lateral Crunch with Ball Catch
Subject starts lying on side with hip located top of the
round side of a BOSU®. The subject’s feet and legs must be
anchored during this exercise by the trainer or a
stationary object. The subject will proceed to bend
laterally at the waist back and forth for the prescribed
repetitions. A ball should be tossed back and forth with a
partner to increase the difficulty of this exercise.
Phase IV – Swiss Ball Lateral Crunch
Subject starts lying on side with hip located top of a
Swiss ball. The subject’s feet and legs must be anchored
during this exercise by the trainer or a stationary object.
The subject will proceed to bend laterally at the waist
back and forth for the prescribed repetitions.
Phase V – Swiss Ball Lateral Crunch with Ball Catch
Subject starts lying on side with hip located top of a
Swiss ball. The subject’s feet and legs must be anchored
during this exercise by the trainer or a stationary object.
The subject will proceed to bend laterally at the waist
back and forth for the prescribed repetitions. A ball
should be tossed back and forth with a partner to increase
the difficulty of this exercise.
12. Trunk Flexion Progression
Phase I – Box Double Crunch
104
The subject starts out supine on a plyometric box or
similar object and flexes their trunk simultaneous with hip
flexion.
Phase II – Box Swivel Double Crunch
Subject starts in a supine position on a plyo box with arms
placed across chest. The subject flexes their trunk
simultaneous with hip flexion. As the trunk and hip are
maximally flexed, the subject rotates at the trunk touching
each elbow to the opposite knee.
Phase III – BOSU® (Round) Swivel Ball Touches (Feet up)
Subject starts sitting on the round side of a BOSU® holding
a medicine ball. The subject will proceed to swivel at the
trunk to touch the medicine ball to the floor for each
repetition.
Phase IV – BOSU® (Round) Double Crunch
Subject starts sitting on the round side of a BOSU®. The
subject flexes their trunk simultaneous with hip flexion.
105
Phase V – BOSU® (Round) Swivel Double Crunch
Subject starts sitting on the round side of a BOSU®. The
subject flexes her trunk simultaneous with hip flexion. As
the trunk and hip are maximally flexed, the subject rotates
at the trunk touching each elbow to the opposite knee.
13. Trunk Extension Progression
Phase I – Swiss Ball Back Hyperextensions
The subject begins in a prone position on the Swiss ball
with their hips centered on top of the Swiss ball and a
partner anchoring their feet to the floor. The movement is
initiated by extending htheirer hips and lower back to
bring the subject into a position of slight hyperextension.
The position should be maintained for a short pause and
then returned to the flexed position.
Phase II – Swiss Ball Back Hyperextensions with Ball Reach
The subject begins in a prone position on the Swiss ball
with their hips centered on top of the Swiss ball and a
partner anchoring their feet to the floor. The movement is
initiated by extending hips and lower back to bring the
subject into a position of slight hyperextension. While
performing this motion the subject will also extend and
return a medicine ball from the chest to full shoulder and
elbow extension and back to the chest.
Phase III – Swiss Ball Hyperextensions with Back Fly
106
The subject begins in a prone position on the Swiss ball
with their hips centered on top of the Swiss ball and a
partner anchoring their feet to the floor. The movement is
initiated by extending hips and lower back to bring the
subject into a position of slight hyperextension. The
position should be maintained while the subject brings
dumbbells out to the side similar to a back fly exercise.
Phase IV – Swiss Ball Hyperextensions with Ball Reach
Lateral
The subject begins in a prone position on the Swiss ball
with their hips centered on top of the Swiss ball and a
partner anchoring their feet to the floor. The movement is
initiated by extending hips and lower back to bring the
subject into a position of slight hyperextension. The
position should be maintained while the subject brings a
medicine ball above their head and slightly to the side.
Phase V – Swiss Ball Hyperextensions with Lateral Ball
Catch
The subject begins in a prone position on the Swiss ball
with their hips centered on top of the Swiss ball and a
partner anchoring their feet to the floor. The movement is
initiated by extending hips and lower back to bring the
subject into a position of slight hyperextension. The
position should be maintained while the subject brings a
medicine ball above her head and slightly to the side. A
ball should be tossed back and forth with a partner to
increase the difficulty of this exercise
107
Appendix C4
Physical Activity Readiness Questionnaire
108
Physical Activity Readiness Questionnaire (PAR-Q) and You
Regular physical activity is fun and healthy, and increasingly more
people are starting to become more
active every day. Being more active is very safe for most people.
However, some people should check with
their doctor before they start becoming much more physically active.
If you are planning to become much more physically active than you
are now, start by answering the
seven questions in the box below. If you are between the ages of 15
and 69, the PAR-Q will tell you if you
should check with your doctor before you start. If you are over 69
years of age, and you are not used to being
very active, check with your doctor.
Common sense is your best guide when you answer these questions.
Please read the questions carefully
and answer each one honestly:
YES NO
..1. Has your doctor ever said that you have a heart condition and
that you should only do physical activity recommended by a doctor?
..2. Do you feel pain in your chest when you do physical activity?
..3. In the past month, have you had chest pain when you were not
doing physical activity?
..4. Do you lose your balance because of dizziness or do you ever
lose consciousness?
..5. Do you have a bone or joint problem that could be made worse by
a change in your physical activity?
..6. Is your doctor currently prescribing drugs (for example, water
pills) for your blood pressure or heart condition?
..7. Do you know of any other reason why you should not do physical
activity?
NO to all questions Delay becoming much more active:
.If you are not feeling well because of a temporary illness such as
a cold or a fever – wait until you feel better; or
.If you are or may be pregnant – talk to your doctor before you
start becoming more active.
Please note: If your health changes so that you then answer YES to
any of the above questions, tell your fitness or health
professional.
Ask whether you should change your physical activity plan if you
answered: YES to one or more questions
If you answered NO honestly to all PAR-Q questions, you can be
reasonably sure that you can:
.Start becoming much more physically active – begin slowly and build
up gradually. This is the safest and easiest way to go.
109
.Take part in a fitness appraisal – this is an excellent way to
determine your basic fitness so that you can plan the best way for
you to live actively.
Talk to your doctor by phone or in person BEFORE you start becoming
much more physically active or BEFORE you have a fitness appraisal.
Tell your doctor about the PAR-Q and which questions you answered
YES.
.You may be able to do any activity you want – as long as you start
slowly and build up gradually. Or, you may need to restrict your
activities to those which are safe for you. Talk with your doctor
about the kinds of activities you wish to participate in and follow
his/her advice.
.Find out which community programs are safe and helpful for you.
Informed use of the PAR-Q: Reprinted from ACSM’s Health/Fitness
Facility Standards and Guidelines, 1997 by American College of
Sports Medicine
110
Appendix C5
Demographic Information
111
Demographic Information
Subject #_______
Age: __________________________
Year school: __________________
Gender:
Male or Female (Circle one)
Do you participate in Physical activity for 30 minutes at
least three times a week? Yes or No
(Circle One)
Which leg do you kick a ball with?
Right or Left (Circle One)
Have you sustained a lower extremity injury within the past
6 months?
Yes
Or
No
(Circle One)
Do you suffer from any neuromuscular disorders that you
know of?
Yes
Or
No
(Circle One)
Do you have any balance problems?
Yes
Or
No
(Circle One)
Has a doctor ever told you to not exercise?
Yes
Or
No
(Circle One)
Do you have any other health conditions?
Yes
Or
No
(Circle One)
If Yes, please
explain:___________________________________________________
___________________________________________________________
___________________________________________________________
___________
112
Appendix C6
Subject Testing Sheet
113
Subject Testing Sheet
Subject #_______
Gender_______
Group_______
Gluteus Medius Peak Force (lbs)
Distance from hip to knee__________m
Weight_________(lbs)/ =___________kg
Practice Trial
Trial 1
Trial 2
Trial 3
Mean Peak
force
Left
Leg
Right
Leg
Equation
Left Mean Peak Force (____________lbs) x 4.45 = ______________N
Right Mean Peak Force (______________lbs) x 4.45=_______________N
Gluteus Medius Peak Force (lbs)
Distance from hip to knee__________m
Weight_________(lbs)/ =___________kg
Practice Trial
Trial 1
Trial 2
Trial 3
Left
Leg
Right
Leg
Equation
Left Mean Peak Force (____________lbs) x 4.45 = ______________N
Right Mean Peak Force (______________lbs) x 4.45=_______________N
Mean Peak
force
114
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120
ABSTRACT
Title:
THE EFFECT OF AN ACL INJURY PREVENTION
PROGRAM ON GLUTEUS MEDIUS STRENGTH BETWEEN
GENDERS
Researcher:
Jordan Blair
Advisor:
Dr. Shelly DiCesaro
Date:
May 2011
Research Type: Master’s Thesis
Context:
Current research indicates the gluteus
medius as an important muscle in the
prevention of ACL injuries. Previous
studies have not examined the effects of an
ACL injury prevention programs’ effect on
gluteus medius strength, nor if there is a
difference in benefits received from an ACL
injury prevention program between genders.
Objective:
The purpose of this study was to examine the
effect of an ACL injury prevention program
on gluteus medius strength as well as
strength gains from the implementation of
the program between males and females.
Design:
Quasi-experimental pre-test and post-test.
Setting:
Testing was performed in a controlled
laboratory setting by the researcher.
Participants:
Twenty-four physically active college
students (male=12, female=12) that were
injury free volunteered for this study.
Interventions: Subjects were randomly placed into an
experimental or control group. All
subjects’ gluteus medius strength was tested
bilaterally at the beginning and end of a
six week period in which the experimental
group underwent an ACL injury prevention
training protocol for 12 sessions twice a
week.
121
Main Outcome Measures:
Gluteus medius strength was assessed at the
end of the six weeks and compared between
experimental and control groups as well as
males and females in the experimental group.
Results:
A significant difference in gluteus medius
strength was found between the experimental
and control groups (t = 2.697, p = .016).
There was not a significant difference in
gluteus medius strength between genders in
the experimental group (t = -0.665, p =
0.527).
Conclusion:
The implementation of a six week ACL injury
prevention program significantly improved
average gluteus medius strength, while
average gluteus medius strength was not
significantly difference between males and
females in the experimental group. This
suggests males and females benefit similarly
from this ACL injury prevention program and
the widespread use of this ACL injury
prevention program may potentially decrease
ACL injuries
Word Count:
339
MEDIUS STRENGTH BETWEEN GENDERS
A THESIS
Submitted to the Faculty of the School of Graduate Studies
and Research
of
California University of Pennsylvania in partial
fulfillment of the requirements for the degree of
Master of Science
by
Jordan Blair
Research Advisor, Dr. Shelly DiCesaro
California, Pennsylvania
2011
i
ii
ACKNOWLEDGEMENTS
I would like to take this opportunity to thank
everyone who made this thesis possible.
First and foremost
I would like to thank my advisor Shelly DiCesaro.
Without
your constant help, I would not have made it this far.
I
would also like to thank Tom West for taking a chance on
student from The Rock.
Without your help and encouragement
throughout this year, I would probably still be sitting in
your research methods class.
Thanks are due to Dr. Edwin
Zuchelkowski as well for your encouragement and belief in
my abilities to complete this study.
My whole committee
deserves to be recognized for placing an unprecedented
amount of faith in me and for allowing me to perform a
study that was something I truly wanted to do.
I would also like to thank my classmates and
additional faculty at California University of
Pennsylvania.
It was a long year, but definitely one that
has yielded friendships.
Additionally I would like to
thank Regis Visconti and Emily Obenauf for their assistance
during my study.
Special Acknowledgment is due to Troy Baxendell for
the inspiration for this study.
Thank you for your
continuous support not only for this study, but for me as a
iii
professional.
I am proud to call you a mentor as well as a
friend.
Finally I would like to thank my family and my
girlfriend for their endless support.
would not have direction in my life.
Without all of you I
I love all of you.
iv
TABLE OF CONTENTS
Page
SIGNATURE PAGE. . . . . . . . . . . . . . . . . i
AKNOWLEDGEMENTS . . . . . . . . . . . . . . . . ii
TABLE OF CONTENTS
LIST OF TABLES
INTRODUCTION
METHODS
. . . . . . . . . . . . . . . iv
. . . . . . . . . . . . . . . . vii
. . . . . . . . . . . . . . . . . 1
. . . . . . . . . . . . . . . . . . . 4
Research Design
. . . . . . . . . . . . . . . 4
Subject . . . . . . . . . . . . . . . . . . . 5
Preliminary Research. . . . . . . . . . . . . . 6
Instruments . . . . . . . . . . . . . . . . . 6
Procedures
. . . . . . . . . . . . . . . . . 7
Hypotheses. . . . . . . . . . . . . . . . . . 9
Data Analysis
RESULTS
. . . . . . . . . . . . . . . . 10
. . . . . . . . . . . . . . . . . . . 10
Demographic Data . . . . . . . . . . . . . . . 10
Hypothesis Testing
. . . . . . . . . . . . . . 11
Additional Findings . . . . . . . . . . . . . . 13
DISCUSSION . . . . . . . . . . . . . . . . . . 16
Discussion of Results . . . . . . . . . . . . . 16
Conclusion. . . . . . . . . . . . . . . . . . 23
Recommendations. . . . . . . . . . . . . . . . 24
v
REFERENCES . . . . . . . . . . . . . . . . . . 26
APPENDICES . . . . . . . . . . . . . . . . . . 30
APPENDIX A: Review of Literature
Introduction
. .
. . . . . . . 31
. . . . . . . . . . . . . . . 32
Noncontact ACL Injuries
. . . . . . . . . . . . 33
Incidence . . . . . . . . . . . . . . . . . 34
Anatomy . . . . . . . . . . . . . . . . . . . 38
Anatomy Involved In ACL Injury . . . . . . . 39
Role of the Gluteus Medius . . . . . . . . . . 42
Difference between Genders . . . . . . . . . . 42
Mechanical Alterations . . . . . . . . . . . . . 48
Prevention Programs . . . . . . . . . . . . . . 49
Components
. . . . . . . . . . . . . . . . 50
Previous Results . . . . . . . . . . . . . . 50
Use of Prevention Programs . . . . . . . . . . 52
Summary . . . . . . . . . . . . . . . . . . . 54
APPENDIX B: The Problem . . . . . . . . . . . . . 55
Statement of the Problem . . . . . . . . . . . . 56
Definition of Terms . . . . . . . . . . . . . . 56
Basic Assumptions . . . . . . . . . . . . . . . 57
Limitations of the Study . . . . . . . . . . . . 57
Significance of the Study
. . . . . . . . . . . 58
APPENDIX C: Additional Methods . . . . . . . . . . 60
Informed Consent Form (C1) . . . . . . . . . . . 61
vi
IRB: California University of Pennsylvania (C2) . . . 64
Trunk Neuromuscular Training Program (C3) . . . . . 80
PAR-Q(C4) . . . . . . . . . . . . . . . . . . 107
Demographic Information (C5)
. . . . . . .
. . . 110
Subject Testing Sheet (C6) . . . . . . . . . . . 112
REFERENCES . . . . . . . . . . . . . . . . . . 114
ABSTRACT . . . . . . . . . . . . . . . . . . . 120
vii
LIST OF TABLES
Table
Title
Page
1
Demographic Data of All Subjects . . . . . 11
2
GMS difference between the Training and
Control Groups . . . . . . . . . . . . 12
3
GMS Difference between Males and Females in the
Training group . . . . . . . . . . . . 13
4
Dominant leg GMS Change between the Training and
Control Groups . . . . . . . . . . . . 13
5
Non-Dominant leg GMS Change between the Training
and Control Groups
6
. . . . . . . . . . 14
GMS difference between Dominant and
Non-Dominant Legs in the Training Group . . 15
7
Average GMS Difference Compared to Days
Missed . . . . . . . . . . . . . . . 15
1
INTRODUCTION
Anterior cruciate ligament (ACL) injuries have been
estimated to account from 75,000 to 250,000 knee injuries
per year.1
While this does not make it an epidemic, the
recovery time associated with this injury coupled with a
higher incidence rate among females makes it one of the
most ubiquitous injuries in the current athletic landscape.
