A CORRELATION BETWEEN MUSCULAR IMBALANCES OF THE LOWER
EXTREMITY (H:Q RATIO) AND FORCE PRODUCTION

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
James Thomas Daley

Research Advisor, Dr. Edwin Zuchelkowski
California, Pennsylvania
April 23, 2009

iii
ACKNOWLEDGEMENTS
It is with great thanks to many others that I first
and foremost thank my classmates, for their support,
guidance, motivation and encouragement throughout a year
filled with long hours in the clinic, on the field and in
the classroom. We have all grown so much throughout this
process and I thank you for helping me along the way.
I thank my family and friends for the support and love
that you have continued to give me wherever I have landed.
Each chapter of life is a new journey for all of us and
being there along with me has made it that much more
special.
To Dr. Edwin Zuchelkowski, I thank you for the time
that you have invested in my work throughout this year,
beginning in the early summer. I also thank you for the
freedom and criticism that you have provided throughout our
time together. It has shaped me for the better and forces
me everyday to continue to think critically. Thank you for
your excitement and vigor for new research and the wisdom
that you have in regards to research that has already been
done.
To Dr. Shelly DiCesaro, I thank you for your patience,
for your always-willing attitude towards your students and
for your work ethic. Thank you for the guidance each day
to help course correct my travels. Without your help, my
research and my time here would not be what it is today.
Thank you for always lending a hand with whatever it may be
and for a smile each day.
Mr. Mike Meyer, Thank you for giving me the ability to
succeed. I see your work ethic and it certainly reflects
who you are. I was beyond pleased when you agreed to be
part of my committee because of your critical eye, thirst
for what comes next, and need for how the application of
research is relevant. You have always made me think how
this will help our profession with my research, but it is
something that I have carried along to every advancement or
idea that I now have.
Dr. Thomas F. West, Thank you for always getting back
to me about my needs and concerns. Without your support
and willingness to sit and figure out the conflicts, I
would still be performing data collection. Even when you
didn’t have the answer, you always provided the avenue to
find it. Thank you for a great experience here at
California University of Pennsylvania and I fully
appreciate all the big and little things that you have done
for my classmates, the program, and me.

iv
Dr. Jamie Weary, it has been a team effort from Day 1.
I thank you for your willingness to always accomplish the
task no matter what it takes and for your understanding
throughout the year. I thank you for the experience that I
have had here and for the time you have provided me for
academics, counsel and the ever expanding opportunity to
grow.
To all of those that have also shaped my research and
the completion of it, I thank you; specifically, Dr. Robert
Kane, Ms. Carolyn Robinson, and Mr. Eric Schussler. Thank
you all for your guidance, concern for my success and
helpfulness throughout the process. Thank you to the
California University of Pennsylvania community for the
resources, opportunities, and abilities that you have
bestowed upon me. I am forever indebted.

v
TABLE OF CONTENTS
Page
SIGNATURE PAGE

. . . . . . . . . . . . . . . . ii

AKNOWLEDGEMENTS . . . . . . . . . . . . . . . . iii
TABLE OF CONTENTS

. . . . . . . . . . . . . . . v

LIST OF TABLES

. . . . . . . . . . . . . . . . vii

INTRODUCTION .

. . . . . . . . . . . . . . . . 1

METHODS

. . . . . . . . . . . . . . . . . . . 5

RESEARCH DESIGN
SUBJECTS

. . . . . . . . . . . . . . . 5

. . . . . . . . . . . . . . . . . . 6

INSTRUMENTATION
PROCEDURES

. . . . . . . . . . . . . . . 7

. . . . . . . . . . . . . . . . . 10

HYPOTHESES. . . . . . . . . . . . . . . . . . 14
DATA ANALYSIS
RESULTS

. . . . . . . . . . . . . . . . 15

. . . . . . . . . . . . . . . . . . . 16

DEMOGRAPHIC DATA . . . . . . . . . . . . . . . 16
HYPOTHESIS TESTING

. . . . . . . . . . . . . . 17

ADDITIONAL FINDINGS . . . . . . . . . . . . . . 20
DISCUSSION . . . . . . . . . . . . . . . . . . 28
DISCUSSION OF RESULTS . . . . . . . . . . . . . 28
CONCLUSIONS . . . . . . . . . . . . . . . . . 31
RECOMMENDATIONS

. . . . . . . . . . . . . . . 33

REFERENCES . . . . . . . . . . . . . . . . . . 35
APPENDICES .

. . . . . . . . . . . . . . . . . 36

vi
APPENDIX A: Review of Literature

. . . . . . . . . 37

APPENDIX B: The Problem . . . . . . . . . . . . . 50
APPENDIX C: Additional Methods . . . . . . . . . . 56
Biodex Dynamometer Set-up Protocol (C1) . . . . . . 57
ACSM’s Gu idelin es for Exerc is e Testing (C2) . . 59
Informed Consent (C3) . . . . . . . . . . . . . . 61
General Demographic Sheet (C4)

. . . . . . . . . 70

Modified PAR-Q Form (C5) . . . . .

.

. . . . . . 71

Institutional Review Board (C6) . .

.

. . . . . . 73

REFERENCES . . . . . . . . . . . . . . . . . . 80
ABSTRACT

. . . . . . . . . . . . . . . . . . 83

vii

LIST OF TABLES
Table

Title

Page

1

Characteristics of Participants

16

2

Participants’ Class Rank

17

3

Pearson Correlation for H:Q Ratio Deviation
Average (H:QDAVG) and Peak Jump Force (PJF)

18

4

Pearson Correlation for H:Q Ratio Deviation
Average (H:QDAVG) and Peak Landing Force (PLF)

18

5.1

Group Statistics of Average Bilateral Change
between the Landing and Jumping Phases
(ABSBIDELTA) on Muscular Imbalance Presence

20

5.2

Independent-sample t-test of Average Bilateral
Change between the Landing and Jumping Phases
(ABSBIDELTA) on Muscular Imbalance Presence

20

6.1

Descriptive Statistics of Overall Quadriceps
21
Driven (AVGOVRDRVN) Group on Peak Jump Force (PJF)
Performance

6.2

Pearson Correlation for Overall Quadriceps
21
Driven (AVGOVRDRVN) Group on Peak Jump Force (PJF)
Performance

7.1

Descriptive Statistics of Overall Quadriceps
Driven (AVGOVRDRVN) Group on Peak Landing Force
(PLF) Performance

22

7.2

Pearson Correlation for Overall Quadriceps
Driven (AVGOVRDRVN) Group on Peak Landing Force
(PLF) Performance

23

8.1

Descriptive Statistics of Overall Hamstring
Driven (AVGOVRDRVN) Group on Peak Jump Force
(PJF) Performance

24

8.2

Pearson Correlation for Overall Hamstring
Driven (AVGOVRDRVN) Group on Peak Jump Force
(PJF) Performance

24

viii

9.1

Descriptive statistics of Overall Hamstring
Driven (AVGOVRDRVN) Group on Peak Landing Force
(PLF) Performance

25

9.2

Pearson Correlation for Overall Hamstring
Driven (AVGOVRDRVN) Group on Peak Landing Force
PLF) Performance

25

10.

Pearson Correlation for Overall Quadriceps Driven
(AVGOVRDRVN) Group on Peak Landing Force (PLF)
Performance vs. Peak Jump Force (PJF) Performance

26

11.

Pearson Correlation for Overall Hamstring Driven
(AVGOVRDRVN) Group on Peak Landing Force (PLF)
Performance vs. Peak Jump Force (PJF) Performance

27

12.

Additional Numeric Findings

27

1
INTRODUCTION

Each and every day, we perform tasks that are of
second nature to us.

These tasks may seem miniscule and

effortless, however they require muscular strength,
recruitment, coordination and balance.

The repetition of a

singular or similar movement over a prolonged period of
time may lead to significant damage to the human body.
Muscular imbalance, which can occur between any agonist and
antagonist, is a ratio of force production that becomes
“unbalanced” where one group of prime movers is producing
more force or higher strength than normal, compared to the
other groups. Although the causes of muscular strength
imbalances in the population are diverse, it seems logical
to assume that muscular strength imbalances could be
present in both athletes and non-athletes of both genders.
This is especially likely considering the vast number of
factors that may lead to developing a muscular strength
imbalance.

These components may include overtraining, task

repetition, and lack of integrated strength training.
An exhaustive search of the literature suggests there
have been no studies that have investigated muscular
strength imbalances comparing non-athletes and premiere
athletes or if one group is more likely to develop a

2
muscular strength imbalance. Presently, research has
primarily been focused on determining how a muscular
strength imbalance of the lower extremities can increase
injury rates of certain populations such as females and
athletes. Current theories suggest that muscular strength
imbalances predispose athletes to higher rates of injury;
therefore having the potential to decrease playing time,
leading to decreased performance. There is currently little
agreement in the literature to quantify the amount of
muscular strength imbalance that must be present before a
detrimental effect is seen in an athlete’s performance, or
if a specific imbalance ratio can clearly indicate the
likeliness of sustaining an injury.1
Previous research has determined the fact that
muscular imbalances can lead to injury; however, little
research has been found showing quantitative data on how a
muscle imbalance can affect sport-specific movements.

It

is important to collect this data because not only will it
result in increased knowledge of the topic data but could
help in redefining the accepted hamstring: quadriceps
ratios of certain populations, most closely researched by
Perrin et al, and Coombs et al.

2,3

Perrin et al has

determined in his works on isokinetic exercise and
assessment that general populations fall into a H:Q ratio

3
of .60.

2

Coombs et al, questions the usage of H:Q ratios

and how it is used to interpret muscle balance or symmetry.
The complaint is that the joint angle has never been
factored into the normative value of 0.6.

