A DESCRIPTIVE EVALUATION OF TWO RECOVERY METHODS ON PHYSIOLOGICAL AND
PERFORMANCE FACTORS IN NCAA DIVISION II BASEBALL PITCHERS

By

John P. O’Grady, B.S.
East Stroudsburg University of Pennsylvania

A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of
Master of Science in Exercise Science to the office of Graduate and Extended
Studies of East Stroudsburg University of Pennsylvania

May 8, 2020

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ABSTRACT
A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of
Master of Science in Exercise Science to the Office of Graduate and Extended
Studies of East Stroudsburg University of Pennsylvania.
Student’s Name: John P. O’Grady
Title: A Descriptive Evaluation of Two Recovery Methods on Physiological and
Performance Factors in NCAA Division II Baseball Pitchers
Date of Graduation: May 8, 2020
Thesis Chair: Shala Davis, Ph.D.
Thesis Member: Brandon Snyder, M.S.
Thesis Member: Matthew Miltenberger, Ph.D.
Abstract
Introduction: Injury rates in all levels of baseball pitchers have increased
over the last two decades, while the knowledge behind the mechanics of
pitching has increased as well. In-game recovery techniques have often been
overlooked as possible methods of maintaining pitching performance, reducing
injury, and decreasing fatigue. Purpose: The purpose of this study was to
investigate the effects of two recovery methods on pitching performance in
male NCAA division II baseball pitchers. Methods: Five male subjects on the East
Stroudsburg University of Pennsylvania’s pitching staff participated in 2
separate simulated bullpen sessions, where sessions were 7 days apart from one
another. Recovery intervention consisting of Passive Recovery (PR) or Electrical
Muscle Stimulation (EMS) occurred after the first 15 pitches. Velocity, spin rate,
and release height were measured by the Rapsodo 2.0 Pitch Tracker. Results:
Descriptive statistics showed EMS better maintained mean velocity over 2
innings of pitching when compared to PR. The results demonstrated that a
greater number of subjects and innings thrown would be necessary to show
significance between recovery methods and pitching measurables. Conclusion:
In conclusion, no definitive recovery method was shown to be favorable over
another.

TABLE OF CONTENTS
List of Figures………………………………………………………………………………………………………………vi
List of Tables……………………………………………………………………………………………………………...vii
CHAPTER
1. INTRODUCTION…………………………………………………………………………………………………1
Purpose…………………………………………………………………………………………………………….4
Delimitations…………………………………………………………………………………………………….4
Limitations………………………………………………………………………………………………………..4
Operational Definitions……………………………………………………………………………………..4
Summary…………………………………………………………………………………………………………..5
2. LITERATURE REVIEW………………………………………………………………………………………...7
Biomechanics of the throwing motion……………………………………………………………...7
Spin Rate………………………………………………………..…………………………………………….…..8
Increases in Injuries and Practical Assessments.…………………………………………….…10
Electrical Muscle Stimulation……….…………………………………………………………………..13
Passive Recovery……..……………………………………………………………………………………….14
Research on Recovery Methods……………………………………………………………………....15
3. METHODOLOGY……………………………………………………………………………………………....17
Subjects…………………………………………………………………………………………………………...17
Procedures……………..……………………………………………………………………………………..…18
Data Analysis………………………………………………………………………………………………..…..21
4. RESULTS……………………………………………………………………………………………………..…...22
5. DISCUSSION……………………………………………………………………………………………………..29
Future Recommendations..……………………………………………………………………………...33
Conclusion………………………………………………………………………………………………………..35
APPENDICES…………………………………………………………………………………………………………………36
iv

APPENDIX A IRB Form…………………………………………………………………………………….…36
APPENDIX B Informed Consent Form……………………………..…………………………………37
APPENDIX C PAR-Q……………………………………………………………………………………………40
APPENDIX D Borg RPE Scale………………………………………………………………………………41
REFERENCES……………………………………………………………………………………………………..42

v

LIST OF FIGURES
Figure
1.

Figure 1. Mean Fastball Velocity Pre and Post Recovery……………………………..23

2.

Figure 2. Mean Spin Rate Pre and Post Recovery………………………………………..24

3.