Due to the nefarious reputation of ACL injuries, there has
been a copious amount of research conducted to advance the
prevention of non-contact ACL (NCACL) injuries.
Non-contact ACL injuries account for approximately 70%
of all ACL injuries that occur.
The etiology of non-
contact ACL injuries is still largely unknown, but a common
mechanism of injury is a valgus collapse at the knee.1
A
valgus collapse of the knee is characterized by internal
rotation of the femur, knee valgus, and ankle pronation.
The risk factors for this injury have been identified as
environmental, anatomical, hormonal, and biomechanical.2-4
Anatomical, biomechanical, and hormonal factors are
considered to be intrinsic because these are factors that
are within the patient.
Environmental factors are
considered to be extrinsic because they consist of factors
outside of the patient and, have potential to be
2
controlled.
These situations can range from weather
conditions to playing surfaces to types of shoes worn by
the athlete.
Analysis of studies on the incidence of ACL injuries
place female athletes at a two to six times higher rate of
NCACL injury when compared to males.1,4-7
Due to this
discrepancy, there has been an abundance of research
performed to find the cause of this higher incidence rate.
The results of available research point to five major
gender influences differences that seem to influence ACL
injuries in females, including anatomical differences
between genders,8 increased knee valgus angle,9-14 internal
rotation at the tibia,15 hormonal influences,16-18 and muscle
activation patterns.19,20
The gluteus medius has been
identified as one of the key muscles in the prevention of
patellofemoral injuries, and of the five major gender
influences, the gluteus medius is a factor in knee valgus,
internal rotation, and muscle activation.21
The identification of the higher incidence rates in
female NCACL injuries created a push for the development of
ACL injury prevention programs.
While there have been
multiple techniques used in the past, the most recent and
successful ACL injury prevention programs utilize
neuromuscular training.22-25
These programs implement a
3
combination of lower body strengthening and plyometrics
that improve gluteus medius strength and muscle activation
strategies while also improving the strength of surrounding
musculature.
The purpose of this study is to examine the effect of
a current ACL injury prevention program on gluteus medius
strength in males and females.
It is important to examine
if this program provides the benefit of gluteus medius
strengthening as well as attempt to identify if males and
females share similar gluteus medius strength gains from
the implementation of the program.
Previous research has
shown the need for hip abductor strengthening to prevent
NCACL injuries.9-14,22-25 Recognition of an ACL injury
prevention program’s effectiveness may lead to an increase
in the use of the program at all levels of athletics, which
in turn may lead to a decrease in the incidence of NCACL
injuries suffered by males and females.
4
METHODS
Research Design
This research study utilized a quasi-experimental pretest and post-test design using twelve male and twelve
female subjects between the ages of 18 and 26 who were
considered physically active.
Subjects were considered
physically active if they participated in physical activity
at a moderate intensity for 30 minutes at least 3 times a
week.
The independent variables for the study were gender
and ACL prevention program or control group assignment.
The dependent variable was gluteus medius strength.
Gluteus medius strength was measured using the Lafayette
Manual Muscle Test System (MMTS).
Results were compared
between groups to observe the effect between the program
and control group.
Results also compared the program’s
effect between genders.
Manual Muscle Testing System
(MMTS) pre-test measurement provided a baseline from which
effects of the program and control group were observed.
5
Subjects
The subjects consisted of 24 physically active male
and female college student volunteers between the ages of
18 and 26.
Participants were considered physically active
if they participated in physical activity at a moderate
intensity for at least 30 minutes three times a week.
All
subjects in the study signed an Informed Consent Form
(Appendix C1), a Physical Activity Readiness –
Questionnaire (Appendix C3), as well as a Demographic Sheet
(Appendix C5) prior to participation in the study.
Subjects were instructed to sign the Informed Consent Form
only if they had read through it, understood the study, and
had presented any questions to the researcher.
Subjects
were randomly placed in a study group so that there were no
more than half the number in the control group that was in
the experimental group.
Each participant’s identity
remained confidential and was not included in the study.
Participants who had been diagnosed with a lower extremity
injury within the past six months, identified through the
demographic sheet, were excluded from this study as those
with recent injury may not be ready to participate in an
injury prevention program.
6
Preliminary Research
Preliminary research for this study was conducted to
familiarize the researcher with the MMTS and to determine
the amount of time the muscle testing procedure as well as
the exercise program took to complete.
Two subjects, a
male and a female, were tested for gluteus medius strength
and then led through the ACL injury prevention program.
The researcher looked for the subject’s ability to
understand directions on how to perform each exercise and
the amount of time muscle testing took, as well as the
amount of time needed for completion of the exercise
program.
Instruments
The instruments used in this study were the Lafayette
Manual Muscle Test System as well as assorted exercise
equipment.
The Lafayette Manual Muscle Test system (MMTS)
is a handheld dynamometer that provides an objective way to
measure the strength of a muscle.
The reliability of
dynamometers has been reported as high.26
The following
formula will be used to determine strength of the gluteus
7
medius.
Torque=(Force in Newtons) x (Distance in meters),
Strength=(Torque/Body weight in kg)27
Procedure
The study began with the researcher holding an
introductory meeting with the participants to discuss the
requirements of the study as well as the procedures for the
ACL injury prevention program.
Subjects were informed of
the anticipated time frame for the study as well as the
amount of time the ACL injury prevention program would
take.
Subjects were then offered the Informed Consent Form
once all questions were answered and the researcher had
covered all aspects of the study pertinent to the subjects.
Subjects were then given a sheet to sign up for a time in
which baseline testing was performed.
Testing took no more
than twenty minutes and was done prior to the first day of
the experimental groups exercise session.
On the first day of the experimental group’s exercise
session, each exercise was demonstrated so that the
subjects were aware of proper technique and form.
Packets
with each exercise’s description and pictures were provided
to the participants to ensure an information source was
present if a subject was unsure of technique or form.
8
After the first exercise session, specific times for each
subsequent, were assigned.
Either the researcher or an
approved student from California University of
Pennsylvania’s Athletic Training Education Program, who was
trained in the proper techniques of the exercises, was
present at each session.
Attendance logs were also
maintained during the study to ensure compliance within the
experimental group.
Data from subjects missing more than
two exercise sessions or two sessions in a row were not
included in the study.
Post-tests occurred no later than
one week following each subject’s final exercise session.
Trunk Neuromuscular Training
The trunk neuromuscular training (TNT) program was
developed by Myer et al23 to focus on core musculature as
well as the hip stabilizers to decrease the risk of ACL
injury in females. The training sessions were conducted two
days per week for six weeks as per modified recommendations
of the authors.
25 minutes.
phases.
Each training session lasted approximately
The program consists of five progression
Progressions were implemented once a participant
demonstrated mastery of each exercise in a given phase.
Each phase consisted of 13 exercises that gradually build
in intensity.
Each phase followed the subsequent exercise
9
progression: lateral jump and hold, step-hold, BOSU
swimmers, DOSU double knee-hold, single leg lateral Airex
hop-hold, single tuck jump-soft landing, front lunges,
lunge jumps, BOSU double leg pelvic bridges, single leg 90
degree hop-hold, BOSU lateral crunch, box double crunch,
and Swiss ball back hyperextensions.
Since a warm up was
not specified in the program, a dynamic warm up consisting
of a slow jog for 30 seconds, toe walks for 10 yards,
straight leg kicks for 10 yards, leg swings for 30 seconds,
high knees for 10 yards, and butt-kicks for 10 yards were
implemented to reduce the risk of injury.
Hypotheses
The following hypotheses were based on previous
research and the researcher’s intuition based on a review
of the literature.
1. The subjects placed in the Trunk Neuromuscular
Training program will enhance gluteus medius strength
significantly more than the subjects placed in the
control group.
2. Females placed in the Trunk neuromuscular Training
Program will significantly increase their gluteus
medius strength when compared to males.
10
Data Analysis
All data was analyzed with SPSS version 19.0 with
significance set at an alpha level of 0.05.
The research
hypotheses will be analyzed using an independent T test.
11
RESULTS
Demographic Data
A total of twenty-four subjects (n=24, 12 male, 12
female) participated in this research study.
Two
participants were unable to complete the study
requirements, so data for twenty-two (n=22, 11 males, 11
females) subjects was analyzed for significance.
The
experimental group consisted of twelve subjects (n=12, 7
male and 5 female), and the control group consisted of ten
subjects (n=10, 4 male and 6 female).
All subjects were
volunteers that were physically active, as defined by the
American College of Sports Medicine as exercising at least
three times a week for thirty minutes per session at a
moderate to intense level, and had not suffered a lower
body injury within six months prior to the beginning of the
study. Demographic data, which is demonstrated in Table 1,
was collected by the researcher at the beginning of the
study.
12
Table 1.
Male
Female
Total
Demographic Data of all Subjects
Mean
N
Std.
Deviation
Mean
N
Std.
Deviation
Mean
N
Std.
Deviation
Right
Femur
Length
(m)
0.438
11
0.0318
Left
Femur
length
(m)
0.437
11
0.0313
Weight
(kg)
80.08
11
16.266
Age
(yrs)
21.73
11
1.902
0.412
11
0.0158
0.412
11
0.0152
67.06
11
12.72
20.82
11
1.834
0.425
22
0.0279
0.425
22
0.0273
73.57
22
15.729
21.27
22
1.882
Hypothesis Testing
Statistical analysis was performed on data from all
twenty-two subjects that completed the study with
significance set at an alpha level of ≤ 0.05.
All final
means were measure in Newtons.
Hypothesis 1: The subjects placed in the Trunk
Neuromuscular Training program will enhance gluteus medius
strength (GMS) significantly more than the subjects placed
in the control group.
independent t-test.
Hypothesis 1 was tested utilizing an
Average GMS comparing the experimental
group to the control group found that there was a
13
significant difference between the means of the two groups
(t = 2.697, p = 0.016).
The mean GMS difference of the
experimental group was significantly higher (m = 0.0618, sd
= 0.02257) than the mean of the control group (m =
0.0057, sd = 0.01077).
-
This is displayed in Table 2 below.
Table 2: GMS difference between the Experimental and
Control Groups
N
Mean
Std. Dev.
Sig. (2(Nm/kg)
(Nm/kg)
tailed)
Training Group
Control
Hypothesis 2:
12
10
0.0618
-0.0557
0.02257
0.01077
p = 0.016
Females placed in the Trunk
Neuromuscular Training Program will significantly increase
their gluteus medius strength when compared to males. The
independent–samples t-test was calculated comparing the
mean scores of males in the experimental group and the mean
scores of females in the experimental group.
No
significant difference was found (t = -0.665, p = 0.527).
There was no significant difference between the mean GMS
difference of males (m = 0.0489, sd = 0.06312) to the mean
GMS difference of females (m = 0.0797, sd = 0.10072) in the
experimental group as can be seen in Table 3.
14
Table 3: GMS difference between Males and Females in the
Training Group
Gender in
N
Mean
Std. Dev.
Sig. (2Training
(Nm/kg)
(Nm/kg)
tailed)
Group
Males
7
0.0489
0.06312
p = 0.527
Females
5
0.0797
0.10072
Additional Findings
Dominant leg gluteus medius strength between the
experimental and control groups, non-dominant leg gluteus
medius strength between the experimental and control
groups, and the averages of the dominant leg and nondominant leg gluteus medius strength (GMS) between groups
were all analyzed for additional findings.
Dominant leg GMS comparing the experimental group to
the control group found that there was not a significant
difference between the means of the two groups (t = 1.786,
p = 0.098).
The mean GMS difference of the experimental
group (m = 0.0473, sd = 0.09376) was not significantly
different from the mean GMS difference of the control group
(m = -0.0029, sd = 0.02454) as can be seen in Table 4.
15
Table 4: Dominant leg GMS change between
the Training and Control Groups
N
Training
Group
Control
Mean
Std. Dev.
(Nm/kg)
(Nm/kg)
Sig. (2tailed)
12
0.0473
0.09376
p = 0.098
10
-0.0029
0.02454
Non-dominant leg GMS comparing the experimental group
to the control group found that there was a significant
difference between the means of the two groups (t = 2.649,
p = 0.015).
The mean GMS differences of the experimental
group (m = 0.0762, sd = 0.08523) was significantly
different from the mean of the control group (m = -0.0084,
sd = 0.05909) as can be seen in Table 5.
Table 5: Non-Dominant leg GMS change between the Training
and Control Groups
N
Mean
Std. Dev.
Sig. (2(Nm/kg)
(Nm/kg)
tailed)
Training
12
0.0762
0.08523
p = 0.015
Group
Control
10
-0.0084
0.05909
A paired-samples t-test was performed to determine if
there was a significant difference between gluteus medius
strength of the dominant and non-dominant legs in the
experimental group after six weeks of training.
There was
no significant difference (t = -1.143, p = 0.277) in the
mean GMS of the dominant leg compared to non-dominant leg
16
in the experimental group.
The mean of the dominant leg
GMS differences was 0.0473 (sd = 0.09376), and the mean of
the non-dominant leg GMS difference was 0.0762 (sd =
0.08523) as can be seen in Table 6.
Table 6: GMS difference between Dominant and
Non-Dominant Legs in the Training Group
N
Mean
Std. Dev.
Dominant
Non-Dominant
12
12
(Nm/kg)
(Nm/kg)
0.0473
0.0762
0.09376
0.08523
Sig. (2tailed)
p = 0.0277
A one-way ANOVA was performed comparing the average
GMS of the experimental group and the amount of days missed
(0,1,or 2).
No significant difference was found (F (2,9) =
2.507, p = 0.136).
The mean GMS difference for days missed
were 0 = 0.0968 ± 0.02496, 1 = 0.1032 ± 0.12078, and 2 =
0.0089 ± 0.02465 as can be seen in Table 7.
Table 7: Average GMS Difference Compared to Days Missed
Days
N
Mean
Std. Dev.
Sig. (2Missed
(Nm/kg)
(Nm/kg)
tailed)
0
4
0.0968
0.02496
p = 0.136
1
3
0.1032
0.12078
2
5
0.0089
0.05511
Total
12
0.07819
0.07819
17
DISCUSSION
The following is divided into three subsections:
Discussion of Results, Conclusion, and Recommendations.
Discussion of Results
The high rate of non-contact anterior cruciate
ligament injuries, specifically in females, has caused a
surge of research on preventative measures as well as NCACL
injury prevention programs.1,22-25
Injury epidemiology
research suggests that the hip and surrounding musculature
may play an important role in the poor biomechanics
associated with increased injury risk.1
The gluteal muscles
are the primary hip stabilizers, with the gluteus medius
being the primary hip abductors and lateral stabilizers.
The role of the gluteus medius and hip stabilizers in NCACL
injuries has lead to the inclusion of exercises in
prevention programs to improve strength and balance of
these muscles.9-14,22-25
The higher NCACL injury incidence
rate in females coupled with the decrease in gluteus medius
strength in females compared to males supports the theory
of the gluteus medius as a major component in the
18
prevention of NCACL injuries.4-7,9-14
An exhaustive search of
the literature did not yield any published studies that
have tested an ACL injury prevention program’s effect on
gluteus medius strength.
This study was performed to
provide data exploring potential strength changes in hip
musculature strength with the use of an ACL injury
prevention program.
The lack of research studying the change in hip
abductor strength following the implementation of an ACL
injury prevention program inspired this study incorporating
a six week implementation of the Trunk Neuromuscular
Training Program (TNT) and comparing the results of hip
abductor strength differences to a control group.
The
paucity of research in this area leads to little comparable
data for the first hypothesis that those in the training
group would significantly increase their gluteus medius
strength compared to those in the control group after the
TNT Program implementation.