This debate will

continue until more research continues to accept or refute
the currently accepted ratio.3
To prevent the potential negative effects of muscular
imbalances,

more

neuromuscular
balanced
groups.4
effects

training

ratio
The
of

attention
and

between

needs

to

be

rehabilitation

agonist

and

purpose

of

this

study

hamstring

to

quadriceps

is

focused
to

achieve

antagonist
to

(H:Q)

on

muscle

determine
ratio

a

the

muscular

imbalances on force production during the vertical jump and
landing phases of drop-jump testing.
The
assess

current

how

research

muscular

will attempt

imbalances

affect

to

quantitatively

force

production,

force attenuation and certain movement patterns associated
with sport performance.

Previous research has determined

the potential negative effects of muscular imbalances and
the increased rate of injury they include. However, the
normal values of H:Q ratio as stated by Perrin et al at 60%
are

outdated

population.2

and
The

include
purpose

a
of

sample
the

size

current

of

the

research

general
is

to

4
examine

the

relationship between

muscular

imbalances

their effect on force production during a drop-jump test.

and

5

METHODS

In order to determine the prevalence of muscular
imbalances and their effect on force production (jumping
force and landing force), a series of tests were conducted.
The study required the participants to complete a brief
warm-up, a series of drop to vertical jumps on a force
platform, and a muscular strength test on a Biodex
isokinetic dynamometer.

This section includes the research

design, subject selection, instrumentation, procedures,
hypotheses, and data analysis.

Research Design

The research was conducted utilizing a cross-sectional
observational, within subjects design.

Relationships were

assessed between participants based upon presence of
muscular imbalance, landing force production, vertical
jumping force production and change in rectus femoris knee
angle.

6
Subjects

A total of 30 volunteers (16 males and 14 females), 18
years of age or older were used for this study. The fulltime California University of Pennsylvania students were
required to be considered apparently healthy, according to
American College of Sports Medicine (ACSM) standards, and
also have completed the modified PAR-Q form.5 Each subject
was required to fall into a “physically active” category.
This definition reads that each research subject
participates in physical activity that raises their heart
rate to at least 50% maximum (i.e. aerobics, organized
sport, weight training) at least three times per week and
must not have suffered from any major or long-term
debilitative injuries to the lower extremities.
Exclusion criteria consist of participants not
fulfilling the requirements of minimum physical activity
per week. Participants were also excluded if they currently
had any injuries that required surgical intervention, or
injuries that would impede their ability to complete
physical tasks that are required by the study or are not
considered apparently healthy, according to ACSM standards.5
Participants were also excluded from this study if they
were currently suffering from any illnesses which may have

7
significantly limited their ability to perform physical
tasks to the best of their ability.

Instrumentation

•

Biodex Isokinetic Dynamometer System 3
Biodex Medical Systems
20 Ramsay Road, Shirley, New York, 11967-4704

The Biodex Isokinetic Dynamometer System 3 was used
to test each participant, bilaterally, for lower
extremity strength, torque values and to measure H:Q
ratio. This was accomplished through a custom 3speed test for seated knee flexion and extension.
•

Force Platform
Advanced Mechanical Technology, Inc.
176 Waltham St. Watertown, MA, 02472-4800
AMTI Serial #- 5386
Model Number- OR6-7-2000
Type- High Frequency

The force platform from AMTI was used as a landing
and take-off point for each trial of the drop-jump
test. It recorded the peak jump and landing force
in Newtons.
•

Stationary Bike
Monark 828E Ergomedic

The Monark Ergomedic was used as the warm-up portion
of the research study. Each participant was
required to ride at 60 rpms till their heart rate
reached 50% of their maximum heart rate, equated by
Karvonen’s equation.

8
•

Digital Video Camera
Panasonic HandyCam DV Camcorder
DCR-PC120 NTSC
Panasonic MiniDV ME DVM69 Cassette

The Panasonic HandyCam DV Camcorder was used as the
video recorder for the video analysis portion of the
research study. Each participant was recorded
performing each of the three trials of the drop-jump
test. The video frames were shot from the midsection down. The video was loaded into analysis
software where the anatomical markers could be
tracked.

•

Height Platform

The height platform was used as part of the dropjump testing. Participants used this platform as
their starting point for each trial. The platform
is 20 inches from the floor and was measured no more
than 15 inches from the force platform during each
trial to reduce forward momentum of the drop-jumps.
•

DartFish ProSuite Version 4.5.1.0
Copyright 2005 DartFish USA, Inc.
Licensed to California University of PA

The DartFish ProSuite software was used in
conjunction with the video recordings of each
participant. This software allowed for slide-byslide 2D video analysis of each trial of the dropjump testing. The selected trial was broken down
and the rectus femoris angles were calculated on the
software during the two crucial frames.

9
•

AMTINetForce Version 2.0
Copyright 1999 Advanced Mechanical Technology, Inc.
176 Waltham St. Watertown, MA 02472-4800

AMTINetForce was a software application that ran the
system for the force platform. Calibration,
platform zeroing and the testing trials were run
through this software. It allowed correction for
body weight, start and stop each trial, and re-run
trials if necessary.
•

Biosoft Version 2.3.0
Copyright 2004 Advanced Mechanical Technology, Inc.
176 Waltham St. Watertown, MA 02472-4800

The Biosoft software program was used in conjunction
with the force platform and AMTINetForce. After
running each trial through AMTINetForce, data was
reconfigured and accessed through Biosoft. Biosoft
provided raw data, graphical analysis and charted
comparison between trials.
•

DELL Latitude D6000 Laptop
Model- PP05L

The Dell Latitude D6000 Laptop was the unit that
stored each software program and was the where all
of the data was uploaded to and saved. Each test
and all of the analysis, along with SPSS statistical
analysis, took place on this unit. All of the data
and analysis has been saved and coded. The files
are all password protected.

10
Procedure

Participants
basis.

were

studied

strictly

on

a

volunteer

Participants were recruited from education programs

as well as through sign-ups available to varsity athletes
at California University of Pennsylvania. All participants
were volunteers with no coercion by faculty, researcher or
superiors, and with no compensation.

Testing Protocol
This study required each participant to complete a brief
warm up, a series of drop to vertical jumps onto a force
platform, and a muscular strength test on a Biodex
isokinetic dynamometer. The warm-up was held in the Human
Performance Lab B5 in Hamer Hall, on the Monark 828E
Ergomedic stationary bicycle where 60 revolutions per
minute with one-kilogram resistance was maintained until
50% of age-predicted maximum heart rate, using Karvonen’s
equation, was achieved. A drop jump test followed the warmup procedure. The procedure for completing the drop-jump
trials was adapted from the protocol created by Frank Noyes
in association with the Cincinnati Sports Medicine and
Orthopedic Center.6 Prior to the test, reflective anatomical
markers were placed bilaterally on a series of bony

11
landmarks (anterior superior iliac spine, superior pole of
the patella, medial and lateral epicondyles of the femur,
medial and lateral malleoli), to assist in data collection
and analysis through a computer biomechanical program.
These markers were referenced as part of the modified
anatomical Helen-Hayes model.7 The researcher demonstrated
the bilateral drop to vertical jump sequence to each
subject, and one practice trial was conducted to ensure
complete understanding of the procedure. The subjects were
not provided with any verbal instruction regarding how to
land or jump, only to land straight on the force platform,
so that the camera would record properly.6 The subjects then
performed the drop to vertical jump sequence by first
jumping off the box, landing bilaterally, and immediately
performing a maximum vertical jump, and then finally
landing back on the force platform. This sequence was
repeated for three trials.

The peak force of each landing

phase and jumping phase was recorded and the trial that
best represented qualitative excellence and highest force
output was selected for analysis. Each force was measured
in Newtons (N).
Each subject was video taped during each of the testing
trials from the anterior view. The main focus in this view
was determining if the knees deviated to a varus or valgus

12
position. Each participant wore anatomical markers so that
the post-analysis could be concluded with less researcher
error.

The same researcher placed each marker.

The video

taped results obtained from the analysis of the jumps of
the participants were analyzed using DartFish ProSuite to
determine if muscular imbalances affected knee angle during
jumping and landing technique. DartFish ProSuite is a 2-D
digital biomechanical analysis program that allows video to
be uploaded and reviewed in stop-motion.

From the anterior

view, two frames were used to determine change in the
rectus femoris angle: (1) land, the frame in which the
subject was at the initial bilateral full-foot landing on
the platform; and (2) takeoff, the frame that demonstrated
the initial forward and upward movement of the arms and the
body as the athlete prepared to perform the maximum
vertical jump.
A muscular strength test, using a Biodex isokinetic
dynamometer,

was

hamstring

concentric

gravity
equipment

to

corrected.
according

conducted

to

quadriceps

Participants
to

the

determine
strength
were

Biodex

concentric
ratios

fitted

Protocol

to

Manual.

nonthe
The

Biodex Dynamometer set-up protocol, which was followed when
testing participants for muscular strength, can be found in
Appendix

C:

Additional

Methods.

Participants

were

tested

13
bilaterally using three speeds of isokinetic movement (120,
180 and 300 degrees per second). A trial period preceded
each testing trial. The trial period allowed the subjects
to become comfortable with the equipment, to reduce any
learning

effect,

and

to

allow

acclimatization

to

the

motions necessary to complete the test. Participants were
required

to

do

repetitions

until:

(1)

the

program

customized for the research test was complete, (2) fatigue
occurred or (3) the test was voluntarily stopped by the
participant with the comfort stop option. Fatigue was based
on

the

perception

of

the

participant

of

the

workload

required. The researcher provided no verbal encouragement
during the trials other than asking that the participants
perform the required knee extension and flexion movements
through the entire range of motion, with as much force and
speed as possible. The results of this test were used to
calculate the hamstrings to quadriceps strength ratio, and
used to determine if strength imbalances were present in
each of the participants.

14
Hypotheses

The following hypotheses were tested:
1. The presence of a muscular strength imbalance
through the H:Q ratio will result in

decreased peak

jump force production.
2. The presence of muscular strength imbalances through
the H:Q ratio will result in an increased drop-jump
landing force.
3. If muscular imbalances are present, an increase in
rectus femoris angle will occur from landing to
jumping phases to compensate for strength
imbalances.