Figure 3. Mean Release Height Pre and Post Recovery………………………………..25

4.

Figure 4. Mean Overall and Local RPE Compared to Recovery Methods……..25

5.

Figure 5. Mean Heart Rate Pre-Recovery vs Post-Recovery…………………………26

6.

Figure 6. Mean PR and EMS HLa Concentrations…………………………………………27

vi

LIST OF TABLES
Table
1. Table 1. Subject Demographics…………………………………………………………………………18
2. Table 2. Fastball Pitch Totals and Differences in Accuracy Across Recovery
Methods…………………………………………………………………………………………………………..23
3. Table 3. 1-RM Squat Compared to Highest Fastball Velocity…………………………….27

vii

CHAPTER 1: INTRODUCTION

In baseball, just like any sport, the need for bigger, stronger, and faster athletes
continually grows year in and year out. Over the past few decades, Major League
Baseball (MLB) has seen a steady increase in average throwing velocity from pitchers,
while consequently seeing an increase in elbow and shoulder injuries (Wilson et al.,
2015). There have been many methods that are said to contribute to the increase in
injuries, but no one factor has proven to be the root cause. Despite many advances in
the analysis of throwing mechanics using biomechanical approaches i.e. 2-D and 3-D
frame by frame analysis, injury rates rise year after year. Multiple areas of injury
prevention have been examined, such as the use of radar guns in youth and adolescent
facilities/games, exceeding pitch count restrictions, increases in off-speed pitches
thrown, and sport specificity. Although a combination of the aforementioned methods
may elicit injury, few studies have looked at in-game recovery methods to
prevent/monitor injuries in all levels of pitchers. Because of the nature of a baseball
game, pitchers can have an undetermined amount of rest in-between innings which
makes it difficult to prescribe appropriate recovery methods in-game.
1

During competition, pitchers use an explosive delivery to generate the necessary
speed/spin on each pitch to ultimately get the batter they are facing out. This motion
needs to be repeated each pitch, with an undetermined amount of pitches that can be
thrown each inning. At certain points during a game, a pitcher may need to produce
maximal force/velocity in their motion to induce an out. A pitcher’s level of physical
strength/conditioning may be one of the determining factors on the speed of a pitcher’s
maximal velocity pitch. One measure of maximal force that may correlate to maximal
velocity is the 1-Repetition Maximum (1-RM) Back Squat. With the obvious importance
of lower body involvement/force development during the pitching delivery, pitchers
with larger 1-RM back squats may be able to throw at higher velocities.
Anaerobic and ballistic in nature, the pitching delivery can cause muscular
fatigue and a loss of control while the number of pitches thrown increases (Hackney,
1996). As the anaerobic system depletes without proper rest, the aerobic system
becomes the main source of energy for a pitcher. As this occurs pyruvate is converted to
blood lactate (HLa) and these concentrations rise in the bloodstream. Because elevated
HLa levels are closely associated with muscular fatigue, a pitcher’s performance in-game
could decline rapidly if HLa levels stay elevated. Once a pitcher can rest between innings
or batters, their body is able to clear lactate because the demand for immediate energy
is low and oxygen is shuttled to working musculature. Different recovery protocols have
been examined to see which is more efficient in clearing HLa at rest for baseball

2

pitcher’s in-between innings, but HLa levels have not been recorded at high enough
levels to induce muscular fatigue (Warren, Szymanski, & Landers, 2015).
Two researched recovery methods for pitcher’s in-between innings include
passive recovery (PR) and electrical muscle stimulation (EMS). PR is a strategy commonly
used in recovery for baseball pitchers at all levels of competition. PR is when a pitcher
sits down between innings and wears a jacket either around their arm or on their body.
A study by Monedero (2000) showed a decrease in HLa concentrations after a maximal
incremental cycling protocol followed by 15 minutes of passive recovery. Although
shown to be efficient with substantial rest, most pitchers will not have 15 minutes of
time for rest between innings for HLa levels to return to resting. The EMS recovery
method has not been examined as extensively as PR for in-game recovery for pitchers.
EMS has been used frequently in rehabilitation processes for post-operative individuals,
and for muscular repair. The theory behind EMS is that EMS induces muscle
contractions through generating action potentials via external electrical stimulus; this
process induces blood flow to working musculature and helps to clear lactate build up
after strenuous exercise. As lactate is cleared during recovery, a subject may be able to
compete for longer durations due to less built up fatigue. Determining which recovery
method would best reduce the occurrence of injury and clear HLa between innings is
crucial to prolonging optimal performance in pitchers at all levels of baseball.