Two studies, one by Chimera et
al and the other by Hewett et al, investigated hip abductor
musculature following a training protocol, however these
studies did not include strength measures.28,29
Chimera et
al noted a significant change in adductor to abductor
muscle co-activation during a vertical jump after the
implementation of a six week training protocol.28
19
Similarly, Hewett et al found a decrease in varus and
valgus movements following training and suggested the
results showed an increase in dynamic support of the hip
joint.29
protocol.
Each study utilized a plyometric based training
Plyometric training is the basis for the Trunk
Neuromuscular Training Program used in this study.
With
the observations of hip musculature change in these studies
we theorize that they support our findings of a significant
change, a 4.4% increase in average gluteus medius strength,
can be observed after the implementation of the Trunk
Neuromuscular Training Program after six weeks.
As previously stated, females suffer from a two to six
times higher incidence rate of NCACL injuries compared to
their male contemporaries.1,4-7 Several studies have also
shown that females differ significantly in hip abductor
strength and muscle activation patterns compared to males
of similar age.9-14
A large emphasis has been placed on
female NCACL injury research in previous years, which
explains why many programs that are currently available
employ language suggesting they are for female use.1,22-25
The Trunk Neuromuscular Training Program (TNT), designed by
Myer et al, is a prevention program that utilizes genderspecific language.24
This suggests, but does not confirm,
that it is intended by the authors for female use.
The
20
differences experienced by males and females during high
risk situations that may lead to a NCACL injury are well
documented.
The lack of research testing ACL injury
prevention programs extends into the realm of gender
differences experienced during the execution of a
prevention protocol.
To investigate our second hypothesis,
that females in the training group will increase their
gluteus medius strength significantly more compared to
males, we compared the gluteus medius strength differences
of the males in the experimental group to the females in
the experimental group.
The lack of a significant
difference suggests that the TNT program significantly and
equally strengthens the gluteus medius in both males and
females.
These results show an impartial change in GMS
despite noted anatomical, biomechanical, and hormonal
differences between males and females in relation to
anterior cruciate ligament injuries.2-4
These findings also
suggest that, despite females on average having a decrease
in GMS compared to males along with altered muscle
activation patterns according to Cowley et al, they do not
have strength increases that differentiate for the strength
gains seen in males.9-14
Further analysis of data used for the first hypothesis
was performed during additional findings.
These results
21
showed there was not a significant difference in dominant
leg GMS change in the experimental group, only 3.3%
increase, when compared to the control group, -0.4%.
This
is in contrast to the significant GMS difference
experienced by the non-dominant leg in the training group,
which was a 5.4% increase.
A comprehensive search of all
available research found only one study that examined hipabductor strength and leg dominance.
According to Jacobs
et al, the gluteus medius peak-torque is significantly
higher in the dominant leg compared to the non-dominant
leg.30
This may explain the lack of significant improvement
seen in the dominant leg gluteus medius when compared to
the non-dominant.
The majority of GMS was gained on the
non-dominant side which is, when compared to the results of
Jacobs et al, the weaker side.30 This could indicate that,
during this study, the progression of each phase in the TNT
program was dependent on the development of the nondominant leg gluteus medius strength.
While these findings
provide an intriguing theory, they remain in contrast to
the lack of significance between a comparison of GMS change
of the experimental group’s dominant and non-dominant legs.
A review of available literature indicates that many
studies focus on the dominant leg when collecting ACL
research.10,12,20,21
Using our results showing the non-
22
dominant leg gluteus medius receiving the majority of the
benefit, we can theorize that solely testing the dominant
leg could potentially skew the outcome of a research study.
Future research that would be of interest would use
parameters of a previous study that only tested the
dominant leg ACL and assess both legs.
The incorporation
of single leg as well as double leg exercises emphasizing
equal effort bilaterally are an important part of the Trunk
Neuromuscular Training program and has been cited by Myer
et al as an effective way of treating leg dominance.23,24
It
is for this reason that during the implementation of the
TNT program, the clinician needs to aware and attentive to
proper form so that the dominant leg is not overloaded,
potentially causing a neuromuscular pattern that could lead
to injury.
Statistics were also run to determine if the number of
training sessions missed altered the final dominant leg,
non-dominant leg, and average GMS scores of the subjects.
No published data was found to compare the number of
sessions missed in a protocol compared to reliability or
validity of the final results.
In an effective training
protocol, it is important to determine how many sessions
can be missed before strength gains begin to decrease as
compliance is usually not 100%.
For the purposes of this
23
study, the maximum number of sessions that the subjects
were able to miss was two.
Of the twelve subjects in the
experimental group four did not miss, three missed one day,
and five missed two days.
The results of the analysis
showed that there was not a significant difference between
the number of days missed and GMS in the experimental
group.
Despite the lack of significance, there was a
definite trend between those who missed zero or one day of
training compared to those who missed two days.
Those who
missed two days of training had a GMS score of .0943
Newtons, or about .924 kg of force, less than those who
missed either one or zero days of training. This may
suggest that future research should analyze similar
variables and exclude participants that miss multiple
sessions.
Conclusions
This study demonstrated that after a six week ACL
injury prevention program incorporating specific muscles
for the core and hip, there is a significant increase in
the average gluteus medius strength scores.
There was
significant difference in the average gluteus medius
strength scores between males and females in the
24
experimental group after the six weeks of training.
Additionally there was a lack of significance in the
difference of strength gains between the dominant leg
gluteus medius strength scores and the non-dominant leg
gluteus medius strength scores.
Finally, there was a lack
of significance in the post-test average, dominant and nondominant gluteus medius strength scores when compared to
the minimum and maximum amount of days missed, though there
was a definite drop-off trend noticed.
Our findings of higher strength gains in the nondominant leg as opposed to the dominant leg suggest that
weaker subjects may see a maximal benefit from the use of
this program seeing as the weaker side, non-dominant, saw a
larger increase in GMS.
The strength gains seen in males
and females imply that this program is significantly
effective for both genders as well as a variety of levels
of gluteus medius strength.
While gluteus medius strength
concerns only account for a small portion of the risk
factors associated with non-contact ACL injuries, the
widespread implementation of this program could potentially
decrease the number of injuries seen in relation to this
injury.
25
Recommendations
There is a lack of research investigating muscle
strength gains from ACL injury prevention programs.1
It is
extremely important to identify the most successful program
and the time frame in which the use of these programs can
provide the maximum amount of benefits between males and
females.
Our findings from this study, while not
staggering, show the benefits gained from the
implementation of a particular ACL injury prevention
program over a six week, 12 session period.
Larger numbers
studied may confirm the findings of our experiment.
The
next step would be to identify the minimal amount of time
needed to see meaningful benefits from the use of this
program.
Additionally, it would be interesting to study at
what point the benefits begin to plateau and the
introduction of a change in the program is needed.
Lastly,
testing of all muscles used in the prevention of noncontact ACL injuries, such as the quadriceps, hamstrings,
and abdominals, would further add legitimacy to the
prevention programs.
There was no significant difference noted between the
GMS scores of the males and females.
Muscle activation
patterns remain a significant theory in the cause of a
26
higher incidence rate of non-contact ACL injuries in
females.
For this reason it would behoove future
researchers to measure not only strength gains, but EMG
muscle firing patterns as well.
27
REFERENCES
1.
Hewett TE, Shultz SJ, Griffin LY, eds. Understanding
and Preventing Noncontact ACL injuries/American
Orthopaedic Society Sports medicine. 1st ed.
Champaign, IL: Human Kinetics; 2007.
2.
Shimokochi Y, Shultz S. Mechanisms of noncontact
anterior cruciate ligament injury. J Athl Training .
July 2008;43(4):396-408.
3.
Brindle T, Mattacola C, McCrory J. Electromyographic
changes in the gluteus medius during stair ascent and
descent in subjects with anterior knee pain. Knee Surg
Sport Tr A. July 2003;11(4):244-251.
4.
Uhorchak J, Scoville C, Williams G, Arciero R, St.
Pierre P, Taylor D. Riskfactors associated with noncontact injury of the anterior cruciate ligament: A
prospective four-year evaluation of 859 West Point
cadets. Am J Sport Med 2003; 31(6): 831-842.
5.
Arendt EA, Agel J, Dick R. Anterior cruciate ligament
injury patterns among collegiate men and women. J Athl
Training. 1999;34:86-92.
6.
Arendt E, Agel J, Dick R. Knee injury patterns among
men and women in collegiate basketball and soccer.
NCAA data and review of literature. J Athl Training.
June 1999;34(2):86-92.
7.
Arendt E, Dick R. Knee injury patterns among men and
women in collegiate basketball and soccer: NCAA data
and review of literature. Am J Sports Med.
1995;23:694-701.
8.
McKeon J, Hertel J. Sex differences and representative
values for 6 lower extremity alignment measures. J
Athl Training. May 2009;44(3):249-255.
9.
Russell K, Palmieri R, Zinder S, Ingersoll C. Sex
differences in valgus knee angle during a single-leg
drop jump. J Athl Training. April 2006;41(2):166-171
10.
Garrison J, Hart J, Palmieri R, Kerrigan D, Ingersoll
C. Comparison of knee-joint moments in male and female
28
college soccer players during a single-leg landing.
J Sport Rehabil. November 2005;14(4):332.
11.
Hughes G, Watkins J, Owen N. Gender differences in
lower limb frontal plane kinematics during landing.
ISBS. September 2008;7(3):333-341.
12.
Jacobs C, Uhl T, Mattacola C, Shapiro R, Rayens W. Hip
abductor function and lower extremity landing
kinematics: sex differences. J Athl Training. January
2007;42(1):76-83.
13.
Cowley H, Ford K, Myer G, Kernozek T, Hewett T.
Differences in neuromuscular strategies between
landing and cutting tasks in female basketball and
soccer athletes. J Athl Training. January
2006;41(1):67-73.
14.
Ford K, Myer G, Toms H, Hewett T. Gender differences
in the kinematics of unanticipated cutting in young
athletes. Med Sci Sport Exer. August 2005;37:129-9.
15.
Hewett T, Ford K, Myer G, Wanstrath K, Scheper M.
Gender differences in hip adduction motion and torque
during a single-leg agility maneuver. J Orthopaed Res.
March 2006;24:416-421.
16.
Liu X, Tingle T, Lintner D, Lowe W, Zhai Q, Luo Z.
Difference in collagen gene expression in male and
female anterior cruciate ligament injured athletes.
Biol Sport. 2009;26(3):255-261.
17.
Eiling E, Bryant A, Petersen W, Murphy A, Hohmann E.
Effects of menstrual-cycle hormone fluctuations on
musculotendinous stiffness and knee joint laxity. Knee
Surg Sport Tr A. February 2007;15(2):126-132.
18.
Hertel J, Williams N, Olmsted-Kramer L, Leidy H,
Putukian M. Neuromuscular performance and knee laxity
do not change across the menstrual cycle in female
athletes. Knee Surg Sport Tr A. September
2006;14(9):817-822.
19.
Hart J, Garrison J, Kerrigan D, Palmieri-Smith R,
Ingersoll C. Gender Differences in Gluteus Medius
Muscle Activity Exist in Soccer Players Performing a
29
Forward Jump. Res Sports med. April 2007;15(2):147155.
20.
Hanson A, Padua D, Blackburn J, Prentice W, Hirth C.
Muscle activation during side-step cutting maneuvers
in male and female soccer athletes. J Athl Training.
March 2008;43(2):133-143.
21.
Brindle T, Mattacola C, McCrory J. Electromyographic
changes in the gluteus medius during stair ascent and
descent in subjects with anterior knee pain. Knee Surg
Sport Tr A. July 2003;11(4):244-251.
22.
Filipa A, Byrnes R, Paterno MV, Myer GD, Hewett TE.
Neuromuscular training improves performance on the
star excursion balance test in young female athletes.
J Orthop Sport Phys. September 2010;40(9):551-8.
23.
Myer G, Chu D, Brent J, Hewett T. Trunk and hip
control neuromuscular training for the prevention of
knee joint injury. Clin Sport Med. 2008;27(3):425448.
24.
Myer G, Ford K, Hewett T. Rationale and clinical
techniques for anterior cruciate ligament injury
prevention among female athletes. J Athl Training.
October 2004;39(4):352-364.
25.
Myer G, Ford K, Brent J, Hewett T. Differential
neuromuscular training effects on ACL injury risk
factors in “high-risk” versus “low-risk” athletes. BMC
Musculoskelet Disord. May 2007;39(8):1-7.
26.
Hollman JH, Kolbeck KE, Hitchcock JL, Koverman JW,
Krause DA. Correlations between hip strength and
static foot and knee posture. J Sport Rehabil.
2006;15:12-23.
27.
The Lafayette Manual Muscle Test System user’s manual.
Lafayette, IN: Lafayette Instrument. 2003.
28.
Chimera NJ,
training on
performance
2004;39(1):
Swanik KA, et al. Effects of plyometric
muscle-activation strategies and
in female athletes. J Athl Training.
24-31.
30
29.
Hewett TE, Stroupe AL, Nance TA, Noyes FR. Plyometric
training in female athletes. Decreased impact forces
and increased hamstring torques. Am J Sports Med.
1996; 24(6): 765-773.
30.
Jacobs C, Uhl TL, Seeley M, Sterling W, Goodrich L.
Strength and fatigability of the dominant and
nondominant hip abductors. J Athl Training. July
2005; 40(3): 203-206.
31
APPENDICES
32
APPENDIX A
Review of Literature
33
REVIEW OF LITERATURE
The purpose of this literature review is to discuss
the gluteus medius and its relationship to non-contact
anterior cruciate ligament (NCACL) injuries and ACL injury
prevention programs. Anterior cruciate ligament injuries
are one of the most prevalent injuries in athletics. It has
been suggested that 75,000 to 250,000 ACL tears occur in
the United States each year.1 Unfortunately, for female
athletes, they suffer a four to six time higher incidence
rate for non-contact ACL injuries compared to male athletes
of a similar age.1
While current research has brought us
closer to understanding this discrepancy, there remain
uncertainties to this complicated issue.
Several factors
for the increase in injury among females have been
suggested.
These factors include anatomical, hormonal,
biomechanical, and neuromuscular differences between
genders.1,2
Regardless of gender, it is important to
implement injury prevention programs that focus on reducing
the occurrence of anterior cruciate ligament injuries.
The gluteus medius plays a key role in the prevention
of patellofemoral injuries.3 The strengthening of this
muscle should be included in any preventative ACL injury
program.
Not all prevention programs include the same
34
components, so it is extremely important to understand the
components and the effectiveness of these programs.
This
literature review will outline the importance of the
gluteus medius in ACL injury prevention by discussing what
a noncontact ACL injury is, the anatomy involved including
the functional anatomy, the role of the gluteus medius, and
specific gender differences as well as mechanical
alterations and current ACL prevention programs and their
components.
Noncontact ACL Injuries
For an ACL injury to be considered noncontact, there
needs to be an absence of outside contact with the knee
during the time of injury.
While the exact etiology of
noncontact anterior cruciate ligament injuries remains
unknown,1 recent research has aided in our understanding of
risk factors.
A study by Griffin et al defined
environment, anatomy, hormonal, and biomechanics as the
four typical risk factors for ACL injuries.4 These factors
will be discussed in later sections in more detail.
Situations that can create a force necessary for a
noncontact ACL injury include, but are not limited to,
landing from a jump, sudden changes in direction, and
35
deceleration.1 Most noncontact anterior cruciate ligament
injuries tend to happen in the closed kinetic chain. When
the body is in direct contact with the physical
environment, it can create a model situation for injury.
For example, during a drop jump landing, an increase in
knee valgus force coupled with internal rotation of the
femur creates a common mechanism of injury.1 The increase
in internal rotation of the femur can be due to a weakness
in hip external rotators, including the gluteus medius.