The hypotheses were based on the research literature
reviewed on muscular strength imbalances of the lower
extremities in athletic populations. Additional
investigation will be based on the differences between
muscular imbalance ratio presence and force
production/attenuation.

These differences were based on

the perceptions of previous research found on gender and
athletic status and how these components would play on
strength, coordination, and certain movement patterns.8,9

15

Data Analysis

Statistical significance was assessed using a series
of Pearson Product Moment Correlations.

This equation also

enabled the relationships of terms within the hypotheses to
be viewed. An Independent-sample t-test was used to
determine if H:Q ratio has a relationship with knee angle
(rectus femoris). All statistical tests will be performed
using SPSS 16.0.

16

RESULTS

Demographic Data

The sample that was used in the research study
consisted of 30 physically active individuals.

Each

participant was enrolled as a full-time student at
California University of Pennsylvania and was also
characterized as a legal adult (n > 18 years of age).
Within the sample 53% were males (n=16) and females were
represented by 47% (n=14) of the sample. Each of the
subjects also provided leg dominance. Nearly 93% of
participants reported use of their right leg (n=28) during
kicking and frontal plane balancing, while only 7%
preferred their left leg (n=2).
Table 1 depicts the demographic characteristics of the
participants in this research study.

Table 1. Characteristics of Participants
Demographic
Range
Mean ± SD
Age (yrs.)
18-23
20.73 ± 1.68
___________________________________________________________
Weight (lbs.)
293-110
182.4667 ±
53.8149

17

Table 2 displays the academic rank of participants as
of the semester they participated.

Table 2. Participants’ Class Rank
Academic Rank
Freshman
Sophomore
Junior
Senior
Graduate

Frequency
7
10
5
0
8

Percent
23.3%
33.3%
16.6%
0%
26.7%

Hypothesis Testing

Each of the hypotheses was tested using a confidence
interval of 95%.
Hypothesis 1: The presence of a muscular strength
imbalance through the H:Q ratio will result in

decreased

peak jump force production.
A Pearson Product Moment Correlation was calculated to
determine whether there is a relationship between Bilateral
H:Q Ratio Deviation (H:QDAVG) and the Peak Jump Force (PJF)
during a drop-jump test.

Table 3 shows the results of the

Pearson Product Moment Correlation for Hypothesis 1.

18
Table 3. Pearson Correlation for H:Q Ratio Deviation
Average (H:QDAVG) and Peak Jump Force (PJF)
Variable
H:QDAVG and
PJF
* p < .05
Conclusion:

N
30

r
-.115

P
.545

No correlation was found (r30 = -.115, p >

.05), indicating that no significant relationship exists
between the two variables.

Participants’ peak jump force

was independent of their H:Q ratio.
Hypothesis 2: The presence of muscular strength
imbalances through the H:Q ratio will result in an
increased drop-jump landing force.
A Pearson Product Moment Correlation was calculated to
determine whether there is a relationship between Bilateral
H:Q Ratio Deviation (H:QDAVG) and the Peak Landing Force
(PLF) during a drop-jump test.

Table 4 shows the results

of the Pearson Product Moment Correlation for Hypothesis 2.

Table 4. Pearson Correlation for H:Q Ratio Deviation
Average (H:QDAVG) and Peak Landing Force (PLF)
Variable
H:QDAVG and
PLF
* p < .05

N
30

r
-.263

P
.161

19
Conclusion:

No correlation was found (r30 = -.263, p >

.05), indicating that no significant relationship exists
between the two variables.

Participants’ peak landing

force was independent of their H:Q ratio.
Hypothesis 3: If muscular imbalances are present, an
increase in rectus femoris angle will occur from landing to
jumping phases to compensate for strength imbalances.
An Independent-samples t-test was performed to
determine whether the presence of a muscular imbalance had
an effect on the rectus femoris angle during both the
initial landing and initial jumping phase of the drop-jump
test. The rectus femoris angle was assessed during each
phase on each leg and the absolute value of the Average
Bilateral Change (ABSBIDELTA) between the Landing and
Jumping Phases was recorded. The grouping variables for the
independent-samples were Group 1: Normal Ratio/Muscular
Balance and Group 2: Non-normal ratio/Muscular imbalance.
Normal ratios values were determined as of 60% ± 5%, while
equal variances were assumed. The Group Statistics
detailing the Independent-samples t-test of the Average
Bilateral Change between the Landing and Jumping Phases
(ABSBIDELTA) on Muscular Imbalance Presence is depicted in
Table 5.1.

Table 5.2 shows the results of the Independent-

samples t-test for Hypothesis 3.

20

Table 5.1. Group Statistics of Average Bilateral Change
between the Landing and Jumping Phases (ABSBIDELTA) on
Muscular Imbalance Presence

ABSBIDELTA

Normal Ratio?
Yes:1
No: 2

N
7
23

Mean
16.90
8.24

SD
6.39
1.72

Table 5.2. Independent-sample t-test of Average Bilateral
Change between the Landing and Jumping Phases (ABSBIDELTA)
on Muscular Imbalance Presence

ABSBIDELTA

T
1.642

Sig.(2-tailed)
.112

Mean Dif.
7.58

(equal variances assumed)

* p < .05
Conclusion:

No significance was found (t = 1.642, p >

.05), in the relationship between H:Q values and ∆ average
bilateral rectus femoris angle.

Additional Findings

In addition to the hypotheses testing, a group of
Pearson Correlations was performed to investigate other
independent variables involved in this research study. The
average of the bilateral H:Q ratios was determined and was
used to filter each participant into one of two groups:
Overall Hamstring Driven or Overall Quadriceps Driven.

21
Each group was prepared for analysis through the
aforementioned group of Pearson Correlations.
A Pearson Product Moment Correlation was calculated to
determine if a relationship between the Overall Quadriceps
Driven (AVGOVRDRVN) Group and Peak Jump Force (PJF) exists.
Table 6.1 details the Descriptive Statistics for the
Overall Quadriceps Driven (AVGOVRDRVN) Group on Peak Jump
Force (PJF) Performance. Table 6.2 shows the results of the
Pearson Product Moment Correlation for Overall Quadriceps
Driven (AVGOVRDRVN) Group on Peak Jump Force (PJF)
Performance.

Table 6.1. Descriptive Statistics of Overall Quadriceps
Driven (AVGOVRDRVN) Group on Peak Jump Force (PJF)
Performance

AVGOVRDRVN
PJF (N)

N
5
5

Mean
-8.5133
2231.5940

Std. Dev
9.60036
914.29607

Table 6.2. Pearson Correlation for Overall Quadriceps
Driven (AVGOVRDRVN) Group on Peak Jump Force (PJF)
Performance
Variable
AVGOVRDRVN and
PJF
* p < .05

N
5

r
-.905

P
.035*

22
Conclusion: A significant correlation was supported (r5
= -.905, p < .05), indicating that a significant
relationship exists between the two variables.

Most of the

participants that have been filtered as part of the Overall
Quadriceps Driven Group, had a better performance in their
Peak Jump Force during the drop-jump test.
A Pearson Product Moment Correlation was calculated to
determine if a relationship between the Overall Quadriceps
Driven (AVGOVRDRVN) Group and Peak Landing Force (PLF)
exists. The Descriptive Statistics, Table 7.1, are listed
for the Overall Quadriceps Driven (AVGOVRDRVN) Group on
Peak Landing Force (PLF) Performance. Table 7.2 shows the
results of the Pearson Product Moment Correlation for
Overall Quadriceps Driven (AVGOVRDRVN) Group on Peak
Landing Force (PLF) Performance.

Table 7.1. Descriptive Statistics of Overall Quadriceps
Driven (AVGOVRDRVN) Group on Peak Landing Force (PLF)
Performance

AVGOVRDRVN

N
5

Mean
-8.5133

Std. Dev
9.60036

PLF (N)

5

3998.4766

294.93693

23
Table 7.2. Pearson Correlation for Overall Quadriceps
Driven (AVGOVRDRVN) Group on Peak Landing Force (PLF)
Performance
Variable
AVGOVRDRVN and
PLF
* p < .05

N
5

r
.663

P
.223

Conclusion: No correlation was found (r5 = .663, p >
.05), indicating that no significant relationship exists
between the two variables.

Participants’ peak landing

force was independent of the filtered group of Overall
Quadriceps Driven.
A Pearson Product Moment Correlation was calculated to
determine if a relationship between the Overall Hamstring
Driven (AVGOVRDRVN) Group and Peak Jump Force (PJF) exists.
The Descriptive Statistics of the Overall Hamstring Driven
(AVGOVRDRVN) Group on Peak Jump Force (PJF) Performance is
depicted in Table 8.1. Table 8.2 shows the results of the
Pearson Product Moment Correlation for Overall Hamstring
Driven (AVGOVRDRVN) Group on Peak Jump Force (PJF)
Performance.

24
Table 8.1. Descriptive Statistics of Overall Hamstring
Driven (AVGOVRDRVN) Group on Peak Jump Force (PJF)
Performance

AVGOVRDRVN
PJF (N)

N
25
25

Mean
12.3233
2401.3761

Std. Dev
10.10326
812.92427

Table 8.2. Pearson Correlation for Overall Hamstring Driven
(AVGOVRDRVN) Group on Peak Jump Force (PJF) Performance
Variable
AVGOVRDRVN and
PJF
* p < .05

N
25

r
-.326

P
.112

Conclusion: No correlation was found (r5 = -.326, p >
.05), indicating that no significant relationship exists
between the two variables.

Participants’ peak jump force

was independent of the filtered group of Overall Hamstring
Driven.
A Pearson Product Moment Correlation was calculated to
determine if a relationship between the Overall Hamstring
Driven (AVGOVRDRVN) group and Peak Landing Force (PLF)
exists.

The Descriptive Statistics of the Overall

Hamstring Driven (AVGOVRDRVN) Group on Peak Landing Force
(PLF) Performance is depicted in Table 9.1.

Table 9.2

shows the results of the Pearson Product Moment Correlation
for Overall Hamstring Driven (AVGOVRDRVN) Group on Peak
Landing Force (PLF) Performance.

25

Table 9.1. Descriptive Statistics of Overall Hamstring
Driven (AVGOVRDRVN) Group on Peak Landing Force (PLF)
Performance

AVGOVRDRVN
PLF (N)

N
25
25

Mean
12.3233
3490.6652

Std. Dev
10.10326
487.60783

Table 9.2. Pearson Correlation for Overall Hamstring Driven
(AVGOVRDRVN) Group on Peak Landing Force (PLF) Performance
Variable
AVGOVRDRVN and
PLF
* p < .05

N
25

r
-.162

P
.439

Conclusion: No correlation was found (r5 = -.162, p >
.05), indicating that no significant relationship exists
between the two variables.

Participants’ peak landing

force was independent of the filtered group of Overall
Hamstring Driven.
A Pearson Product Moment Correlation was calculated to
determine if a relationship existed between the Peak
Landing Force (PLF) and Peak Jump Force (PJF) of the
Overall Quadriceps Driven (AVGOVRDRVN) group. Table 10
shows the results of the Pearson Product Moment Correlation
for Overall Quadriceps Driven (AVGOVRDRVN) Group on Peak

26
Landing Force (PLF) Performance vs. Peak Jump Force (PJF)
Performance.

Table 10. Pearson Correlation for Overall Quadriceps Driven
(AVGOVRDRVN) Group on Peak Landing Force (PLF) Performance
vs. Peak Jump Force (PJF) Performance
Variable
PLF and
PJF
* p < .05

N
5

r
-.346

P
.568

Conclusion: No correlation was found (r5 = -.346, p >
.05), indicating that no significant relationship exists
between the two variables in the filtered group.
Participants’ peak landing force and peak jump force were
not significantly related as part of the filtered group of
Overall Quadriceps Driven.
A Pearson Product Moment Correlation was calculated to
determine if a relationship existed between the Peak
Landing Force (PLF) and Peak Jump Force (PJF) of the
Overall Hamstring Driven (AVGOVRDRVN) group. Table 11 shows
the results of the Pearson Product Moment Correlation for
Overall Quadriceps Driven (AVGOVRDRVN) Group on Peak
Landing Force (PLF) Performance vs. Peak Jump Force (PJF)
Performance.

27
Table 11. Pearson Correlation for Overall Hamstring Driven
(AVGOVRDRVN) Group on Peak Landing Force (PLF) Performance
vs. Peak Jump Force (PJF) Performance
Variable
PLF and
PJF
* p < .05

N
25

r
.197

P
.345

Conclusion: No correlation was found (r5 = .197, p >
.05), indicating that no significant relationship exists
between the two variables in the filtered group.
Participants’ peak landing force and peak jump force were
not significantly related as part of the filtered group of
Overall Hamstring Driven.
Additional Numeric Findings from data collection have
been provided to allow for further analysis and
comprehension.

These findings can be viewed in Table 12.

Table 12. Additional Numeric Findings
Variable
Range
Mean ± SD
Peak Landing Force (N)
4508.5-2100.9
3575.3 ± 495.7
________________________________________________________________________
Peak Jump Force (N)
3532.6-1178.1
2373.0 ± 816.3
________________________________________________________________________
Bilat. H:Q Ratio Dev.
40.2-1.6
12.2 ± 9.5
________________________________________________________________________
Bilat. Overall Driven
40.2- -20.9
8.8 ± 12.6
________________________________________________________________________
Bilat. Abs. ∆ knee angle 44.7-1.2
12.7 ± 11.0

28

DISCUSSION

In the discussion section of the research, the
following sections are presented: 1) Discussion of Results,
2) Conclusions on research, and 3) Recommendations.

Discussion of Results

This study focused on the presence of muscular
imbalances and the implications of the H:Q ratio on sport
specific factors, such as landing and jumping forces. In
physical activity of all types, especially those classified
as multi-planar, the ability to react to stimuli (i.e. ball
movement, personnel shift) is an important attribute for a
participant. These multi-planar shifts and moves create
stress on the body and more specifically joints of the
lower extremity. The human body adapts to its environment
and is able to work through these changes and absorb the
forces safely.

Through the bony skeletal and muscular

make-up, the kinetic chain of the human body enables us to
make these moves without a second thought.

If the body

were to break down or be insufficient in a certain area,
then clearly the performance may suffer as well.

Muscular

29
imbalances can lead to serious injury due to over active
musculature (agonist), under active musculature
(antagonist) and the inability of the body to control each
joint in kinesthetic space properly.
The data published on the H:Q ratio states that the
hamstring group has been shown to produce only about 60% of
the torque that is produced by the reciprocal quadriceps
group.2 As illustrated prior, when this percentage is
significantly higher or lower, there can be deficits
throughout performance due to injury, body kinetics and
overall biomechanics. There is a large base of literature
that has been able to make a correlation between muscular
imbalances of the H:Q ratio, change in knee angle during
activity and force production and injuries of the lower
extremity, especially catastrophic injury in the female
4,6,7,8

knee.

The risk of injury, past history with injury and

poor biomechanics can have an affect on sport performance.
The thought process determining the composition of the
first hypothesis is that if a muscular imbalance is
present, in either direction (e.g. + Hamstring driven, Quadriceps driven) a decrease in peak jump force would
result because of poor kinetic chain use, poor kinematics
and inability to transfer force properly for explosive
performance.

Similarly, the second hypothesis which was

30
asking about the H:Q ratio and effect on landing forces was
not found to be significant.

Justification for this

hypothesis showed that inability to control the body and
it’s limbs proprioceptively throughout time and space would
allow for larger forces to act on the body and absorption
to occur less effectively.

No significance was found. So,

what do muscular imbalances have an effect on if not
performance ability and environment awareness?

The third

hypothesis attempted to answer this question by compounding
the results along with the participant’s neuromuscular
control during motion analysis.

No significance was found

when sampling H:Q ratio and change in rectus femoris angle
over time.
There were several additional findings that whether
showing significance or not, have given an interesting
insight into the spectrum of performance enhancement.

A

correlation in the study looked at the relationship of the
peak jump force versus the peak landing force in both
filtered H:Q ratio groups.

Neither group showed any

significance meaning that one’s ability via the peak jump
force had no relationship with that same individual’s
ability with peak landing force.
The goal for this type of data is to once again
quantify an acceptable H:Q ratio for certain populations

31
with general physical activity and to hopefully allow
further research to create safe, acceptable ratios for
several different levels and areas of competition. Is it
safe for athletes that compete in terminal patterns to be
overactive along with primarily vertical athletes? Should
multi-planar athletes be focusing on other aspects of lower
extremity kinematics rather than H:Q ratio?

These are

questions that need further research as athletes and their
participation evolve.

Conclusions

This study demonstrated that the H:Q ratio as measured
with knee flexion/extension has little impact on the
ability to produce maximal vertical force and absorb
landing ground forces.

This study did find however, that

individuals that have a lower H:Q ratio, showing that their
hamstring groups are much weaker than their quadriceps
group, in the allotted ratio, are able to produce more peak
jump force than any other group.

A strong relationship is

shown in that quadriceps driven individuals will produce
more vertical force.

When performing the same correlation

with the hamstring driven group, no significance was
reported, noting that hamstring driven athletes may or may

32
not be able to produce the highest peak jump force. No
relationship was granted for this statistic. In the
opposite correlation where peak landing force was recorded
against the two filtered groups, no significance was cited
in either direction.

One implication that can be drawn

from this data is that if you are training for a
competition that is terminal in direction and the main goal
is to produce the highest peak jump force and highest
vertical jump height, training for a low H:Q ratio would be
beneficial.

The problem with this and why these findings

have little statistical significance in the clinical
setting is that most participation in athletics requires
the multi-planar movement.

In order to accomplish this

effectively and safely, the reciprocal muscles must act in
a respective fashion to allow for proper movement. The fact
that little significance was shown in this research
compounds the questions that we have no answers to in
regards to muscular imbalances and performance.
The most important conclusion that we can take from
this research is that more must be done to further our
knowledge. Few questions have been answered with the
significance found in this research and many more have been
brought up with the lack of relationships cited.

The

current research has provided us with insight to the

33
issues, but as stated earlier as athletes, competition and
performance evolve, the necessity for knowledge to not only
reduce injuries in the clinic but to also prophylactically
prepare athletes for competition at the highest level of
safe performance possible will only help us deepen our
understanding of the underlying issues.

Recommendations

While this study was effective and efficient in its
methods, more advanced technology and analysis is necessary
for further research.

The ability to reproduce data and

have it available to other analysis will only help answer
questions on this issue.

An interesting correlation that

should be looked at is the effect of the H:Q ratio on
different types of athletes as previously mentioned.
Terminal athletes will present differently from multiplanar athletes and their results may help to answer the
individual H:Q ratio concerns.
The data collection performed for this research was
completed throughout the month of April.

Not only were

physically active individuals used, but also full-time
athletes that may have been in-season, pre-season training
or off-season conditioning.

It is important in further

34
research to test multiple times throughout the training
periods to ensure for appropriate acclimatization to
training regimens.
Most previous research regarding the H:Q ratio and
injury has examined gender differences and compared males
and females as part of their statistical testing.

While,

the current researcher is very aware that gender
differences do occur and can lead to staggering differences
in injury rates, this was not the specific focus of this
research. Several studies of gender differences were
referenced throughout this research to provide insight for
the sample as well as general information.

Both genders

were examined as part of this research and tested within
subjects.

Further research should call for continued

testing of gender differences, specifically sport specific
differences.
Difference in population for testing would also be an
imperative tool. Perrin et al2 has published numerous
normative values for different populations however, changes
in populations and participation requires continued
research in these areas.

35
REFERENCES
1.

Murphy, D.F., Connolly, D.A.J., & Beynnon, B.D. Risk
factors for lower extremity injury: a review of the
literature. Bj Sport Med, Retrieved 9/20/2008, from
http://www.bjsm.bmj.com.