Muscular weakness is also a major contributor to
noncontact ACL injury. A lack of co-contraction of the
hamstrings during quadriceps contraction can create the
shear forces necessary to cause an anterior cruciate
ligament injury when the knee is at or near full extension.
Understanding of the definition of noncontact ACL injuries
is important when trying to determine the incidence of
these injuries in sports.
Incidence
The incidence of noncontact anterior cruciate ligament
injuries has been estimated at approximately 70% of all ACL
injuries.1,4
Prevalence and incidence are two separate
concepts that are, unfortunately, commonly misused and
misunderstood.
Incidence is the rate in which something
36
occurs within a population.
Incidence as it pertains to
ACL injury research is done in a prospective manner
studying the number of injuries sustained in a group of
subjects during a predetermined amount of time.
It is
difficult, if not impossible, to determine the number of
anterior cruciate ligament injuries within the general
population.
Even with the National Ambulatory Care
Surveys, all cruciate ligament injuries are reported under
the same ICD code, creating mixed numbers.
Even if it were
possible to differentiate between the injuries in this
situation, the survey covers total visits for ACL injuries,
which could be an indeterminable number per patient.1
With
these limitations aside, incidence rates have been
determined in smaller populations.
There have been many
studies that focus on anterior cruciate ligament injury
within specific athletic populations.
A study done by Uhorcak et. al. analyzed 859 West
Point Cadets over four years to better understand the
incidence and risk factors that are present in an athletic
population.5
While military men and woman are not
considered athletes, their training and conditioning are
certainly athletic in nature, therefore allowing for
comparisons.
All 859 cadets were assessed by physical
examination, strength assessment, and exposure data.
Of
37
the 859 cadets there were 29 anterior cruciate ligament
injuries over the four year study.
were considered noncontact.
Twenty four of these
This is an incidence rate of
approximately 3.4% in the general population and an 82.7%
noncontact injury rate, which is significantly higher than
the previously noted 70%.
The benefit of this study is
that it incorporates males and females as well as clearly
defining noncontact ACL injuries.
The differentiation of
male and female subjects is important because it shows the
large discrepancy between the genders.
The incidence rate
for females was found to be 6.6% while it was only 2.1% in
males.
The authors cite specific anatomical and
physiological reasons that are to be discussed later in
this review.
The National Collegiate Athletic Association Injury
Surveillance System (ISS) was developed in 1982 to provide
the most up to date and reliable data on injury trends.
This has been an invaluable tool for researchers trying to
identify injury discrepancies between sports, gender, and
collegiate division.
A study done by Agel et al6 used the
ISS to follow noncontact ACL injuries between males and
females participating in basketball and soccer. This study
was built upon previous results,7,8 giving an extensive look
into ACL injury patterns.
When the researchers compared
38
noncontact ACL injuries between genders, the results were
mostly similar to previous studies.
Male basketball
players suffered a 70.1% rate of noncontact ACL injuries
compared to contact while female basketball players
suffered a 75.7% rate.
Males suffered 37 contact and 78
noncontact injuries, while females suffered 100 contact and
305 noncontact ACL injuries.
Though this was not
considered a significant difference from previous results,
the results from soccer showed a note worthy change.
Male
soccer players suffered a 49.6% rate of noncontact anterior
cruciate ligament injuries while the rate for females was
58.3%.
The 49.6% rate for males was considered a
significant decrease, which causes one to wonder as to the
reason for the change.
Further results from the study
showed that regardless of the sport, females had a much
higher incidence rate of anterior cruciate ligament injury.
While this information is extremely important in the
identification of the injury discrepancy, it does not mean
that ACL injuries in males should be ignored, especially
since there are more males experiencing NCACL injuries per
year than females.
39
Anatomy
It is extremely important to understand the anatomy
involved in anterior cruciate ligament injuries.
In order
to understand the possible etiologies of noncontact ACL
injuries, one must understand how stability is maintained
within the knee joint.
There are two joints within the
complex of the knee, the patellofemoral and tibiofemoral.
The patellofemoral joint is the articulation of the patella
and the femur, while the tibiofemoral joint is articulation
of the femur on the tibial plateau.
Additionally, there are two types of stabilizers in
the knee; passive and dynamic.
Passive stabilization is
provided by the joint capsule, the menisci, the anterior
cruciate ligament, the posterior cruciate ligament (PCL),
the lateral collateral ligament (LCL) and the medial
collateral ligament (MCL).
Dynamic stabilization is
provided by the muscles that cross the knee joint, which
are the quadriceps muscles and the hamstring group.9
Reference to how important the ACL is can be heard
nearly every time a star athlete sustains a knee injury,
but often times the general public lacks the understanding
of why it is so important.
The main functions of each of
the cruciate ligaments (ACL and PCL) are exact opposites.
40
The ACL attempts to impede anterior tibial translation on
the femur and the PCL attempts to stop a posterior shear
force of the tibia on the femur.
While this may seem
backwards, the ligaments receive their names from their
origins.
The ACL originates at the anterior intercondylar
area of the tibial plateau and inserts to the
posteriomedial part of the lateral femoral plateau.
Conversely, the PCL originates in the posterior aspect of
the intercondylar notch and inserts at the anterior
inferior lateral aspect of the medial femoral plateau.9
Anatomy Involved in ACL Injury
According to Griffin et al, there has not yet been a
reliable measure of any single anatomical variable that
increases the risk of anterior cruciate ligament injury.10
This does not, however, discount the fact that several
anatomical factors have been suggested as risk factors for
ACL injury.
These factors include femoral intercondylar
notch width, pelvic angle, quadriceps angle, and subtalar
pronation.1
Suggestions of intercondylar notch width’s
relationship to ACL injury are not a recent development,
and yet there is little empirical data that can give a
definitive answer.
Also, recent conflicting MRI studies
41
have increased the uncertainty.11,12
The exact correlation
between a decreased intercondylar notch width and ACL
injury has not been specified.
However, further findings
in the study done by Uhorchak et al.5 suggested that the
increase of ACL injury in those with a smaller
intercondylar notch width could be due to an abnormal
loading of the ACL as well as a smaller ACL, which would
lead to a decrease in the ultimate failure point of the
ligament.
Unlike intercondylar notch width, there is little
controversy surrounding the hypothesis of pelvic angle’s
effects on ACL injury.
It has been suggested that an
increase in anterior pelvic tilt can create a medial
collapse of the lower extremity, causing internal rotation
of the femur leading to genu valgus at the knee.
It has
also been noted that anterior pelvic tilt can create other
structural abnormalities such as genu recurvatum and
subtalar pronation.13
Dynamic stability is also compromised
due to a stretch weakness of the hamstrings.
The quadriceps angle, also known as the “Q” angle, is
a measurement formed by the alignment of the center of the
patella to the anterior superior iliac spine and the center
of patella to the tibial tuberosity.
It is well documented
that a Q angle greater than 20 degrees can lead to a
42
patellofemoral pathology.14 An increased quadriceps angle
can also lead to an increase in knee valgus and torsion
within the knee.1
Subtalar pronation is often overlooked in patients
with an ACL injury.
Pes planus is typically the cause of
subtalar pronation.
The excessive pronation that is
occurring at the joint creates an internal rotation of the
femur, leading to internal rotation at the knee.15
This
internal rotation at the knee places a stress on the ACL
and may contribute to a higher risk for injury.
This is a
condition that can easily be exaggerated by other
biomechanical issues, such as an internal rotation of the
femur, causing a larger medial collapse.
It is important to note that anterior cruciate
ligament injuries are typically a result of several
factors.
Though some of the mentioned studies focus on a
single reason, it does not indicate that other factors were
not present.
There are other factors that have been
suggested, but have little to no supporting evidence.
These factors include femur to tibia length, anteversion of
the hip, tibiofemoral angle and genu recurvatum.1
43
Role of Gluteus Medius
The primary function of the gluteus medius is to
abduct the hip and internally rotate the thigh.
It takes
its origin from the iliac crest and inserts on the greater
trochanter.16,17
The gluteus medius is also a pelvic
stabilizer, which is extremely important in preventing a
medial collapse and maintaining proper kinematics of the
lower extremity.18
A medial collapse is characterized by an
internal rotation of the femur, knee valgus, and subtalar
In a study performed by Brindle et al.3 gluteus
pronation.
medius weakness was found to be related to anterior knee
pain in subjects performing ascent and descent of stairs.
With this in mind, it only seems right to implement a
comprehensive strength training prevention program that
effectively targets the gluteus medius and surrounding
musculature.
Differences between Gender
Gender differences have been suggested in several
studies as a reason for the greater incidence of NCACL
injuries in females.19-32
This leads to the discussion of
several areas where key differences have been studied;
anatomical,19 knee valgus angle,20-25 femoral internal
44
rotation,26 hormonal differences,27-30 and muscle activation
patterns.31,32
Recent research has identified four typical anatomical
differences between males and females that may lead to
NCACL injuries.
Medina et al collected measurements from
118 males and females ranging from active adults to elite
athletes.19
Their findings showed that women demonstrate
larger quardriceps angles, more genu recurvatum, greater
anterior pelvic tilt and larger femoral anteversion when
compared to males.
The researchers suggest that the
structural differences can lead to biomechanical
alterations.19
Single leg landings are a functional test that
multiple studies use to test knee valgus angles.
Many
sports require athletes to jump, and this sudden
deceleration is a typical mechanism for anterior cruciate
ligament rupture.1
Studies done by Russell et al.,20
Garrison et al.,21 Hughes et al.,22 and Jacobs et al.23
implemented the use of a drop jump to measure valgus angles
in the knee between the genders.
Each study found that
females exhibited a greater valgus angle during their
landings when compared to males.
Two of the studies also
tested for differences between the genders’ hip abduction
upon landing.20,22
One study did not find a difference in
45
muscle activation strategy between males and females,20
while the other’s findings suggested that females
demonstrate a lower activation rate of hip abduction.22
Differences are not only seen between genders in the
case of knee valgus, but also between females participating
in different sports.
In a study done by Cowley et al24
between female basketball and soccer players it was found
that females typically demonstrated greater knee valgus
angles during sport specific tasks, such as jumping and
landing in basketball and cutting in soccer.
The results
of this study also discovered greater knee valgus moments
during cutting tasks compared to landing tasks among
females.
This supports the incorporation of sport specific
movements into NCACL injury prevention programs to
strengthen the appropriate musculature and possibly
decrease knee valgus angles.
Gender differences have been noted as early as twelve
years of age by Ford et al25. In their study, in which 54
male and 72 female athletes of adolescent age performing a
cutting maneuver, it was found that the females suffered
from not only greater knee valgus angles during the landing
and stance phases when compared to males, but also from a
higher maximum ankle eversion during the landing phase and
46
decreased inversion during the stance phase.
This suggests
that ACL injuries may be influenced by ankle kinematics.
Many studies tend to focus on knee valgus measurements
instead of potential causes for an increase in hip
adduction.
In a study by Hewett et al26 hip adduction
angles were measured in male and female athletes performing
a single leg, bidirectional deceleration maneuver.
Results
of this study showed that females suffer from a larger
angle of hip adduction during all phases of the maneuver.
An increase in hip adduction motion can predispose an
athlete to a functional medial collapse, creating a perfect
environment for NCACL injury.26
Another area of difference between genders involves
changes at the molecular and hormonal levels.
A difference
in collagen gene expressions between genders is a
relatively recent area of study in consideration of
anterior cruciate ligament injuries.27
There are primarily
two types of collagen in the ACL; type I collagen and type
III collagen.
Type I collagen makes up about 90% of the
ACL while type III makes up approximately 10%.25
Liu et al
harvested the ACLs of 17 male and 17 female athletes who
required ACL reconstruction and tested them using reverse
transcript-polymerase chain reaction to determine if a
difference in fibroblast collagen gene expression existed.
47
Their findings showed a significantly different lower
relative expression of collagen I in the females.
The
question remains as to why this is the case, but the
researchers do theorize that hormonal differences may be
the cause.27
A 2006 study by Eiling et al28 focused on the effects
of the menstrual cycle on musculotendinous stiffness as
well as knee laxity.
The tests were performed during each
phase of the menstrual cycle using a knee arthrometer.
The
measurements that were produced showed, on average, a 4.2%
decrease in musculotendinous stiffness during the ovulatory
phase.27
The decrease in musculotendinous stiffness can
lead to a reliance on noncontractile tissue to support a
joint.
In this case that would mean more forces acting on
the ACL in female athletes than male athletes.
This
evidence was supported in 2007 by a survey study that
viewed previous ACL injuries of females and the stage of
their menstrual cycle at the time of injury.
72% of the
subjects who had suffered a noncontact ACL injury did so
during the ovulatory phase.28
Suggestions of hormonal relations to non contact ACL
injuries in females are not, however, fully supported.
Both studies previously mentioned suffer from a limited
sample size.
While they both present an interesting look
48
into the possibilities of the subject, neither has been
validated and are, in fact, currently being challenged as
incorrect through a research study underway at Pennsylvania
State University using similar methods.29
A difference in muscle activation patterns between
genders has been suggested as a cause for the higher
incidence of NCACL injuries in females.24,30,31
A delayed or
limited activation of certain muscles during the landing
phase of a jump, like the gluteus medius, may lead to NCACL
injuries.
Similarly, if there is a delay or an over
compensation in muscle activation patterns during cutting
tasks there is a possibility for injury.
A study by Hart et al30 examined eight male and eight
female soccer players performing a single leg landing.
The
researchers collected surface electromyography data from
the gluteus medius, vastus lateralis, lateral hamstring,
and medial gastrocnemius during the jumps of each
participant.
Their results showed that the males had
significantly higher gluteus medius activity during the
landing when compared to the females.
Hanson et al32 recorded surface electromyographic
activity for the rectus femoris, vastus lateralis, medial
and lateral hamstrings, gluteus medius and gluteus maximus
during a running-approach side-step cut and a box-jump
49
side-step cut in twenty males and twenty females.
The
participants used in the study were NCAA division I
athletes.
Results from this study demonstrated that
females suffer from larger quadriceps activation as well as
a larger quadriceps to hamstring coactivation ratio.
The
greater activation of the quadriceps without the hamstrings
counter balancing them creates an anterior shear force
within the knee, placing stress directly on the ACL. These
findings are also significant in that they confirm that the
quadriceps to hamstrings coactivation ratio exists in
advanced athletes as well as recreational athletes.31
Mechanical Alterations
Structural alterations are not solely responsible for
the occurrence of ACL injuries.
Dynamic factors such as
fatigue can create a harmful situation for the athlete.
These mechanical alterations can lead to a loss of dynamic
stability, leaving the anterior cruciate ligament prone to
injury.
The relationship of muscle fatigue and ACL injury
has been previously suggested.32,33
Chappell et al.32 found
that knee kinetics are significantly affected when muscle
fatigue is introduced to three jump stop tasks.
The
results showed an increase in anterior tibial translation,
50
which can place an undesirable stress on the ACL, possibly
causing injury.
In a related study by Melnyk and
Gollhofer,33 fatigue in the hamstrings was found to cause an
increase in anterior tibial translation as well.
The
decrease in latency response of the hamstrings
significantly affected the muscles ability to stabilize the
knee joint.
Fatigue of hip abductors also presents a
Carcia et al34 outlined a study
problem to the athlete.
that created bilateral fatigue in the hip abductors of
their participants and then observed changes in their
landing characteristics during a drop jump.
The fatigue of
hip abductors was found to significantly increase knee
valgus, possibly leading to injury in the ACL.
Prevention Programs
After reading through the research on ACL injuries,
there is a quick realization that preventative measures
need to be taken to combat these injuries.
Different
techniques have been used and implemented to decrease the
incidences of ACL injury.
Recently there have been
significant gains in NCACL injury prevention programs
focusing on neuromuscular training programs that have been
shown to reduce the incidence of NCACL injuries.36-37
51
Components
Neuromuscular training programs focus on a decreased
risk of injury.
While not all programs are the same,
typically the more common components of successful programs
include technique training and plyometric training.
A
relatively new suggestion involving the implementation of
core exercises to increase stability and proprioception is
theorized to have an effect on lower extremity
kinematics.36-38
Previous Results
Seeing the need for prevention programs, many studies
have tested the effects of certain exercises on musculature
as well as prevention programs as a whole.
It is important
to identify which muscles need to be strengthened.
Many
studies identify gluteus medius weakness as a
predisposition to injury.3-5,16-18,22,25,30,34
Though the gluteus
medius is an important muscle, it is certainly not the only
muscle of interest concerning ACL injury prevention.
The
sheer amount of literature on the subject proves that there
is no single answer to this complicated problem.
In
order to understand where ACL prevention programs are
52
going, it is necessary to understand the related
literature.
McCurdy et al tested the electromyography activity in
specific muscle groups of the hip and knee during a single
leg squat as well as a two legged squat.40
Eleven female
athletes were tested during three repetitions at 85% of
each athlete’s one repetition maximum.
The results from
the study show that single leg squats produce a higher mean
peak activity in the gluteus medius and hamstrings while a
two legged squat’s activity levels are higher in the
quadriceps.
These results suggest that when training to
target the gluteus medius muscle, single leg squats are
more effective than two legged squats.40
The study’s focus
on females prevents a complete translation in similarity to
males, but it does allow for some speculation.
In a study done by Boudreau et al, muscle activation
patterns of the rectus femoris, gluteus maximus, and
gluteus medius were measured in 44 healthy individuals
while performing three trials of lunges, single leg squats,
and step up and overs.
The results found that lunges were
the best choice of the three exercises for gluteus medius
activation.41
Although the study was performed using an
equal number of men and women, the study mentions no
differences between the genders in the levels of muscle
53
activation for each exercise.
These results clearly show
that lunges can be potentially one of the best exercises
when attempting to strengthen hip abductors.
Further studies outline marked improvements in
neuromuscular training’s effects on noncontact ACL injury
prevention.42-45
It is interesting though, that there has
been an abundance of research on the different effects of
NCACL injury prevention training, but there has not yet
been a clear decrease in the occurrence of this injury.6,46
Use of Prevention Programs
Before a prevention program is fully implemented,
Hewett et al suggests that the participant is evaluated
through a series of jump tasks to identify ligament
dominance, quadriceps dominance, and leg dominance.47
These
are three neuromuscular risk factors that are easily
identifiable and can be corrected during the execution of
the program.
With ligament dominance there is an imbalance
of neuromuscular control, leading to a reliance on the
ligament for the majority of support.48
This is typically
characterized by a lack of control of knee valgus during
jumping and cutting and should be identified by watching
the subject perform a maximal vertical jump.46
Quadriceps
dominance is presented as an unproportionate increase in
54
the quadriceps to hamstring ratio, with the quadriceps
muscle overpowering the hamstrings.49
This creates a
shearing force within the knee, placing stress on the ACL.
Dominance of the quadriceps can be determined easily
through the use of leg curl and leg extension machines.
If
the subject has a hamstring to quadriceps ratio of less
than 55% they may be considered to suffer from quadriceps
dominance.47
Leg dominance is defined as a lack of
strength, coordination and balance before the lower limbs
by Myer et al.47
There are several different ways to test
for leg dominance.
The first method is to measure strength
and determine if one limb can exceed the other by 20% or
more.
The second method consists of a balance test to
observe postural sway.
The final measurement of leg
dominance is the use of a four quadrant exercise.
In this
exercise the subject stands on a single limb and hops
across and diagonal into the corresponding quadrants,
holding each position for three seconds.
The subject’s
ability to maintain stability is the sole measure for this
exercise.47
It is extremely important to attempt to
eliminate the risk of injury during the implementation of
prevention programs because subjects may sometimes be
placed in positions their bodies are unfamiliar with.
55
Summary
The current estimations of 75,000 to 250,000 ACL
injuries a year create a need for the implementation of
NCACL prevention programs to reduce the incidence of this
injury.
Of these 75,000 to 250,000 ACL injuries, it has
been suggested that 70% of them are considered noncontact.1
The gluteus medius muscle has been identified as an
important component of noncontact ACL injuries.
It is
considered important due to its primary function, which is
to abduct the hip and internally rotate the thigh.16,17
The
strengthening of the gluteus medius muscle may help in the
prevention of a functional medial collapse, which could
lead to damaging the ACL.3
There is currently a large
amount of research focusing on female athletes and a higher
incidence of injury compared to males.
Regardless of which
gender is more at risk, it is important to identify
strength training programs that can aid in the reduction of
ACL injuries.
Current programs in use need to be tested to
observe their effectiveness in related musculature as well
as their value between genders.
56
APPENDIX B
The Problem
57
Statement of the Problem
The purpose of the study is to examine the effect of
an ACL injury prevention program on gluteus medius strength
between males and females.
It is important to examine this
relationship because current research shows a direct
relationship between the strength of the gluteus medius and
ACL injuries.
Strengthening the gluteus medius may aid in
the reduction of stressors in the lower extremity due to
joint malalignment.
It is also important to determine if
males and females benefit similarly to determine if there
is a need for more or less gender specific ACL injury
prevention programs.
The knowledge gained from this study
may be beneficial to those looking to prevent ACL injuries.
We do not know if there will be significant gains in
gluteus medius strength through the use of the Trunk
Neuromuscular Training Program, and we also do not know if
there will be a difference in the benefits gained between
the genders.
Definition of Terms
The following definitions of terms will be defined for
this study:
1)
ACL Prevention Program – A program that is designed to
prevent an injury of the anterior cruciate ligament
58
through the use of neuromuscular and proprioceptive
training techniques.
2)
Physically active college aged students – Study
participant that engages in physical activity for at
least 30 minutes three times a week and are aged
between 18 and 26.
3)
Lafayette Manual Muscle Test System (MMTS) – a device
used to objectively measure muscle strength.
Basic Assumptions
The following are basic assumptions of this study:
1)
All subjects will follow the exercise protocol they
have been assigned.
2)
The subjects will put forth a maximal effort during
their exercise sessions and during strength testing.
3)
The subjects will be honest in their completion of the
demographic forms.
4)
All testing instruments are valid and reliable tools
that are used for their intended purpose.
5)
Subjects for the study are volunteers who were not
coerced in any way to participate.
Limitations of the Study
The following are possible limitations of the study:
59
1)
The number of participants involved in this study may
not be large enough for significant results.
2)
Findings are limited to active, college-aged
recreational student athletes.
3)
The six week time limit for the implementation of the
exercises programs may not be long enough for
significant results to be achieved.
Significance of the Study
Anterior cruciate ligament injuries are among the most
devastating injuries that can be sustained by athletes.
Currently, it is estimated that between 75,000 and 250,000
ACL injuries occur each year.
The gluteus medius muscle
provides an important role in preventing lower extremity
injuries through stabilization of the pelvis.
The
stabilization of the pelvis contributes to preventing a
valgus collapse of the knee, which is characterized by
internal rotation of the femur, knee valgus, and ankle
pronation.
There are several ACL injury prevention
programs that are currently available to the public.
This
study uses an ACL injury prevention program to test it’s
effects on the gluteus medius muscle between males and
females.
Current research indicates a higher incidence of
ACL injuries in the female population when compared to
60
males.
For this reason, many prevention programs have been
tailored to the female population.
It is crucial to
determine if males and females both benefit similarly from
currently available ACL injury prevention programs.
The
information gained from this study may provide future
researchers with an understanding of what programs provide
the best results.
The information gained from this study
may also show that there may be a need for more or less
gender specific ACL injury prevention programs.
61
APPENDIX C
Additional Methods
62
APPENDIX C1
Informed Consent Form
63
Informed Consent Form
1. Jordan Blair, who is a Graduate Athletic Training Student at California University of
Pennsylvania, has requested my participation in a research study at California University
of Pennsylvania. The title of the research is The Effect of an ACL Injury Prevention
Program on Gluteus Medius strength between Genders
2. I have been informed that the purpose of this study is to examine the effect of an ACL
injury prevention program on gluteus medius strength between males and females. I
understand that I must be 18 years of age or older to participate. I understand that I have
been asked to participate along with 31 other individuals because I am physically active,
as defined as participating in moderate to intense exercise at least 3 times a week
3. I have been invited to participate in this research project. My participation is voluntary
and I can choose to discontinue my participation at any time without penalty or loss of
benefits. My participation will involve pre and post testing to occur before and after the
implementation of either the Trunk Neuromuscular Training (TNT) program over six
weeks or no exercise assignment over six weeks. I acknowledge that the TNT program
will involve an exercise session to meet two times a week taking approximately 25
minutes to complete including the exercises associated with the program as well as a
warm up. I also acknowledge that these exercises will be demonstrated to me on the first
day of my exercise program.
4. I understand there are foreseeable risks or discomforts to me if I agree to participate in
the study. With participation in a research program such as this there is always the
potential for unforeseeable risks as well. I understand that the risks I may be exposed to
include, but are not limited to, soreness associated with exercise as well as injuries that
may be sustained during normal bouts of physical activity that involve the lower
extremity.
5. I understand that, in case of injury, I can expect to receive treatment or care in Hamer
Hall’s Athletic Training Facility. This treatment will be provided by the researcher,
Jordan Blair, under the supervision of the CalU athletic training faculty, all of which can
administer emergency care. Additional services needed for prolonged care will be
referred to the attending staff at the Downey Garofola Health Services located on
campus.
6. There are no feasible alternative procedures available for this study.
7. I understand that the possible benefits of my participation in the research is to
contribute to existing research and may aid in the enhancement of ACL injury prevention
programs.
64
8. I understand that the results of the research study may be published but my name or
identity will not be revealed. Only aggregate data will be reported. In order to maintain
confidentially of my records, Jordan Blair will maintain all documents in a secure
location on campus and password protect all electronic files so that only the student
researcher and research advisor can access the data. Each subject will be given a specific
subject number to represent his or her name so as to protect the anonymity of each
subject.
9. I have been informed that I will not be compensated for my participation.
10. I have been informed that any questions I have concerning the research study or my
participation in it, before or after my consent, will be answered by:
Jordan Blair, ATC
STUDENT/PRIMARY RESEARCHER
Bla5790@calu.edu
412-477-5657
Shelly DiCesaro, PhD, ATC, CSCS
RESEARCH ADVISOR
Dicesaro@calu.edu
724-938-5831
11. I understand that written responses may be used in quotations for publication but my
identity will remain anonymous.
12. I have read the above information and am electing to participate in this study. The
nature, demands, risks, and benefits of the project have been explained to me. I
knowingly assume the risks involved, and understand that I may withdraw my consent
and discontinue participation at any time without penalty or loss of benefit to myself. In
signing this consent form, I am not waiving any legal claims, rights, or remedies. A copy
of this consent form will be given to me upon request.
13. This study has been approved by the California University of Pennsylvania
Institutional Review Board.
14. The IRB approval dates for this project are from: 02/24/11 to 02/23/12.
Subject's signature:___________________________________
Date:____________________
Witness signature:___________________________________
Date:____________________
65
APPENDIX C2
Institutional Review Board –
California University of Pennsylvania
66
Proposal Number
Date Received
PROTOCOL for Research
Involving Human Subjects
Institutional Review Board (IRB) approval is required before
beginning any research and/or data collection involving human subjects
(Reference IRB Policies and Procedures for clarification)
Project Title The Effect an ACL Injury Prevention Program on Gluteus Medius Strength Between Genders
Researcher/Project Director
Jordan Blair
Phone # 412-477-5657
E-mail Address BLA5790@calu.edu
Faculty Sponsor (if required) Dr. Shelly Dicesaro
Department Health Science
Project Dates January 2011 to June 2011
Sponsoring Agent (if applicable)
Project to be Conducted at California University of Pennsylvania
Project Purpose:
Thesis
Research
Class Project
Keep a copy of this form for your records.
Other
67
Please attach a typed, detailed summary of your project AND complete items 2
through 6.
1. Provide an overview of your project-proposal describing what you plan to do and how you
will go about doing it. Include any hypothesis(ses)or research questions that might be
involved and explain how the information you gather will be analyzed. For a complete list of
what should be included in your summary, please refer to Appendix B of the IRB Policies and
Procedures Manual.
The purpose of this study is to examine the effects of an ACL injury prevention program on
gluteus medius strength between males and females. Physically active students, ages 18 to
26, from California University of Pennsylvania are expected to participate in this study
(N~32). Subjects that are currently suffering or recovering from a lower extremity injury
sustain within the past 6 months will not be included in this study. The subjects who sign the
informed consent will be randomly assigned into two separate groups (N~16) consisting of
equal numbers of males (N~8) and females (N~8). One group will be the experimental group
that will be given the pre test, prevention program, and post-test, while the other group will
be the control that will only receive the pre-test and post-test. Gluteus medius strength will
be measured before and after the implementation of the ACL injury prevention program,
using the hand held Lafayette Manual Muscle Test System (MMTS), which is a small handheld device that is placed over top of the muscle during a contraction to provide an objective
measure of muscle strength. Testing will be done on both legs. For the muscle test, the
subjects will lay on the opposite side that is being tested and the MMTS will be placed over
the gluteus medius, which is located on the side of their hip. The subjects will then gradually
push as hard as they can against the MMTS which will be in the researcher’s hand. The pretest measurement will provide a baseline from which to observe the effect of the program on
gluteus medius compared to the control group. Demonstrations of each exercise will be done
the first day of subject’s participation to familiarize the subjects with the exercises. The
researcher will also be available during the scheduled time for the subjects exercise sessions.
Exercise sessions will be formulated based on the schedules of the subjects as well as the
researcher. A log book will be kept to ensure attendance of the subjects. If any subject
misses more than two scheduled exercises sessions or two sessions in a row they will be
excluded from the study. Pictures and descriptions of all exercises from the program are
attached. The following hypotheses will be investigated during this study; the trunk
neuromuscular training program will significantly increase gluteus medius strength when
compared to the control group. All data that is collected will be analyzed by SPSS for
windows version 17.0 at an alpha level of .05 using a two way ANOVA.
2. Section 46.11 of the Federal Regulations state that research proposals involving human
subjects must satisfy certain requirements before the IRB can grant approval. You should
describe in detail how the following requirements will be satisfied. Be sure to address each
area separately.
a. How will you insure that any risks to subjects are minimized? If there are potential
risks, describe what will be done to minimize these risks. If there are risks, describe
why the risks to participants are reasonable in relation to the anticipated benefits.
The potential risks involved will be outlined in the Informed Consent form and
include delayed onset muscle soreness (DOMS), which is general muscle soreness
and a common side effect of exercise, that may last two to three days. Other risks
involve injuries that could be sustained during a normal exercise program involving
68
the lower extremity including minor strains and sprains. Any injuries sustained
during testing will be treated by the researcher or the researcher's advisor, both
certified athletic trainers. To minimize the risk of injury, each group of subjects will
be instructed on how to properly warm up and these warm ups will be incorporated
into the ACL injury prevention program. Every exercise will be demonstrated, by the
researcher, to the participants prior to the subjects beginning the exercise. Also, the
researcher or an undergraduate athletic training student, who is certified in first aid
and CPR, will be present for each exercise session to ensure proper form for each
exercise is being implemented to reduce the risk of injury.
b. How will you insure that the selection of subjects is equitable? Take into account
your purpose(s). Be sure you address research problems involving vulnerable
populations such as children, prisoners, pregnant women, mentally disabled persons,
and economically or educationally disadvantaged persons. If this is an in-class
project describe how you will minimize the possibility that students will feel coerced.
The selection of subjects will be done on a volunteer basis. Only students deemed
physically active will be included in the study. Subjects are considered physically
active if they exercise for at least 30 minutes 3 or more times a week. Subjects
recruited for the study will be students in health science classes at California
University of Pennsylvania. Announcements of ability to participate in the study will
be made in health science classes as well as through E-mail. To avoid the feeling of
coercion, students will be assured that they are not required to participate and should
only do so if they desire.
c. How will you obtain informed consent from each participant or the subject’s legally
authorized representative and ensure that all consent forms are appropriately
documented? Be sure to attach a copy of your consent form to the project summary.