2.

Perrin, David H. Isokinetic Exercise and Assessment.
Human Kinetics Publishers, 1993: 2.

3.

Coombs R, Garbutt G. Developments in the use of the
hamstring/quadriceps ratio for the assessment of
muscle balance. Journal of Sports Sciences and
Medicine. 2002; 1: 56-62.

4.

Pappas E, Sheikhzadeh A, Hagins M, Nordin M. The
effect of gender and fatigue on the biomechanics of
bilateral landings from a jump: peak values. Journal
of Sport Science and Medicine, 2007: 6: 77-84.

5.

Whaley, M. H. & Brubaker, P. H. (Eds.) ACSM’s
Guidelines for Exercise Testing and Prescription.
Lippincott Williams & Wilkins, 2006: 7.

6.

Noyes F, Barber-Westin S, Fleckenstein C, Walsh C, &
West J. The drop-jump screening test: Difference in
lower
limb
control
by
gender
and
effect
of
neuromuscular
training
in
female
athletes.
The
American Journal of Sports Medicine, 2005: 33: 197207.

7.

Davis RB, Ounpuu S, Tyburski D, Gage JR. (1991) A Gait
Analysis Data Collection and Reduction Technique.
Human Movement Science, 10: 575-587.

8.

Buchanan PA, Vardaxis VG. Sex-related and age-related
differences in knee strength of basketball players
ages 11-17 years. Journal of Athletic Training. 2003;
38: 231-37.

9.

Russell KA, Palmieri RM, Zinder SM, Ingersoll CD. Sex
differences in valgus knee angle during a single-leg
drop jump. Journal of Athletic Training, 2006: 41:
166-171

36

APPENDICES

37

APPENDIX A
Review of Literature

38
REVIEW OF LITERATURE

The use of strength and conditioning as well as
physical performance enhancement specialists has become an
increasingly new tool in the preparation and training
methods of elite athletes.

Their knowledge and know-how in

the realm of body input and output is necessary to help
prevent injury and to increase athletic performance during
competition.
One issue that plagues athletes, through most of their
skillful movements, is the imbalance of agonist and
antagonist muscles.

Athletic trainers and performance

enhancement specialists are uniquely positioned to assist
athletes with this problem.

Muscular imbalances, which are

difficult to find, can act as a silent menace.

The body

still continues to perform its tasks, including activities
of daily living or competitive movements, although with
much risk to the body.

Early identification and reduction

of these imbalances can reduce the risk of harm during
movement.
Imbalances can lead to a number of physical
compensations such as muscular tightness to increase
mechanical advantage over a joint, increasing the
likelihood of posture misalignment, musculoskeletal

39
injuries and a decrease in athletic performance.1 The
purpose of this literature review will be to discuss the
prevalence of muscular imbalances and their effect on
athletic performance.

The review of literature will be

separated into the following sections: (1) muscular
imbalances, (2) muscular strength, (3) movement patterns,
and (4) anatomical gender differences.

Muscular Imbalances

Muscular strength imbalances result when agonist and
antagonist muscle groups do not have comparable strength
levels. Muscle strength imbalances and the inhibition of
muscle groups can lead to several debilitating injuries,
potential joint instability, and postural misalignments of
the kinetic chain. These limitations can decrease athletic
ability or decrease the ability to complete activities of
daily living in individuals, as well as increase the risk
of injury during these tasks.2,3 Imbalances are theorized to
lead to an increase in injury rates; however, there is
little agreement in the literature to determine which
intrinsic or extrinsic factors may influence muscular
imbalances. There is currently no concrete evidence
determining which factors, such as age, gender, level of

40
competition, leg dominance, or neuromuscular control, may
affect muscular imbalances of the lower extremities.
As a result of muscular imbalances, more attention
needs to be focused on neuromuscular training and
rehabilitation to target a balanced ratio between agonist
and antagonist muscle groups. Previous research has defined
the fact that muscular imbalances can lead to injury and
ultimately decrease performance.

Little research has been

found by the current researcher showing quantitative data
on how a muscular imbalance can affect sport-specific
movements.

It is important to collect this data because

not only will it result in increased knowledge of the topic
data but could help in redefining the accepted hamstring:
quadriceps ratios of certain populations, most closely
researched by Perrin et al6 and Coombs et al4.
The severity of one specific muscular imbalance can be
calculated by measuring an individual’s hamstring to
quadriceps strength ratio (H:Q) by using isokinetic
testing.

Computation of this ratio has come under much

debate because of accuracy concerns as well as its ability
to determine risk of injury as previously indicated.4
Conventional measuring of the H:Q ratio is most commonly
used to measure strength differences; however, “since
opposing muscles are not capable of simultaneous concentric

41
muscle actions, the value of the conventional ratio has
been questioned”.5 A controversial point in H: Q ratio
testing is calculating the “normal” values for each
participant in comparison to a population.

Most research

has indicated that the range or value should be close to
.60.6 This value indicates that the hamstring muscle group
should be able to produce force 60% of what the quadriceps
muscles are able to produce.

The concept of the value of

.60, is to enable researchers to determine if a significant
muscular imbalance is present between the agonist and
antagonist muscle groups of the upper leg.4

Muscular Strength

Muscular strength plays an important role in
functional ambulation, however, “it is unclear whether
muscle contraction, evaluated in terms of strength,
imbalance of extensors relative to flexors, or reaction
time, is a risk factor for injury”.7 Soderman, Alfredson,
and Pietila found a decreased ratio of hamstring to
quadriceps strength to increase the likeliness of incurring
a traumatic leg injury, as well as an increase in overuse
injury in female soccer players.8

42
Barber-Westin, Galloway, Noyes, Corbett and Walsh
performed a study of neuromuscular control on male and
female nine and ten year olds.

Several studies had been

completed prior to this study, but none found significant
results with prepubescent athletes. This study tested
different methodologies, such as drop-jump testing and
single leg hops.

The strength of the quadriceps and

hamstrings were tested isokinetically at 180 degrees/second
on a Biodex dynamometer. The drop jump, single leg hop, and
Biodex dynamometer were chosen to compare between genders
because previous data had found an increase in ligamentous
injury in females (up to 4 to 8 times) as opposed to males
at the adolescent to adult age level. Results showed that
males demonstrated a normal knee and ankle separation on
the drop-jump test. Seventy six percent of males and 90% of
females demonstrated ankle distances of 60% or less of the
hip separation distance, which is indicative of a valgus
alignment. No differences were cited between males and
females in quadriceps/hamstring peak torque,
quadriceps/hamstring ratio, total work, and lower limb
symmetry values after being examined on the Biodex
dynamometer.9
In a similar study, Noyes, Barber-Westin,
Fleckenstein, Walsh and West described and tested a similar

43
methodology as the study completed by Barber-Westin,
Galloway, Noyes, Corbett, and Walsh. Past studies and
research scientists have described “differences between
sexes in neuromuscular indices, such as muscle strength,
running, cutting, sidestepping, and landing
characteristics”.9 The increase in number of non-contact
ligamentous injuries in male and female athletes has
triggered the study of knee alignment during movement
patterns. The reason why the drop-test is an efficient and
effective test to perform as part of methodology is the
fact that it can be visualized from several angles and can
differentiate between alignments of the lower extremity.10
Alignment and biomechanics are necessary to perform at
one’s highest level.

This study was able to point out

valgus, varus, and neutral alignments between male and
female athletes and the correlation that they had with
injury rate.

A valgus or varus alignment with an anterior

load force can lead to knee ligamentous injury.11 Comparable
to Barber-Westin et al., Noyes et al. showed results of
unmarked differences between males and females in the dropjump test.

A valgus alignment was evident in the majority

of the male and female athletes.9,10
According to Noyes et al., few studies have been able
to accurately measure the distance of separation between

44
the hips, knees, and ankles between any of the phases of
landing or take-off of a drop-jump.

This study has

triggered a large interest in methods that will allow
further studies to test in this fashion.10

Movement Patterns

Several researchers have used jumping and landing
phases of the drop jump test as a method to determine
movement pattern characteristics.

The individual must be

observed from three views: anterior, posterior, and
lateral; and must be assessed several times from each
view.12 For the anterior view, the main focus is on
determining if the foot is in normal or toe out position
(toe out defined as when the 2nd metatarsophalangeal joint
rotates outward and appears lateral to the medial
malleolus), as well as if the knee deviates inward instead
of staying in a neutral position. For the lateral view it
is important to assess the trunk and the upper extremities.
For this view, it is important to observe the placement of
the arms, as well as evaluating excessive trunk lean, where
the trunk does not appear to remain parallel with the lower
leg during the descent phase of the squat.

The knee must

also be viewed for tracking over the toes during flexion.

45
During the posterior view, it is important to note if
flattening of the medial longitudinal arch occurs
(longitudinal arch is defined as the curvature of the hind
and mid-foot).13 This type of qualitative analysis has been
used frequently in the research done prior in assessing
neuromuscular control of participants.

This type of

research has led to findings of differences between male
and female control, specific sport control changes and
training adaptations to neuromuscular control.14,15 This
previous data calls for further research into the
introduction of training programs to increase neuromuscular
control in an effort to control catastrophic injuries,
allowing the individuals to adapt to unique situations,
similar to that in geriatric balance or gait training.16
Part of the movement analysis incorporates limb
dominance as well.