An informed consent form, that the students will have ample time to read, will be
signed and completed by the subjects during a meeting to take place before the
implementation of the exercise program. Before the informed consent form is
signed, participants will have ample time to ask any questions they may have. A
copy of the form is attached.
d. Show that the research plan makes provisions to monitor the data collected to insure
the safety of all subjects. This includes the privacy of subjects’ responses and
provisions for maintaining the security and confidentiality of the data.
All data will be collected by the researcher and placed in a secure cabinet known only
to the researcher and research advisor. A key to the cabinet will be in sole possession
of the researcher. Subjects will be assigned a number to maintain confidentiality.
3. Check the appropriate box(es) that describe the subjects you plan to use.
69
Adult volunteers
Mentally Disabled People
CAL University Students
Economically Disadvantaged People
Other Students
Educationally Disadvantaged People
Prisoners
Fetuses or fetal material
Pregnant Women
Children Under 18
Physically Handicapped People
Neonates
4. Is remuneration involved in your project?
5. Is this project part of a grant?
Yes or
Yes or
No
No. If yes, Explain here.
If yes, provide the following information:
Title of the Grant Proposal
Name of the Funding Agency
Dates of the Project Period
6.
Does your project involve the debriefing of those who participated?
Yes or
No
If Yes, explain the debriefing process here.
7. If your project involves a questionnaire interview, ensure that it meets the requirements of
Appendix
in the Policies and Procedures Manual.
70
California University of Pennsylvania Institutional Review Board
Survey/Interview/Questionnaire Consent Checklist (v021209)
This form MUST accompany all IRB review requests
Does your research involve ONLY a survey, interview or questionnaire?
YES—Complete this form
NO—You MUST complete the “Informed Consent Checklist”—skip the remainder
of this form
Does your survey/interview/questionnaire cover letter or explanatory statement include:
(1) Statement about the general nature of the survey and how the data will be
used?
(2) Statement as to who the primary researcher is, including name, phone, and
email address?
(3) FOR ALL STUDENTS: Is the faculty advisor’s name and contact information
provided?
(4) Statement that participation is voluntary?
(5) Statement that participation may be discontinued at any time without penalty
and all data discarded?
(6) Statement that the results are confidential?
(7) Statement that results are anonymous?
(8) Statement as to level of risk anticipated or that minimal risk is anticipated?
(NOTE: If more than minimal risk is anticipated, a full consent form is required—and
the Informed Consent Checklist must be completed)
(9) Statement that returning the survey is an indication of consent to use the data?
(10) Who to contact regarding the project and how to contact this person?
(11) Statement as to where the results will be housed and how maintained? (unless
otherwise approved by the IRB, must be a secure location on University premises)
(12) Is there text equivalent to: “Approved by the California University of
Pennsylvania Institutional Review Board. This approval is effective nn/nn/nn and
expires mm/mm/mm”? (the actual dates will be specified in the approval notice from
the IRB)?
71
(13) FOR ELECTRONIC/WEBSITE SURVEYS: Does the text of the cover letter
or
explanatory statement appear before any data is requested from the participant?
(14) FOR ELECTONIC/WEBSITE SURVEYS: Can the participant discontinue
participation at any point in the process and all data is immediately discarded?
72
California University of Pennsylvania Institutional Review Board
Informed Consent Checklist (v021209)
This form MUST accompany all IRB review requests
Does your research involve ONLY a survey, interview, or questionnaire?
YES—DO NOT complete this form. You MUST complete the
“Survey/Interview/Questionnaire Consent Checklist” instead.
NO—Complete the remainder of this form.
1. Introduction (check each)
(1.1) Is there a statement that the study involves research?
(1.2) Is there an explanation of the purpose of the research?
2. Is the participant. (check each)
(2.1) Given an invitation to participate?
(2.2) Told why he/she was selected.
(2.3) Told the expected duration of the participation.
(2.4) Informed that participation is voluntary?
(2.5) Informed that all records are confidential?
(2.6) Told that he/she may withdraw from the research at any time without
penalty or loss of benefits?
(2.7) 18 years of age or older? (if not, see Section #9, Special Considerations
below)
3. Procedures (check each).
(3.1) Are the procedures identified and explained?
(3.2) Are the procedures that are being investigated clearly identified?
(3.3) Are treatment conditions identified?
4. Risks and discomforts. (check each)
(4.1) Are foreseeable risks or discomforts identified?
(4.2) Is the likelihood of any risks or discomforts identified?
(4.3) Is there a description of the steps that will be taken to minimize any risks or
discomforts?
(4.4) Is there an acknowledgement of potentially unforeseeable risks?
(4.5) Is the participant informed about what treatment or follow up courses of
action are available should there be some physical, emotional, or psychological harm?
(4.6) Is there a description of the benefits, if any, to the participant or to others
that may be reasonably expected from the research and an estimate of the likelihood
of these benefits?
(4.7) Is there a disclosure of any appropriate alternative procedures or courses of
treatment that might be advantageous to the participant?
5. Records and documentation. (check each)
73
(5.1) Is there a statement describing how records will be kept confidential?
(5.2) Is there a statement as to where the records will be kept and that this is a
secure location?
(5.3) Is there a statement as to who will have access to the records?
6. For research involving more than minimal risk (check each),
(6.1) Is there an explanation and description of any compensation and other
medical or counseling treatments that are available if the participants are injured
through participation?
(6.2) Is there a statement where further information can be obtained regarding the
treatments?
(6.3) Is there information regarding who to contact in the event of researchrelated injury?
7. Contacts.(check each)
(7.1) Is the participant given a list of contacts for answers to questions about the
research and the participant’s rights?
(7.2) Is the principal researcher identified with name and phone number and
email address?
(7.3) FOR ALL STUDENTS: Is the faculty advisor’s name and contact
information provided?
8. General Considerations (check each)
(8.1) Is there a statement indicating that the participant is making a decision
whether or not to participate, and that his/her signature indicates that he/she has
decided to participate having read and discussed the information in the informed
consent?
(8.2) Are all technical terms fully explained to the participant?
(8.3) Is the informed consent written at a level that the participant can understand?
(8.4) Is there text equivalent to: “Approved by the California University of
Pennsylvania Institutional Review Board. This approval is effective nn/nn/nn and
expires mm/mm/mm”? (the actual dates will be specified in the approval notice from
the IRB)
9. Specific Considerations (check as appropriate)
(9.1) If the participant is or may become pregnant is there a statement that the
particular treatment or procedure may involve risks, foreseeable or currently
unforeseeable, to the participant or to the embryo or fetus?
(9.2) Is there a statement specifying the circumstances in which the participation
may be terminated by the investigator without the participant’s consent?
(9.3) Are any costs to the participant clearly spelled out?
(9.4) If the participant desires to withdraw from the research, are procedures for
orderly termination spelled out?
74
(9.5) Is there a statement that the Principal Investigator will inform the participant
or any significant new findings developed during the research that may affect them
and influence their willingness to continue participation?
(9.6) Is the participant is less than 18 years of age? If so, a parent or guardian must
sign the consent form and assent must be obtained from the child
Is the consent form written in such a manner that it is clear that the
parent/guardian is giving permission for their child to participate?
Is a child assent form being used?
Does the assent form (if used) clearly indicate that the child can freely refuse
to participate or discontinue participation at any time without penalty or coercion?
(9.7) Are all consent and assent forms written at a level that the intended
participant can understand? (generally, 8th grade level for adults, age-appropriate for
children)
75
California University of Pennsylvania Institutional Review Board
Review Request Checklist (v021209)
This form MUST accompany all IRB review requests.
Unless otherwise specified, ALL items must be present in your review request.
Have you:
(1.0) FOR ALL STUDIES: Completed ALL items on the Review Request Form?
Pay particular attention to:
(1.1) Names and email addresses of all investigators
(1.1.1) FOR ALL STUDENTS: use only your CalU email
address)
(1.1.2) FOR ALL STUDENTS: Name and email address of your
faculty research advisor
(1.2) Project dates (must be in the future—no studies will be approved
which have already begun or scheduled to begin before final IRB approval—
NO EXCEPTIONS)
(1.3) Answered completely and in detail, the questions in items 2a through
2d?
2a: NOTE: No studies can have zero risk, the lowest risk is
“minimal risk”. If more than minimal risk is involved you MUST:
i. Delineate all anticipated risks in detail;
ii. Explain in detail how these risks will be minimized;
iii. Detail the procedures for dealing with adverse outcomes
due to these risks.
iv. Cite peer reviewed references in support of your
explanation.
2b. Complete all items.
2c. Describe informed consent procedures in detail.
2d. NOTE: to maintain security and confidentiality of data, all
study records must be housed in a secure (locked) location ON
UNIVERSITY PREMISES. The actual location (department, office,
etc.) must be specified in your explanation and be listed on any
consent forms or cover letters.
(1.4) Checked all appropriate boxes in Section 3? If participants under the
age of 18 years are to be included (regardless of what the study involves) you
MUST:
(1.4.1) Obtain informed consent from the parent or guardian—
consent forms must be written so that it is clear that the
parent/guardian is giving permission for their child to participate.
(1.4.2) Document how you will obtain assent from the child—
This must be done in an age-appropriate manner. Regardless of
whether the parent/guardian has given permission, a child is
completely free to refuse to participate, so the investigator must
document how the child indicated agreement to participate
(“assent”).
76
(1.5) Included all grant information in section 5?
(1.6) Included ALL signatures?
(2.0) FOR STUDIES INVOLVING MORE THAN JUST SURVEYS,
INTERVIEWS, OR QUESTIONNAIRES:
(2.1) Attached a copy of all consent form(s)?
(2.2) FOR STUDIES INVOLVING INDIVIDUALS LESS THAN 18
YEARS OF AGE: attached a copy of all assent forms (if such a form is used)?
(2.3) Completed and attached a copy of the Consent Form Checklist? (as
appropriate—see that checklist for instructions)
(3.0) FOR STUDIES INVOLVING ONLY SURVEYS, INTERVIEWS, OR
QUESTIONNAIRES:
(3.1) Attached a copy of the cover letter/information sheet?
(3.2) Completed and attached a copy of the
Survey/Interview/Questionnaire Consent Checklist? (see that checklist for
instructions)
(3.3) Attached a copy of the actual survey, interview, or questionnaire
questions in their final form?
(4.0) FOR ALL STUDENTS: Has your faculty research advisor:
(4.1) Thoroughly reviewed and approved your study?
(4.2) Thoroughly reviewed and approved your IRB paperwork? including:
(4.2.1) Review request form,
(4.2.2) All consent forms, (if used)
(4.2.3) All assent forms (if used)
(4.2.4) All Survey/Interview/Questionnaire cover letters (if used)
(4.2.5) All checklists
(4.3) IMPORTANT NOTE: Your advisor’s signature on the review request
form indicates that they have thoroughly reviewed your proposal and verified
that it meets all IRB and University requirements.
(5.0) Have you retained a copy of all submitted documentation for your records?
77
78
Institutional Review Board
California University of Pennsylvania
Psychology Department LRC, Room 310
250 University Avenue
California, PA 15419
instreviewboard@cup.edu
instreviewboard@calu.edu
Robert Skwarecki, Ph.D., CCC-SLP,Chair
Jordan Blair,
Please consider this email as official notification that your proposal titled
“The Effect an ACL Injury Prevention Program on Gluteus Medius Strength
Between Genders” (Proposal #10-029) has been approved by the California
University of Pennsylvania Institutional Review Board as submitted, with
the following stipulation:
-
A screening question or statement indicating that participants must be 18
years of age or older must be present in the consent form and/or
questionnaire.
Once you have made this revision, you may immediately begin data
collection. You do not need to wait for further IRB approval. [At your
earliest convenience, you must forward a copy of the revised consent form
for the Board’s records].
The effective date of the approval is 02-24-2011 and the expiration date is
02-23-2012. These dates must appear on the consent form .
Please note that Federal Policy requires that you notify the IRB promptly
regarding any of the following:
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(1) Any additions or changes in procedures you might wish for your
study (additions or changes must be approved by the IRB before
they are implemented)
(2) Any events that affect the safety or well-being of subjects
(3) Any modifications of your study or other responses that are
necessitated by any events reported in (2).
(4) To continue your research beyond the approval expiration date of
02-23-2012 you must file additional information to be considered
for continuing review. Please contact instreviewboard@cup.edu
Please notify the Board when data collection is complete.
Regards,
Robert Skwarecki, Ph.D., CCC-SLP
Chair, Institutional Review Board
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Appendix C3
Trunk Neuromuscular Training Program
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Trunk Neuromuscular Training Program
Progression 1
Lateral Jump and Hold
Step-Hold
Bosu (Round) Swimmers
BOSU (Round) Double Knee-Hold
Single Leg Lateral Airex Hop-Hold
Single Truck Jump-Soft Landing
Front Lunge
Lunge Jumps
BOSU (FLAT) Double Leg Pelvic
Bridges
Single Leg 90 degree Hop-Hold
BOSU (Round) Lateral Crunch
Box Double Crunch
Swiss Ball Back Hyperextensions
Progression 2
Lateral Jumps
Jump-Single Leg Hold
BOSU (Round) Toe Touch Swimmers
BOSU (Round) Single Knee-Hold
Single Leg Lateral BOSU (Round)
Hop-Hold
Double Tuck Jump
Walking Lunges
Scissor Jumps
BOSU (Flat) Single Leg Pelvic
Bridges
Single Leg 90 degree airex Hop-Hold
Box Lateral Crunch
Box Swivel Double Crunch
Swiss Ball Back Hyperextensions
with Ball Reach
Time
Reps
Sets
8
8
10
R&L Legs
20 sec
4
10
10
10 sec
R&L Legs
R&L Legs
R&L Legs
10
8
10
15
15
Time
Reps
R&L Legs
R&L Legs
Sets
10 sec
8
10
20 sec
8
R&L
R&L
R&L
R&L
Legs
Legs
Legs
Legs
6
10
10 sec
10
R&L Legs
8
10
15
15
R&L Legs
R&L Legs
R&L Legs
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Progression 3
Lateral Hop and Hold
Hop-Hold
Prone bridge (Elbow and Knees) Hip
Extension Opposite Shoulder Flexion
Swiss Ball Bilateral Kneel
Single Leg Lateral BOSU (Round)
Hop-Hold with Ball Catch
Repeated Tuck Jump
Walking Lunges Unilaterally
weighted
Lunge Jumps unilaterally Weighted
BOSU (Flat) Single Leg Pelvic
Bridges with Ball Hold
Single Leg 90 Degree Airex hop-Hold
Reaction Ball Catch
BOSU (Round) Lateral Crunch with
Ball catch
BOSU (Round) Swivel Ball Touches
(Feet UP)
Swiss Ball Hyperextensions with
Back Fly
Progression 4
Lateral Hops
Hop-Hop-Hold
Prone bridge (Elbow and toes) Hip
Extension
Swiss Ball Bilateral Kneel with
Partner Pertubations
Single Leg 4 Way BOSU (Round) HopHold
Side to Side Barrier Tuck Jumps
Walking Lunges with Plate Crossover
Scissor Jumps Unilaterally Weighted
Supine Swiss Ball Hamstring Curl
Single Leg 180 degree Airex HopHold
Swiss Ball Lateral Crunch
BOSU (Round) double crunch
Swiss Ball Hyperextensions with
Ball Reach Lateral
Time
Reps
Sets
8
8
10
R&L Legs
R&L Legs
4
R&L Legs
10
R&L Legs
10
R&L Legs
R&L Legs
6
R&L Legs
8
R&L Legs
20 sec
10 sec
10 sec
15
15
Time
Reps
10 sec
8
10
Sets
R&L Legs
R&L Legs
R&L Legs
20 sec
3
cycles
R&L Legs
10
R&L Legs
10 sec
10 sec
R&L Legs
10
8
15
15
15
R&L Legs
R&L Legs
R&L Legs
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Progression 5
Time
X-Hops
Crossover-Hop-Hop-Hold
Prone bridge (Elbow and toes) Hip
Extension opposite shoulder flexion
Swiss Ball Bilateral Kneel with
Lateral Ball Catch
Single Leg 4 Way BOSU (Round) HopHold With Ball Catch
Side to Side Reaction Barrier Tuck
Jumps
Walking Lunges with Unilateral
Shoulder Press
Scissor Jumps with Ball Swivel
Swivel Russian Hamstring Curl
Single Leg 180 degree Airex HopHold Reaction Ball Catch
Swiss Ball Lateral Crunch with Ball
Catch
BOSU (Round) Swivel Double Crunch
Swiss Ball Hyperextensions with
Lateral Ball Catch
Reps
Sets
6
cycles
8
10
R&L Legs
3
cycles
R&L Legs
10
R&L Legs
R&L Legs
R&L Legs
20 sec
10 sec
10 sec
R&L Legs
10
8
R&L Legs
8
R&L Legs
15
15
R&L Legs
1. Lateral Jumping Progression
Phase I – Lateral Jump and Hold
The subject prepares for this exercise by standing with her
feet close together and her knees slightly bent. The
subject should jump laterally over a line keeping her knees
bent and staying close to the line. When they lands on the
opposite side, they should immediately descend into a deep
hold.