The rate of injury, more specifically

non-contact ACL injury, has increased as individuals
increase in sport participation. Factors like field surface
changes and lack of recovery/strengthening period can also
lead to similar injuries of this type.17,18

46
Gender Differences

“Anterior cruciate ligament injury occurs with a 4- to
6-fold greater incidence in female athletes compared with
male athletes playing the same landing and cutting sports.
The elevated risk of ACL injury in women, coupled with the
10-fold increase in high school and 5-fold increase in
collegiate sport participation in the past 30 years, has led
to a rapid rise in ACL injuries in female athletes.”19
Buchanan and Vardaxiz compared both male and female
basketball players to assess hamstring and quadriceps
strength in 11-13 year olds and 15-17 year olds. In order
to conduct this test a Cybex II dynamometer was used to
determine the isokinetic concentric peak torques relative
to the body mass. These basketball players went through six
trials of each leg performing a maximum concentric knee
extension and flexion. The study showed how age and gender
differences affect hamstring and quadriceps strength. When
comparing 15-17 year old males to females, males have a
greater peak torque: body mass ratio than females; where as
11-13 year old males and females have the same peak torque:
body mass ratio. When looking at age differences (15-17
year olds) relative to gender, males were 50-60% stronger
in the quadriceps and hamstrings, whereas females were

47
stronger by 20% in their hamstrings but showed no
difference in quadriceps strength.20
There is significant data describing the rates of ACL
injuries compared to gender and what pre-disposing factors
cause these injuries; however, this only strengthens the
need to continue research of the H:Q ratio and how it can
hinder or ultimately help an individual with injuries and
performance.21,22 A study completed by Newton et al. assessed
the relationship between dominant and non-dominant legs in
14 female Division 1 college softball athletes, as well as
assessed the differences in muscular strength between the
left and right leg.3 The purpose of this study was to
determine functional strength imbalances of the lower
extremities and to investigate possible relationships among
assorted unilateral and bilateral closed kinetic chain
tests and conventional isokinetic dynamometry used to
determine strength imbalances. The participants were tested
using a series of jumping tests and isokinetic testing
using the dynamometer to assess antagonist and agonist
muscle groups. The results found that there were
significant differences when comparing the dominant and
non-dominant legs for all tests, except the average ground
force production during single leg jumps.3 However, no
consistent differences were found in test performance while

48
comparing strength differences between the left and right
leg. These findings could conclude a weight shift or
differential load in the jumping and landing phase of an
individual, possibly predisposing them to further injury.
Other research has found similar findings in that no
significant differences could be cited between dominant and
non-dominant lower limbs of the participants tested.23,24

Conclusion

The necessity for more in-depth and precise research
investigating with the effects of muscular imbalance and
the toll they have on the body is evident.

Increased

injury rates and decreased performance levels are two
things that are proposed to be significantly tied to
muscular imbalances.

Further research in this area could

lead to more breakthroughs in the non-contact ACL area of
study. However, it is fully possible that muscular
imbalances are a factor in these injuries, the possibility
that specific muscular imbalance for specific event or
training may actually be appropriate, once again
challenging the previous research of Perrin et al.6 The
general population has been defined by a certain numerical
value, as have some subsets of athletic populations;

49
however, an extension of this research could ultimately
lead to controlling muscular imbalances to improve
performance through training techniques specific to gender,
age, sport, and deficiency.25,26 The purpose of the current
study is to determine the effects of the H:Q ratio muscular
imbalance of the leg on force production during the jumping
and landing phases of drop-jump testing.

Several areas of

research and extensive knowledge bases are coming together
to help form the current research and allow these findings
to benefit numerous concepts of sport, movement,
biomechanics, and kinematics.

50

APPENDIX B: THE PROBLEM

51
THE PROBLEM

Definition of Terms
The following definitions of terms will be defined for
this study:

1)

Physically active: any individual that participates
in physical activity at least 3 times a week that
raises their heart rate to 50% maximum heart rate
(i.e. intramural or varsity sports, weightlifting,
cardiovascular walking/jogging etc.)

2)

Muscular imbalance: when agonist and antagonist
muscle groups do not have comparable strength
levels. Specifically defined for physically active
non-disabled individuals by Perrin et al. at a .60
value.

This value represents that the hamstring

group has been shown to produce about 60% torque of
what the reciprocal quadriceps group can. An
imbalance is being recorded for any value that falls
out of ± 5% of the ratio (<55% or >65%).

3)

Injured: Currently have any injuries which require
surgical intervention, or injuries which would

52
impede your ability to complete physical tasks that
are required by this study or are not considered
apparently healthy; according to ACSM standards.
Currently have any illnesses (fever, mononucleosis,
pneumonia etc.), which may significantly limit your
ability to perform physical tasks.

4)

College student: any full time student of California
University of Pennsylvania.

5)

Dominant limb: the limb with which an individual
performs kicking motions most frequently or
preferably.

Forward balancing will also occur on

this leg.

6)

Rectus femoris angle: the inside angle of the limb
measured between dissecting lines from anterior
superior iliac spine (ASIS) to superior pole of
patella and superior pole of patella to dome of the
talus, located at the midpoint of the ankle between
the lateral and medial malleoli.

53

Assumptions
The following assumptions were made for the study:
•

Participants were cooperative while completing the
informed consent and general medical history form,
and were truthful with their answers.

•

Participants fully understood the outlined
parameters, which were used to classify
participation, and were honest with their answers.

•

Participants performed the Biodex Dynamometer
strength test and drop-vertical jump test to the
best of their ability.

•

The Biodex dynamometer for each participant was
appropriately fitted to use the equipment, as well
as a clear explanation of the test was offered.

•

The drop-vertical jump test was clearly explained
and all questions were answered so that the
participants could perform effectively.

•

Instrumentation has been calibrated and is in proper
working order to ensure accurate data collection.

•

All participants are volunteers with no coercion by
faculty, researcher or superiors, with no
compensation.

54
Limitations
The results of this study may be limited by the following:
•

The participation rate of California University of
Pennsylvania students

•

Male and female participant ratios

•

Equal representation of members from each gender to
adequately display the population.

•

Individuals’ pre-disposed anatomical abnormalities,
which may result in less skillful movement patterns
independent of technique, strength, or flexibility.

•

2D video analysis may not be the most accurate or
efficient tool in recording and reviewing movements
of drop-vertical jump testing.

•

Subjects may have varying experience with maximal
jumping and drop jump methodology.

•

Examination of the biomechanical video analysis and
data from the force platform may be inexact.

Delimitations
This study will be delimited by:
•

Only full-time students of California University of
Pennsylvania will participate in the study.

•

Participants must be classified as physically active
in order to continue in the research.

55
•

Participants must not have received any injuries
that significantly altered their physical activity
or health status within one calendar year.

Significance of the Study
This study holds several practical and clinical
implications and for these reasons the research is being
performed.

Muscular imbalances cause injury, as seen in

previous research; however, their effect upon quantitative
performance has not seen significant research performed. It
is necessary to re-evaluate the normal values of H:Q ratio
as applies to different populations and determine if
muscular imbalances if controlled can be beneficial to the
physically active population. This data could lead to a new
quantitative definition of the H:Q ratio and therefore
could lead sports medicine professionals and athletes to
potentially train for a specific H:Q ratio to increase
functional performance.

56

APPENDIX C: ADDITIONAL METHODS

57
Setup and Positioning
1. Seat participant on chair.
2. Rotate chair to 90 degrees.
3. Rotate dynamometer to 90 degrees. Slide dynamometer
along travel to position outside leg to be tested or
exercised.
4. Attach knee attachment to dynamometer. Align dynamometer
shaft red dot with red dot on attachment.
5. Move participant into position.
6. Align participant knee axis of rotation with dynamometer
shaft. Raise/lower seat or move participant toward/away
from dynamometer to fine adjust.
7. Adjust knee attachment so that it is proximal to medial
malleoli. Secure with strap.
NOTE: Moving the pad proximally has been demonstrated to
decrease anterior tibular translation.
8. Stabilize participant with shoulder, waist and
thigh straps.
9. Set range of motion (ROM) stops.
Opposite Side
1. Unstrap participant’s knee from attachment and thigh
strap.
2. With participant remaining in chair, slide chair back
away from dynamometer.
3. Press Hold button to retain dynamometer shaft position.
Remove attachment. Get knee attachment for opposite side.
4. Rotate dynamometer to 90 degrees on opposite side. Slide
dynamometer to opposite side of patient.
5. Attach knee attachment to dynamometer. Align dynamometer
shaft red dot with red dot on attachment.
6. Move participant into position.

58
7. Align participant knee axis of rotation with dynamometer
shaft. Raise/lower seat or move participant toward/away
from dynamometer to fine adjust.
8. Adjust knee attachment so that it is proximal to medial
malleoli. Secure with strap.
9. Stabilize participant with shoulder, waist and thigh
straps.
10. Reset ROM stops.

59

Table 1.

Coronary Artery Disease Risk Factors Thresholds

Risk Factors: (Positive)
Family History

Defining Criteria
Myocardial infarction, coronary
revascularization, or sudden
death before 55 years of age in
father or other male first-degree
relative (i.e., brother or son),
or before 65 years of age in
mother or other female firstdegree relative (i.e., sister or
daughter)

Cigarette Smoking

Current cigarette smoker or those
who quit within the previous 6
months.

Hypertension

Systolic blood pressure of ≥140
mm Hg or diastolic ≥90 mm Hg,
confirmed by measurements on at
least 2 separate occasions, or on
antihypertensive medication.

Hypercholesterolemia

Total serum cholesterol of >200
mg/dl (5.2 mmol/L) or highdensity lipoprotein cholesterol
of <35 mg/dL (0.9 mmol/L), or on
lipid-lowering medication. If
low-density lipoprotein
cholesterol is available, use
>130 mg/dL (3.4 mmol/L) rather
than total cholesterol of >200
mg/dL.

Impaired Fasting Glucose

Fasting blood glucose of ≥110
mg/dL (6.1 mmol/L) confirmed by
measurements on at least 2
separate occasions

Obesity

Body Mass Index of ≥30 mg/m, or
waist girth of >100 cm (≈39.4
inches).

60
Sedentary Lifestyle

Persons not participating in a
regular exercise program or
meeting the minimal physical
activity recommendations from the
U.S. Surgeon Generals’ Report.

Whaley, M. H. & Brubaker, P. H. (Eds.) ACSM’s Guidelines for Exercise Testing and
Prescription. Lippincott Williams & Wilkins, 2006: 7.

ACSM Risk Stratification Categories
1. Low risk: Men <45 years of age and women <55
years of age who are without symptoms and meet no
more than one risk factor threshold.
2. Moderate risk: Men ≥45 years and women ≥55 years
or those who meet the threshold for two or more
risk factors.
3. High risk: Individuals with one or more signs
and symptoms or known cardiovascular, pulmonary, or
metabolic disease.
Whaley, M. H. & Brubaker, P. H. (Eds.) ACSM’s
Guidelines for Exercise Testing and Prescription.
Lippincott Williams & Wilkins, 2006: 7.

61
Informed-Consent Form

1. James Daley, a graduate assistant athletic training
student and Master’s degree candidate, has requested
my participation in a research study at California
University of Pennsylvania. The title of the research
is: A correlation between muscular imbalances of the
lower extremity (H:Q ratio) and force production.
2. I have been informed that the purpose of the research
is to examine the relationship between muscular
imbalances determined by the measured Hamstring:
Quadriceps ratio and their effect on force production
during phrases of a drop-jump test. I understand that
I have been asked to participate, along with 29 other
participants because I am operationally defined as
“physically active”. A “physically active” person is
defined as one that participates in physical activity
raising heart rate to at least 50% maximum (i.e.
cardiovascular training, weight lifting, athletics) at
least 3 times per week on average. I am also allowed
to participate in this research study because I have
not suffered any long term or debilitating previous
injury to my lower extremities, I am of good general
health, I do not know of any personal medical reason
that would prevent me from participating, I am legally
an adult and I am currently a full-time student at
California University of Pennsylvania. I understand
that my participation is strictly on a volunteer
basis, with no coercion by faculty, researcher or
superiors.
3. My participation will involve a physical warm-up on a
stationary bicycle to 50% of my maximum age-adjusted
heart rate, a drop-jump/vertical jump test onto a
force platform, and a muscular strength test utilizing
the Biodex Isokinetic Dynamometer. Each test will
include a trial practice period and 3 testing trials.
My participation in this study will consist of one
testing period equaling no more than 120 minutes. I
will be asked to wear fitting shorts that do not cover
my knees, to tuck in my shirt and to wear athletic
shoes. I understand that prior to the test, reflective
anatomical markers will be placed on both my hips and
lower extremities, on a series of bony landmarks

62
(anterior superior iliac spine, superior pole of the
patella, medial and lateral epicondyles of the femur,
and medial and later malleoli). The researcher will
videotape each participant and the video will be used
in a video biomechanical analysis. The anatomical
markers are necessary to assist in the data collection
for this analysis.
4. I understand there are foreseeable risks or
discomforts to me if I agree to participate in the
study. The possible risks and/or discomforts include
injury/re-injury, mild muscle soreness/discomfort,
feelings of fatigue, and/or possible systemic
complications (myocardial infarction, cardiac failure,
etc.) Risks and discomforts can result from all three
exercises. Muscle fatigue, soreness and/or systemic
complications can result from the warm-up protocol.
Injury/re-injury, mild muscle soreness/discomfort,
feelings of fatigue, and/or possible systemic
complications can result from the muscular strength
testing including muscular strain, total muscular
failure and muscular spasm. The drop-jump/vertical
jump test could result in injury to the lower
extremity, as well as the back or upper extremity
product of a fall. Muscular discomfort and general
fatigue may also result. However, these risks will be
minimized in the following ways: I am required to
complete a general information and eligibility form, a
modified physical activity readiness questionnaire, a
supervised warm up prior to physical activity, and am
responsible to inform the researchers of any abnormal
responses during the physical activity so that the
test may be terminated. I understand that these risks
are reasonable because they will allow for research
into an area of study not completely satisfied. There
are minimal risks associated with this study that are
different from risks involved in regular physical
activity or activities of daily living.
5. I understand that in case of injury I can expect to
receive emergency treatment and first aid care from
the primary researcher, James Daley. The researcher
is First Aid, AED, and CPR certified. Additional
services needed for prolonged care past 3 days will be
referred to the attending physician at the Student
Health Services located in the Wellness Center –

63
Carter Hall (724 938 4232) located at California
University of Pennsylvania.
6. There are no feasible alternative procedures available
for this study.
7. I understand that the possible benefits of my
participation in the research are the increased
knowledge of musculature of the lower extremities.
This knowledge may help improve performance, correct
faulty movement patterns, and decrease the likeliness
of sustaining an injury. The research results may
also lead to a better qualitative and quantitative
definition of a muscular imbalance. These results,
paired with further research, may help to further
improve corrective training techniques used to
decrease injury in susceptible populations. The
information gathered from the results of this research
study could potentially impact the Exercise and Sport
Sciences field, because no conclusive data has been
determined to accurately measure how muscle imbalances
affect quantitative athletic performance.
8. I understand that the results of the research study
may be published but that my name or identity will not
be revealed. In order to maintain confidentiality of
my records, James Daley will maintain all documents in
a secure location in which only the student researcher
and research advisor can access. Any information
obtained during this study that could identify you
will be kept strictly confidential, and any
information will be coded numerically based on
demographic information. This information may be
published in professional (or scientific) journals or
presented at professional meetings, but your identity
will be kept strictly confidential. I am aware that
each trial of each physical test will be recorded on
videotape for the sole purpose of continued data
analysis for this study. The tape will be locked and
stored in the locked private residence of the
researcher. Upon data transfer to the computer, each
video segment will be saved on a laptop which is
password protected, which will be stored in a locked
office adjacent to the Human Performance Lab B5 in
Hamer Hall. As a participant, you have the right to
view the video segments you completed, and also have
the right to refuse permission to use the video

64
segments for any other use besides the educational
purposes of this project. Any additional information
obtained from this study will be stored in the locked
private residence of the researcher. The data will be
used to assess muscular imbalances and movement
patterns, and upon the completion of this project the
data will be stored in a locked location and destroyed
within one year of the completion of this project.
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
James Daley, DAL3467@cup.edu, 532 Third Street
California, PA 15419, (401) 378-8433 and/or Dr. Edwin
Zuchelkowski, Zuchelkowski@cup.edu, 250 University Ave/
Frich Hall 406 California, PA 15419, (724) 938-4202.
11.
I understand that written responses may be used
in quotations for publication but my identity will remain
anonymous.
I have read the above information. 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 waving any legal claims, rights, or remedies. A copy
of this consent form will be given to me upon request.
Subject’s Signature

____________

Other signature (if appropriate)

____________________________

Date
Date

I certify that I have explained to the above individual
the nature and purpose, the potential benefits, and
possible risks associated with participation in this
research study, have answered any questions that have
been raised, and have witnessed the above signature.

65
I have provided the subject/participant a copy of this
signed consent document if requested.
Investigator’s signature

____________________________________________Date___________

Approved by the California University of Pennsylvania IRB
This approval is effective (2/17/2009) and expires on
(2/16/2010).

66

Name of Investigator:
James Daley
Faculty/ Staff Sponsor:
Edwin Zuchelkowski, Ph.D.

Phone:
(401) 378-8433

Email:
DAL3467@cup.edu
Zuchelkowski@cup.edu

INFORMED CONSENT
Title of project: A correlation between muscular imbalances of the lower extremity (H:Q ratio)
and force production
Invitation to Participate: You are invited to participate in this research study. The following
information is provided to help you make an informed decision whether or not to participate. If
you have any questions, please do not hesitate to ask.
Purpose: The purpose of the current research is to examine the relationship between muscular
imbalances and their effect on force production during phases of a drop-jump test.
Subjects:
You are eligible to participate because you are:
1. Over 18 years of age.
2. Of good general health, with no major or long term debilitative injuries to the lower
extremities.
3. A “physically active” person is defined as one that participates in physical activity raising
heart rate to at least 50% maximum (i.e. cardiovascular training, weight lifting, athletics)
at least 3 times per week on average.
4. A full time student at California University of Pennsylvania.
You are not eligible to participate in this study if:
1. You currently do not categorize yourself as “physically active” as defined as you do not
participate in physical activity (i.e. cardiovascular training, weight lifting, athletics) on
average at least 3 times per week.
2. You currently have any injuries, which require surgical intervention, or injuries that
would impede your ability to complete physical tasks that are required by this study.
3. You currently have any illnesses (fever, mononucleosis, pneumonia etc.), which may
significantly limit your ability to perform physical tasks.
Procedures:
If you decide to participate in this research project, you will be asked to complete the following
physical tasks:
• Participants will be asked to wear fitting shorts that do not cover the knee and athletic
shoes preferably low cut. Participants will also be asked to tuck in their shirt to allow for
visual of the anatomical markers by the camera and researcher.

67
•

•

•

•

A brief warm-up will be held in Hamer Hall on a stationary upright bicycle where 60
revolutions per minute with one kilogram of resistance must be maintained until 50% of
maximum heart rate, calculated through Karvonen’s formula, is achieved.
A measurement of concentric hamstrings and concentric quadriceps strength using the
Biodex equipment will be performed. This is a device that measures the strength of
opposing muscle groups by completing the same movement at the same angular velocity
throughout the testing session (similar to fully extending your leg like a kick, and then
pulling your leg back against resistance). Three testing trials will be performed.
A measurement of force production and force attenuation using a series of drop-jump
tests will be performed. Prior to the test, reflective anatomical markers will be placed
bilaterally on a series of bony landmarks (anterior superior iliac spine, superior pole of
the patella, medial and lateral epicondyles of the femur, medial and later malleoli), to
assist in data collection through a computer biomechanical analysis. The drop-jump will
require the participants to jump from a minimal height and land on a force platform. The
participants will then subsequently perform a maximal vertical jump. Three testing trials
will be performed.
All testing measurements will allow for a practice trial period prior to the testing trials to
adjust for learning effect.