Phase II – Lateral Jumps
The subject prepares for this exercise by standing with
their feet close together and knees slightly bent on one
side of the line. The subject should jump sideways over the
line keeping her knees bent and staying close to the line.
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When the subject lands on the opposite side, they should
immediately redirect back to the initial position. The
subject should repeat this sequence as quickly as they can
while maintaining proper form. When teaching this exercise,
encourage the subject to achieve as many repetitions as
possible in the allotted time by jumping close to the
lines, shortening the ground contact time, and not using
excessive height on the jumps. Do not allow the subject to
perform a double hop on the side of the line. Early in the
training the subject may focus on the line, as their
technique improves encourage them to shift their visual
focus away from the line to outside cues.
Phase III – Lateral Hop and Hold
The subject prepares for this exercise by standing on one
foot and their knee slightly bent. The subject should jump
sideways over a line keeping their knee bent and staying
close to the line. When they land on the opposite side,
they should immediately descend into a single leg deep
hold.
Phase IV – Lateral Hops
The subject prepares for this exercise by standing on one
leg with their knee slightly bent on one side of the line.
The subject should jump sideways over the line keeping
their knee bent and staying close to the line. When the
subject lands on the opposite side, they should immediately
redirect back to the initial position. When teaching this
exercise encourage the subject to achieve as many
repetitions as possible in the allotted time by jumping
close to the lines, shortening the ground contact time, and
not using excessive height on the jumps. Do not allow the
subject to perform a double hop on the side of the line.
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Early in the training the subject may focus on the line, as
her technique improves encourage them to shift their visual
focus away from the line to outside cues.
Phase V – X Hops
The subject begins facing a quadrant pattern standing on a
single limb with their support knee slightly bent. They
will hop diagonally, landing in the opposite quadrant,
maintaining forward stance, and holding the deep knee
flexion landing for three seconds. The subject then hops
laterally into the side quadrant again holding the landing.
Next, the subject will hop diagonally backwards holding the
landing. Finally, they hop laterally into the initial
quadrant holding the landing. The subject should repeat
this figure 8 pattern for the required number of sets.
Encourage the subject to maintain balance during each
landing, keeping her eyes up and their focus away from
their feet.
2. Single-Leg Anterior Progression
Phase I – Step-Hold
The subject starts by taking a quick step forward and
continues by balancing in a deep hold position on the leg
they stepped onto.
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Phase II – Jump-Single Leg Hold
The subject will begin this exercise in the athletic
position. The subject proceeds to jump forward, landing and
balancing on one leg in a deep hold position.
Phase III – Hop-Hold
Starting in a balanced position on one foot, the subject
hops forward, landing and balancing on one leg in a deep
hold position.
Phase IV – Hop-Hop-Hold
The subject hops forward twice quickly, landing and
balancing on one leg in a deep hold position.
Phase V – Crossover-Hop-Hop-Hold
The subject hops forward while alternating legs three times
quickly, landing and balancing on one leg in a deep hold
position.
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3. Prone Trunk Stability Progression
Phase I – BOSU® (Round) Toe Touch Swimmers
The subject begins in a prone position with their abdomen
centered on the round side of the BOSU® and their arms
overhead and legs extended. The subject reaches back with
one arm to touch opposite foot and returns to the
outstretched superman position
Phase II – BOSU® (Round) Swimmers with Partner
Perturbations
The subject begins in prone position with abdomen centered
on the round side of the BOSU® and with their arms overhead
and legs extended. The movement is initiated by elevating
the opposite arm and leg and held for three seconds. A
partner will offer random perturbations by stepping on
different sides of the BOSU® during the exercise.
Phase III – Prone Bridge (Elbows and Knees) Hip Extension
Opposed Shoulder Flexion
The subject begins in prone position with her elbows flexed
and balanced on an Airex pad and knees on the ground. The
movement is initiated by elevating the opposite arm and leg
and held for a single count and finitheyd by returning to
the original position.
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Phase IV – Prone Bridge (Elbows and Toes) Hip Extension
The subject begins in prone position with elbows flexed and
balanced on an Airex pad and toes on the ground. The
movement is initiated by elevating the each leg
individually and held for a single count and finished by
returning to the original position.
Phase V – Prone Bridge (Elbows and Toes) Hip Extension
Opposite Shoulder Flexion
The subject begins in prone position with elbows flexed and
balanced on an Airex pad and toes on the ground. The
movement is initiated by elevating the opposite arm and leg
and held for a single count and finished by returning to
the original position.
4. Kneeling Trunk Stability Progression
Phase I – BOSU® (Round) Double Knee-Hold
The subject begins this exercise by balancing in a kneeling
position with their knees on each side of the round side of
the BOSU®. The subject will maintain this balanced position
with the hips slightly flexed for the duration of the
exercise.
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Phase II – BOSU® (Round) Single Knee-Hold
The subject begins this exercise by balancing in a kneeling
position with one knee directly in the middle of the round
side of the BOSU® and the other knee extended out to the
side. The subject will maintain this balanced position with
the hip slightly flexed for the duration of the exercise.
Phase III – Swiss Ball Bilateral Kneel
The subject kneels and balances on Swiss ball with feet off
the ground. A spotter should be available at all times in
front of the subject
Phase IV – Swiss Ball Bilateral kneel with Partner
Perturbations
The subject kneels and balances on Swiss ball with their
feet off of the ground. Once the subject is stabilized a
partner can perturb the ball by kicking in unanticipated
directions. A spotter should be available at all times in
front of the subject.
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Phase V – Swiss Ball Bilateral Kneel with Lateral Ball
Catch
The subject kneels and balances on Swiss ball with feet off
the ground. A ball should be tossed back and forth with a
partner to increase the difficulty of this exercise. A
spotter should be present next to the subject at all times.
5. Single Leg Lateral Progression
Phase I – Single Leg Lateral AIREX Hop-Hold
Subject starts on one side of the Airex pad and hops
laterally onto the Airex. The subject should maintain
balance and hold the knee in a flexed position. The subject
then hops off the other side of the Airex onto the ground,
maintains balance and then repeats the exercise in the
other direction.
Phase II – Single Leg Lateral BOSU® (Round) Hop-Hold
Subject starts on one side of the BOSU® and hops laterally
onto the BOSU®. The subject should maintain balance and
hold the knee in a flexed position. The subject then hops
off the other side of the BOSU® onto the ground, maintains
balance and then repeats the exercise in the other
direction.
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Phase III – Single Leg Lateral BOSU® (Round) Hop-Hold with
Ball Catch
The subject starts on one side of the BOSU® and hops
laterally onto the BOSU®. The subject should maintain
balance and hold the knee in a flexed position. The subject
then hops off the other side of the BOSU® onto the ground,
maintains balance and then repeats the exercise in the
other direction. The subject is further challenged by
having to catch and return a ball upon each landing.
Phase IV – Single Leg 4 Way BOSU® (Round) Hop-Hold
The subject starts in a single leg athletic position
immediately behind the BOSU®. The subject hops forward onto
the round side of the BOSU® and lands in a balanced
position. After achieving a balanced single leg stance on
the BOSU®, the subject proceeds to hop off the BOSU®
laterally and assumes this same stance on the floor
immediately next to the BOSU®. The subject will then
continue to hop on and off the BOSU®, achieving a balanced
athletic position, in each of the four directions: forward,
backwards, lateral and medial.
Phase V – Single Leg 4 Way BOSU® (Round) Hop-Hold with Ball
Catch
The subject starts in a single leg athletic position
immediately behind the BOSU®. The subject hops forward onto
the round side of the BOSU® and lands in a balanced
position. After achieving a balanced single leg stance on
the BOSU®, the subject proceeds to hop off the BOSU®
laterally and assumes this same stance on the floor
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immediately next to the BOSU®. The subject will then
continue to hop on and off the BOSU®, achieving a balanced
athletic position, in each of the four directions: forward,
backwards, lateral and medial. A ball should be tossed back
and forth with a partner upon landing to increase the
difficulty of this exercise.
6. Tuck Jump Progression
Phase I - Single Tuck Jump Soft Landing
The subject starts in the athletic position with their feet
shoulder width apart. The subject initiates a vertical jump
with a slight crouch downward while they extends their arms
behind them. The subject then swings their arms forward as
they simultaneously jumps straight up and pulls their knees
up as high as possible. At the highest point of the jump
the subject should be positioned in the air with their
thighs parallel to the ground. On landing, the subject
should land softly, using a toe to mid-foot rocker landing.
The subject should not continue this jump if they cannot
control the high landing force or keep their knees aligned
during landing. If the subject is unable to raise the knees
to the proper height, it may be valuable to instruct them
to “grasp the knees and they bring the thighs to
horizontal.”
Phase II – Double Tuck Jump
Similar to the single tuck jump described above but with an
additional jump performed immediately after the first jump.
The subject should focus on maintaining good form and
minimizing time on the ground between jumps.
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Phase III – Repeated Tuck Jumps
The subject starts in the athletic position with their feet
shoulder width apart. The subject initiates a vertical jump
with a slight crouch downward while they extends their arms
behind them. The subject then swings their arms forward as
they simultaneously jump straight up and pull their knees
up as high as possible. At the highest point of the jump
the subject should be positioned in the air with their
thighs parallel to the ground. When landing the subject
should immediately begin the next tuck jump.
Phase IV – Side to Side Tuck Jumps
The subject starts in the athletic position with their feet
shoulder width apart. The subject initiates a vertical jump
over a barrier with a slight crouch downward while they
extends their arms behind them. The subject then swings
their arms forward as they simultaneously jump straight up
and pull their knees up as high as possible. At the highest
point of the jump the subject should be positioned in the
air with their thighs parallel to the ground. When landing,
the subject should immediately begin the next tuck jump
back to the other side of the barrier.
Phase V – Side to Side Reaction Barrier Tuck Jumps
The subject starts in the athletic position with their feet
shoulder width apart. The subject initiates a vertical jump
over a barrier with a slight crouch downward while they
extend their arms behind them. The subject then swings
their arms forward as they simultaneously jump straight up
and pull their knees up as high as possible. At the highest
point of the jump the subject should be positioned in the
94
air with their thighs parallel to the ground. When landing
the subject should immediately begin the next tuck jump.
When prompted, the subject should jump to the other side of
the barrier without breaking rhythm.
7. Lunge Progression
Phase I – Front Lunges
The subject begins by stepping forward from a standing
position. The step should be exaggerated in length to the
point that their front leg is positioned with the knee
flexed to 90° and the lower leg completely vertical. The
back leg should be as straight as possible and the torso
upright. Emphasis should be placed on getting the hips as
low as possible while maintaining the previously described
body position. The exercise is completed by driving off the
front leg and returning to the original position.
Phase II – Walking Lunges
The subject performs a lunge and instead of returning to
the start position they step through with the back limb and
proceed forward with a lunge on the opposite limb.
Encourage the subject to lunge their front limb far enough
out so that their knee does not advance beyond their ankle
during the exercise. An alternative coaching method is to
instruct the subject to attempt to maintain a constant low
center of gravity and roll through the lunges. This
increases the intensity of the exercise and attempts to
mimic motions frequently occurring in sports.
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Phase III – Walking Lunges Unilaterally Weighted
The subject performs a lunge and instead of returning to
the start position they steps through with the back limb
and proceeds forward with a lunge on the opposite limb
while holding a dumbbell in one hand. Encourage the subject
to lunge their front limb far enough out so that their knee
does not advance beyond her ankle during the exercise. This
exercise is then repeated with the dumbbell in the opposite
hand.
Phase IV – Walking Lunges with Plate Crossover
The subject performs a lunge and instead of returning to
the start position they steps through with the back limb
and proceeds forward with a lunge on the opposite limb
while reaching with a weight plate to the open side of the
body. Encourage the subject to lunge their front limb far
enough out so that their knee does not advance beyond her
ankle during the exercise.
Phase V – Walking Lunges with Unilateral Shoulder Press
The subject performs a lunge and instead of returning to
the start position they steps through with the back limb
and proceeds forward with a lunge on the opposite limb
while pressing a dumbbell above her head. The weight should
move up and down with the same tempo and direction as the
lunge. Encourage the subject to lunge their front limb far
96
enough out so that their knee does not advance beyond their
ankle during the exercise.
8. Lunge Jump Progression
Phase I – Lunge Jumps
The subject starts in an extended stride position with
the hips pushed forward, and the front knee positioned
directly above the ankle and flexed to 90°. The back leg
is fully extended at the hip and knee providing minimal
support for the stance. The subject should jump
vertically off of the front support leg maintaining the
starting position during flight and landing. The jump is
repeated as quickly as possible while still achieving
maximum vertical height. To coach this jump, encourage
the subject to keep the back leg straight and use it only
for balance support. Vertical power is obtained by the
front leg. Stance support percentages are approximately
80% for the front leg and 20% for the back.
Phase II – Scissor Jumps
The subject starts in an extended stride position with the
hips pushed forward, and the front knee positioned directly
above the ankle and flexed to 90°. The back leg is fully
extended at the hip and knee providing minimal support for
the stance. The subject should jump vertically off of the
front support leg and switch the position of the legs while
in flight. The jump is repeated as quickly as possible
while still achieving maximum vertical height. The subject
will be jumping off alternate legs on each jump during this
exercise.
97
Phase III – Lunge Jumps Unilaterally Weighted
The subject starts in an extended stride position with
their hips pushed forward, and the front knee positioned
directly above the ankle and flexed to 90°. The back leg is
fully extended at the hip and knee providing minimal
support for the stance. The subject should jump vertically
off of the front support leg maintaining the starting
position during flight and landing. The jump is repeated as
quickly as possible while still achieving maximum vertical
height. To unilaterally weight this exercise a dumbbell
should be held in one hand. This exercise is then repeated
with the dumbbell in the opposite hand.
Phase IV – Scissor Jumps Unilaterally Weighted
The subject starts in an extended stride position with the
hips pushed forward, and the front knee positioned directly
above the ankle and flexed to 90°. The back leg is fully
extended at the hip and knee providing minimal support for
the stance. The subject should jump vertically off of the
front support leg and switch the position of the legs while
in flight. The jump is repeated as quickly as possible,
while still achieving maximum vertical height. To
unilaterally weight this exercise, a dumbbell should be
held in one hand. The subject will be jumping off alternate
legs on each jump during this exercise. This exercise is
then repeated with the dumbbell in the opposite hand.