Some of these physical tests will be recorded on videotape, and the tape will be locked and stored
in the private residence of the researcher. Upon data transfer to the computer, each video segment
will be saved on a laptop which is password protected, which will be stored in a locked office
adjacent to the Human Performance Lab B5 in Hamer Hall. Only the researcher and the faculty
representative will have access to this data. As a participant, you have the right to view the video
segments you completed, and also have the right to refuse permission to use the video segments
for any other use besides the educational purposes of this project. Any additional information
obtained from this study will be stored in the locked private residence of the researcher. The data
will be used to assess muscular imbalances and movement patterns, and upon the completion of
this project the data will be stored in a locked location and destroyed within one year of the
completion of this project.
Alternatives:
No alternative procedures are available to complete the physical tasks as outlined above. If you
are unable to complete any of the tasks, you will be excluded from this study.
Timetable:
Participation in this study will warrant one individual meeting per participant with the
investigators, which will approximately last for a maximum 120 minutes that will be scheduled
after IRB approval.
Risks:
Whenever one participates in physical activity, there are inherent risks. For the tests in this study,
physical risks that may occur due to the completion of this study are the potential for
injury/reinjury, mild muscle soreness/discomfort, and feelings of fatigue. However, these risks
will be minimized in the following ways:
1. You will complete a general information and eligibility form as well as a modified PARQ form
2. You will complete a supervised warm up prior to physical activity
3. There will be a researcher present for all physical activity.
• The researcher is First Aid, AED, and CPR certified.
o An AED is available on site (1st floor Hamer Hall) if necessary.

68
Physical activity will occur in Hamer Hall, where there is easy access to a phone
to activate an emergency action plan if necessary.
4. You will be informed of your responsibility to inform the researchers of any abnormal
responses during the physical activity so that the test may be terminated.
5. You are encouraged to contact Student Health Services located in the Wellness Center –
Carter Hall (724 938 4232) located at California University of Pennsylvania if there are
any delayed adverse physical responses to the testing protocols.
•

Benefits:
Benefits that will be expected for participants are the increased knowledge of musculature of their
lower extremities. This knowledge may help improve performance, correct faulty movement
patterns, and decrease the likeliness of sustaining an injury. The information gathered from the
results of this research study could potentially impact the Exercise and Sport Sciences field,
because no conclusive data has been determined to accurately measure how muscle imbalances
affect quantitative athletic performance.
Compensation for Participation:
There is no compensation for participation in this study.
Confidentiality:
Any information obtained during this study that could identify you will be kept strictly
confidential, and any information will be coded numerically based on class, gender, and athletic
status. This information may be published in professional (or scientific) journals or presented at
professional meetings, but your identity will be kept strictly confidential.
Right to Refuse or Withdraw:
You may refuse to participate and still receive the care you would receive if you were not in the
study. You may change your mind about being in the study and quit after the study has started.
If the study design or use of the data is changed, you will be informed and your consent will be
obtained for the revised research study.
Questions:
If you have any questions at this time, please ask them. If you have additional questions later,
please contact the investigator or faculty/staff by using the above listed phone number or email
addresses, and we will be happy to answer them.

Your signature below indicates that you have voluntarily decided to participate in this
research project as a subject and that you have read and understand the information
provided above.
___________________________________________
Subject's signature

________________________
Date

___________________________________________
Subject's printed name
My signature as witness certifies that the subject voluntarily signed this consent form in my
presence. (required only for research with greater than minimal risk)

69

______________________________________
Witness signature

_______________________________
Date

___________________________________________
Witness’ printed name
In my judgment, the subject is voluntarily and knowingly giving informed consent to participate
in this research study.
_________________________________________ ____________________________
Investigator's signature
Date
_______________________________________ ______________________________
Investigator's printed name
Date

70
GENERAL INFORMATION AND ELGIBLITY
PLEASE DO NOT WRITE YOUR NAME ON THIS FORM
Please circle:

Female

Current Class Level:

or

Male

Freshman

Sophomore

Junior

Senior

Graduate

Please read the following to determine your eligibility for this study, if at any time you have
any questions in regards to any of the material please do not hesitate to ask the investigator.
You are eligible to participate because you are:
1. Over 18 years of age.
2. Of good general health, with no major or long term debilitative injuries to the lower
extremities.
3. A “physically active” person defined as that you participate in physical activity (i.e.
cardiovascular training, weight lifting, athletics) on average at least 3 times per
week.
4. You are a full time student at California University of Pennsylvania.
You are not eligible to participate in this study if:
1. You currently do not categorize yourself as “physically active” as defined as you do
no participate in physical activity (i.e. cardiovascular training, weight lifting,
athletics) on average at least 3 times per week.
2. You currently have any injuries, which require surgical intervention, or injuries, which
would impede your ability to complete physical tasks that are required by this study.
3. You currently have any illnesses (fever, mononucleosis, pneumonia etc.), which may
significantly limit your ability to perform physical tasks.

71
MODIFIED PAR-Q FORM
Please circle the appropriate response.
If you answer yes to any of the following questions, please discontinue filling out this form as you
will be unable to participate in this study.
Have you suffered any significant injury to the lower extremities in the past four weeks that may
limit physical activity?
Yes or No
Have you had any lower extremity surgeries in the past year?
Yes or No
Has your doctor ever said you have a heart condition and that you should only do physical
activity recommended by a doctor?
Yes or No
Do you feel pain in your chest during physical activity or at rest?
Yes or No
Do you lose your balance because of dizziness or do you ever lose consciousness?
Yes or No
Has a doctor ever said your blood pressure was too high?
Yes or No
Are you currently taking any medications that may hinder participation in short bursts of physical
activity?
Yes or No
Do you have any joint or bone problems that will not allow you to exercise or may be aggravated
by participating in physical activity?
Yes or No
Is there a good physical reason, not mentioned here, why you should not follow an activity
program even if you wanted to?
Yes or No

72

Please note that if your health changes within the time of completing this form and the date
of participation, please notify the investigator.
I have read, understood and completed this questionnaire to the best of my knowledge.

_________________________________________ ____________________________
Participant’s signature
Date
_______________________________________ ______________________________
Participants’ printed name
Date
_________________________________________ ____________________________
Witness signature
Date
_______________________________________ ______________________________
Witness’ printed name
Date

73

74

75

76

77

78

79

80
REFERENCES

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2.

Rosene JM, Fogarty TD, Mahaffey BL. Isokinetic
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3.

Newton, R.U., Gerber, A., Nimphius, S., Shim, J.,
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4.

Coombs R, Garbutt G. Developments in the use of the
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5.

Holcomb, W.R., & Rubley, M.D., Lee, H.J., Guadagnoli,
M.A. Effect of hamstring-emphasized resistance
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21: 41-47.

6.

Perrin, David H. Isokinetic Exercise and Assessment.
Human Kinetics Publishers, 1993: 2.

7.

Murphy, D.F., Connolly, D.A.J., & Beynnon, B.D. Risk
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literature. Bj Sport Med, Retrieved 9/20/2008, from
http://www.bjsm.bmj.com.

8.

Soderman, K, Alfredson, H, & Pietila, T (2001). Risk
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Barber-Westin S., Galloway M, Noyes F, Corbett G, &
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control in prepubescent athletes. The American Journal
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Noyes F, Barber-Westin S, Fleckenstein C, Walsh C, &
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American Journal of Sports Medicine, 2005: 33: 197207.

11.

Russell KA, Palmieri RM, Zinder SM, Ingersoll CD. Sex
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Onate JA, Guskiewicz KM, Marshall SW, Giuliani C, Yu
B, Garrett WE. Instruction of jump-landing technique
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13.

Hirth, C.J. Clinical movement analysis to identify
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Holm I, Vollestad N. Significant effect of gender on
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83
ABSTRACT
Title:

A CORRELATION BETWEEN MUSCULAR
IMBALANCES OF THE LOWER EXTREMITY (H:Q
RATIO) AND FORCE PRODUCTION

Researcher:

James T. Daley

Advisor:

Dr. Edwin Zuchelkowski

Date:

May 2009

Research Type:

Master’s Thesis

Purpose:

The purpose of the current research is
to examine the relationship between
muscular imbalances and their effect on
force production during a drop-jump
test.

Problem:

The question proposed of this study is
whether or not muscular imbalances have
a significant effect on force
production of the lower extremity.
Imbalances can lead to a number of
physical compensations such as muscular
tightness to increase mechanical
advantage over a joint, increasing the
likelihood of posture misalignment,
musculoskeletal injuries. There is
currently no concrete evidence
determining which factors, such as age,
gender, level of competition, leg
dominance, or neuromuscular control,
may affect muscular imbalances of the
lower extremities.

Method:

The research was conducted utilizing a
cross-sectional observational, within
subjects design. Relationships were
assessed between participants based
upon presence of muscular imbalance,
landing force production, vertical
jumping force production and change in
rectus femoris knee angle. Each of the
hypotheses was tested using a
confidence interval of 95%. The

84
subjects (n=30) consisted of a
convenience sample of physically active
full-time students from California
University of Pennsylvania. 16 males
and 14 females were tested as part of
this sample. They performed an
appropriate warm-up of 50% maximum HR
prior to testing. Three trials of a
drop-jump test were performed from a
height platform (20 in.) onto a force
platform. Three trials of varying
speeds (120, 180 and 300 deg./sec.)
were performed bilaterally on the
Biodex dynamometer.
Findings:

No significant difference was found for
the presence of muscular imbalances on
peak landing force or peak jump force.
The presence of a muscular imbalance
also did not exhibit a significant
relationship with the change in rectus
femoris angle between landing and takeoff phase of a drop-jump test.
Participants that were characterized as
part of the Quadriceps Dominant Driven
Group did exhibit a significant
correlation to Peak Jump Force.

Conclusion:

The presence of a muscular imbalance
through the H:Q ratio does not show to
have any significance in the role of
force production or absorption during
functional sport specific loading and
unloading on the lower extremity.
Research must continue to focus on the
effects of muscular imbalances of the
H:Q ratio and how they are
quantitatively manipulating physically
active individuals. Further
recommendations are being made to
research sport and position specific
differences of lower leg function
during activity.