98
Phase V – Scissor Jumps with Ball Swivel
The subject starts in an extended stride position with the
hips pushed forward, and the front knee positioned directly
above the ankle and flexed to 90°. The back leg is fully
extended at the hip and knee providing minimal support for
the stance. The subject should jump vertically off of the
front support leg and switch the position of the legs while
in flight. The jump is repeated as quickly as possible
while still achieving maximum vertical height. To
unilaterally weight this exercise, a medicine ball should
be swiveled to the open side of the body during each jump.
The subject will be jumping off alternate legs
9. Hamstring Specific Progression
Phase I – BOSU® (Flat) Pelvic Bridge
The subject lays supine with their hip and knees flexed and
their feet planted on the flat side of the BOSU®. The
subject then extends their hips and elevates their trunk
off the ground to execute a pelvic bridge. This position
should be held for 3 seconds prior to repeating the next
repetition.
Phase II – BOSU® (Flat) Single Leg Pelvic Bridge
The subject lays supine with their hip and knees flexed and
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a single foot planted on the flat side of the BOSU® and the
contralateral (opposite) leg fully extended. The subject
then extends their hips and elevates their trunk off the
ground to execute a pelvic bridge. This position should be
held for 3 seconds prior to repeating the next repetition.
Phase III – BOSU® (Flat) Single Leg Pelvic Bridge
The subject lays supine with their hip and knees flexed and
a single foot planted on the flat side of the BOSU® and the
contralateral (opposite) leg fully extended holding a ball
directly above her in her hands. The subject then extends
their hips and elevates their trunk off the ground to
execute a pelvic bridge. This position should be held for 3
seconds prior to repeating the next repetition.
Phase IV – Supine Swiss Ball Hamstring Curl
The subject lays supine with their hip and knees flexed
with both heels planted on top of a Swiss ball. The subject
then extends their hips and elevates their trunk off the
ground while pulling her heels in to her buttocks.
Phase V – Russian Hamstring Curl with Lateral Touch
The subject begins in a kneeling position with a partner
providing foot support and torso support (with band
100
assistance). The subject extends at the knee to lower their
torso towards the ground. Once touching the BOSU® with
their chest the subject swivels their trunk and returns to
the original position. The coach should provide enough
assistance so that the exercise can be performed without
flexing at the hip.
10. Single Leg Rotatory progression
Phase I – Single Leg 90° Hop-Hold
The starting position for this jump is with the subject in
a semi-crouched position on the single limb being trained.
The jump should focus on attaining maximum height while
maintaining good form upon landing. During the flight
phase, the subject should rotate 90°. The landing occurs on
the same leg and should be performed with deep knee flexion
(to 90°). The landing should be held for a minimum of three
seconds to be counted as a successful landing. Coach this
jump with care to protect the subject from injury. Start
the subject with a sub maximal effort so they can
experience the difficulty of the jump. Continue to increase
the intensity of the jump as the subject improves their
ability to stick and hold the final landing. Have the
subject keep their focus away from their feet, to help
prevent too much forward lean.
Phase II – Single Leg 90° AIREX Hop-Hold
The starting position for this jump is with the subject in
a semi-crouched position on the single limb being trained.
101
The jump should focus on attaining maximum height while
maintaining good form upon landing. During the flight phase
the subject should rotate 90°. The landing occurs on the
same leg and should be performed with deep knee flexion (to
90°). The landing should be held for a minimum of three
seconds on an AIREX pad to be counted as a successful
landing. Coach this jump with care to protect the subject
from injury.
Phase III – Single Leg 90° Hop-Hold Reaction Ball Catch
The starting position for this jump is with the subject in
a semi-crouched position on the single limb being trained.
The jump should focus on attaining maximum height while
maintaining good form upon landing. During the flight phase
the subject should rotate 90°. The landing occurs on the
same leg and should be performed with deep knee flexion (to
90°). The landing should be held for a minimum of three
seconds on an AIREX pad to be counted as a successful
landing. Upon landing a ball will be passed back and forth
with the subject to increase the difficulty of a successful
landing.
Phase IV – Single Leg 180° AIREX Hop-Hold
The starting position for this jump is with the subject in
a semi-crouched position on the single limb being trained.
The jump should focus on attaining maximum height while
maintaining good form upon landing. During the flight phase
the subject should rotate 180°. The landing occurs on the
same leg and should be performed with deep knee flexion (to
90°). The landing should be held for a minimum of three
seconds on an AIREX pad to be counted as a successful
landing.
102
Phase V – Single Leg 180° AIREX Hop-Hold Reaction Ball
Catch
The starting position for this jump is with the subject in
a semi-crouched position on the single limb being trained.
The jump should focus on attaining maximum height while
maintaining good form upon landing. During the flight phase
the subject should rotate 180°. The landing occurs on the
same leg and should be performed with deep knee flexion (to
90°). The landing should be held for a minimum of three
seconds on an AIREX pad to be counted as a successful
landing. Upon landing a ball will be passed back and forth
with the subject to increase the difficulty of a successful
landing.
11. Lateral Trunk Progression
Phase I – BOSU® (Round) Lateral Crunch
The subject starts lying on their side with their hip
located in the center of the round side of the BOSU®. The
subject’s feet and legs must be anchored during this
exercise by the trainer or a stationary object. The subject
will proceed to bend laterally at the waist back and forth
for the prescribed repetitions.
Phase II – Box Lateral Crunch
Subject starts in a supine position on a plyo box with arms
placed on the back of the head. The subject flexes their
trunk simultaneous with their flexion. As the trunk and hip
are maximally flexed, the subject rotates at the trunk
touching each elbow to the opposite knee.
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Phase III – BOSU® (Round) Lateral Crunch with Ball Catch
Subject starts lying on side with hip located top of the
round side of a BOSU®. The subject’s feet and legs must be
anchored during this exercise by the trainer or a
stationary object. The subject will proceed to bend
laterally at the waist back and forth for the prescribed
repetitions. A ball should be tossed back and forth with a
partner to increase the difficulty of this exercise.
Phase IV – Swiss Ball Lateral Crunch
Subject starts lying on side with hip located top of a
Swiss ball. The subject’s feet and legs must be anchored
during this exercise by the trainer or a stationary object.
The subject will proceed to bend laterally at the waist
back and forth for the prescribed repetitions.
Phase V – Swiss Ball Lateral Crunch with Ball Catch
Subject starts lying on side with hip located top of a
Swiss ball. The subject’s feet and legs must be anchored
during this exercise by the trainer or a stationary object.
The subject will proceed to bend laterally at the waist
back and forth for the prescribed repetitions. A ball
should be tossed back and forth with a partner to increase
the difficulty of this exercise.
12. Trunk Flexion Progression
Phase I – Box Double Crunch
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The subject starts out supine on a plyometric box or
similar object and flexes their trunk simultaneous with hip
flexion.
Phase II – Box Swivel Double Crunch
Subject starts in a supine position on a plyo box with arms
placed across chest. The subject flexes their trunk
simultaneous with hip flexion. As the trunk and hip are
maximally flexed, the subject rotates at the trunk touching
each elbow to the opposite knee.
Phase III – BOSU® (Round) Swivel Ball Touches (Feet up)
Subject starts sitting on the round side of a BOSU® holding
a medicine ball. The subject will proceed to swivel at the
trunk to touch the medicine ball to the floor for each
repetition.
Phase IV – BOSU® (Round) Double Crunch
Subject starts sitting on the round side of a BOSU®. The
subject flexes their trunk simultaneous with hip flexion.
105
Phase V – BOSU® (Round) Swivel Double Crunch
Subject starts sitting on the round side of a BOSU®. The
subject flexes her trunk simultaneous with hip flexion. As
the trunk and hip are maximally flexed, the subject rotates
at the trunk touching each elbow to the opposite knee.
13. Trunk Extension Progression
Phase I – Swiss Ball Back Hyperextensions
The subject begins in a prone position on the Swiss ball
with their hips centered on top of the Swiss ball and a
partner anchoring their feet to the floor. The movement is
initiated by extending htheirer hips and lower back to
bring the subject into a position of slight hyperextension.
The position should be maintained for a short pause and
then returned to the flexed position.
Phase II – Swiss Ball Back Hyperextensions with Ball Reach
The subject begins in a prone position on the Swiss ball
with their hips centered on top of the Swiss ball and a
partner anchoring their feet to the floor. The movement is
initiated by extending hips and lower back to bring the
subject into a position of slight hyperextension. While
performing this motion the subject will also extend and
return a medicine ball from the chest to full shoulder and
elbow extension and back to the chest.
Phase III – Swiss Ball Hyperextensions with Back Fly
106
The subject begins in a prone position on the Swiss ball
with their hips centered on top of the Swiss ball and a
partner anchoring their feet to the floor. The movement is
initiated by extending hips and lower back to bring the
subject into a position of slight hyperextension. The
position should be maintained while the subject brings
dumbbells out to the side similar to a back fly exercise.
Phase IV – Swiss Ball Hyperextensions with Ball Reach
Lateral
The subject begins in a prone position on the Swiss ball
with their hips centered on top of the Swiss ball and a
partner anchoring their feet to the floor. The movement is
initiated by extending hips and lower back to bring the
subject into a position of slight hyperextension. The
position should be maintained while the subject brings a
medicine ball above their head and slightly to the side.
Phase V – Swiss Ball Hyperextensions with Lateral Ball
Catch
The subject begins in a prone position on the Swiss ball
with their hips centered on top of the Swiss ball and a
partner anchoring their feet to the floor. The movement is
initiated by extending hips and lower back to bring the
subject into a position of slight hyperextension. The
position should be maintained while the subject brings a
medicine ball above her head and slightly to the side. A
ball should be tossed back and forth with a partner to
increase the difficulty of this exercise
107
Appendix C4
Physical Activity Readiness Questionnaire
108
Physical Activity Readiness Questionnaire (PAR-Q) and You
Regular physical activity is fun and healthy, and increasingly more
people are starting to become more
active every day. Being more active is very safe for most people.
However, some people should check with
their doctor before they start becoming much more physically active.
If you are planning to become much more physically active than you
are now, start by answering the
seven questions in the box below. If you are between the ages of 15
and 69, the PAR-Q will tell you if you
should check with your doctor before you start. If you are over 69
years of age, and you are not used to being
very active, check with your doctor.
Common sense is your best guide when you answer these questions.
Please read the questions carefully
and answer each one honestly:
YES NO
..1. Has your doctor ever said that you have a heart condition and
that you should only do physical activity recommended by a doctor?
..2. Do you feel pain in your chest when you do physical activity?
..3. In the past month, have you had chest pain when you were not
doing physical activity?
..4. Do you lose your balance because of dizziness or do you ever
lose consciousness?
..5. Do you have a bone or joint problem that could be made worse by
a change in your physical activity?
..6. Is your doctor currently prescribing drugs (for example, water
pills) for your blood pressure or heart condition?
..7. Do you know of any other reason why you should not do physical
activity?
NO to all questions Delay becoming much more active:
.If you are not feeling well because of a temporary illness such as
a cold or a fever – wait until you feel better; or
.If you are or may be pregnant – talk to your doctor before you
start becoming more active.
Please note: If your health changes so that you then answer YES to
any of the above questions, tell your fitness or health
professional.
Ask whether you should change your physical activity plan if you
answered: YES to one or more questions
If you answered NO honestly to all PAR-Q questions, you can be
reasonably sure that you can:
.Start becoming much more physically active – begin slowly and build
up gradually. This is the safest and easiest way to go.
109
.Take part in a fitness appraisal – this is an excellent way to
determine your basic fitness so that you can plan the best way for
you to live actively.
Talk to your doctor by phone or in person BEFORE you start becoming
much more physically active or BEFORE you have a fitness appraisal.
Tell your doctor about the PAR-Q and which questions you answered
YES.
.You may be able to do any activity you want – as long as you start
slowly and build up gradually. Or, you may need to restrict your
activities to those which are safe for you. Talk with your doctor
about the kinds of activities you wish to participate in and follow
his/her advice.
.Find out which community programs are safe and helpful for you.
Informed use of the PAR-Q: Reprinted from ACSM’s Health/Fitness
Facility Standards and Guidelines, 1997 by American College of
Sports Medicine
110
Appendix C5
Demographic Information
111
Demographic Information
Subject #_______
Age: __________________________
Year school: __________________
Gender:
Male or Female (Circle one)
Do you participate in Physical activity for 30 minutes at
least three times a week? Yes or No
(Circle One)
Which leg do you kick a ball with?
Right or Left (Circle One)
Have you sustained a lower extremity injury within the past
6 months?
Yes
Or
No
(Circle One)
Do you suffer from any neuromuscular disorders that you
know of?
Yes
Or
No
(Circle One)
Do you have any balance problems?
Yes
Or
No
(Circle One)
Has a doctor ever told you to not exercise?
Yes
Or
No
(Circle One)
Do you have any other health conditions?
Yes
Or
No
(Circle One)
If Yes, please
explain:___________________________________________________
___________________________________________________________
___________________________________________________________
___________
112
Appendix C6
Subject Testing Sheet
113
Subject Testing Sheet
Subject #_______
Gender_______
Group_______
Gluteus Medius Peak Force (lbs)
Distance from hip to knee__________m
Weight_________(lbs)/ =___________kg
Practice Trial
Trial 1
Trial 2
Trial 3
Mean Peak
force
Left
Leg
Right
Leg
Equation
Left Mean Peak Force (____________lbs) x 4.45 = ______________N
Right Mean Peak Force (______________lbs) x 4.45=_______________N
Gluteus Medius Peak Force (lbs)
Distance from hip to knee__________m
Weight_________(lbs)/ =___________kg
Practice Trial
Trial 1
Trial 2
Trial 3
Left
Leg
Right
Leg
Equation
Left Mean Peak Force (____________lbs) x 4.45 = ______________N
Right Mean Peak Force (______________lbs) x 4.45=_______________N
Mean Peak
force
114
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ABSTRACT
Title:
THE EFFECT OF AN ACL INJURY PREVENTION
PROGRAM ON GLUTEUS MEDIUS STRENGTH BETWEEN
GENDERS
Researcher:
Jordan Blair
Advisor:
Dr. Shelly DiCesaro
Date:
May 2011
Research Type: Master’s Thesis
Context:
Current research indicates the gluteus
medius as an important muscle in the
prevention of ACL injuries. Previous
studies have not examined the effects of an
ACL injury prevention programs’ effect on
gluteus medius strength, nor if there is a
difference in benefits received from an ACL
injury prevention program between genders.
Objective:
The purpose of this study was to examine the
effect of an ACL injury prevention program
on gluteus medius strength as well as
strength gains from the implementation of
the program between males and females.
Design:
Quasi-experimental pre-test and post-test.
Setting:
Testing was performed in a controlled
laboratory setting by the researcher.
Participants:
Twenty-four physically active college
students (male=12, female=12) that were
injury free volunteered for this study.
Interventions: Subjects were randomly placed into an
experimental or control group. All
subjects’ gluteus medius strength was tested
bilaterally at the beginning and end of a
six week period in which the experimental
group underwent an ACL injury prevention
training protocol for 12 sessions twice a
week.
121
Main Outcome Measures:
Gluteus medius strength was assessed at the
end of the six weeks and compared between
experimental and control groups as well as
males and females in the experimental group.
Results:
A significant difference in gluteus medius
strength was found between the experimental
and control groups (t = 2.697, p = .016).
There was not a significant difference in
gluteus medius strength between genders in
the experimental group (t = -0.665, p =
0.527).
Conclusion:
The implementation of a six week ACL injury
prevention program significantly improved
average gluteus medius strength, while
average gluteus medius strength was not
significantly difference between males and
females in the experimental group. This
suggests males and females benefit similarly
from this ACL injury prevention program and
the widespread use of this ACL injury
prevention program may potentially decrease
ACL injuries
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