3

Purpose
The purpose of the present study was to investigate the effects of two betweeninning recovery methods on pitching performance in male NCAA division II baseball
pitchers.
Delimitations
For the purpose of the present study, the following delimitations apply:
1) NCAA Division II, East Stroudsburg University of Pennsylvania baseball pitchers
2) Participants must be free from injury for the past 6 months
3) No heavy resistance training 24-48 hours prior to testing sessions
Limitations
For the purpose of the present study, the following limitations apply:
1) Compliance to preconditions of testing
2) Consistent effort throughout both testing sessions
3) Rapsodo technology error
4) Non-Randomized recovery method per session
Operational Definitions
The following definitions applied directly to the present study:
Spin Rate – the amount of spin of a baseball after it is released. Spin Rate is
measured in revolutions per minute (rpm).
4

Electrical Muscle Stimulation – electrical impulses sent to muscle via electrodes.
These impulses act as Action Potential’s to induce the muscle to contract. The subject
was sitting down for 6 minutes with electrodes placed on the Anterior and Posterior
Deltoid muscle of the throwing arm. The stim machine was set at a frequency of 9Hz,
with biphasic symmetry, and a pulse width of 250 milliseconds.
Passive Recovery – the subject sitting down with a jacket on for 6 minutes
between the first and second simulated inning.
Release Height – the distance (m) from the bottom of the pitching mound to the
pitcher’s active hand when he releases the ball to the catcher.
Rapsodo 2.0 Pitch Tracker – a pitch tracking device that provides instant
feedback as well as analyzes spin rate, command, velocity, movement, and mechanics of
each pitch.
Summary
Along with the necessity of maintaining velocity during games for pitchers,
comes the need to maintain other performance factors like accuracy, spin rate, and
release height. The Rapsodo Pitching Unit allows researchers to track such performance
measurables and has been used by numerous professional baseball organizations to
monitor and track their pitcher’s progress (Boddy, 2016). There has been no study to
date that has combined the performance measurables recorded from the Rapsodo
Pitching Unit with different between inning recovery methods. Lack of research
5

examining in-game recovery methods in collegiate baseball warrants further study. The
two methods this study examines is Passive Recovery (PR) and Electrical Muscle
Stimulation (EMS). Therefore, finding the best recovery method during competition,
while using the most up to date technology, could be key to maintaining performance
for collegiate baseball pitchers.

6

CHAPTER 2: LITERATURE REVIEW

Biomechanics of the Throwing Motion
For years the throwing motion related to baseball pitching has been broken
down and analyzed by coaches, scouts, and bio mechanists. Generally, the throwing
motion can be divided into 6 sequential parts: windup, stride, arm cocking, acceleration,
deceleration, and follow through; all of which piece together to form a ballistic yet fluid
motion (Chu, Jayabalan, Kibler, & Press, 2016). The windup begins when the stride leg
drifts back behind the mound and ends with the stride leg elevated and fully flexed
while the stance leg is isometrically contracting (Chu et al., 2016). The stride represents
the descending of the stride leg, the separation of the throwing hand and non-throwing
hand, and the corresponding touchdown of the stride foot to the ground in full-stride
(Chu et al., 2016). The arm cocking phase starts at the end of the stride phase, where
the trunk and pelvis rotate towards the desired target and the throwing arm sets into
maximal external rotation at the Glenohumeral joint (Chu et al., 2016). The acceleration
phase begins when the arm is in maximal external rotation and ends with release of the

7

ball (Chu et al., 2016). The trunk and pelvis continue rotating towards the target, and
ultimately propel the torso over a flexed trunk and extended knee (Chu et al., 2016). The
deceleration phase begins at the end of the acceleration phase when the ball leaves the
hand, and ends when the throwing shoulder has reached peak internal rotation (Chu et
al., 2016). Most of the forces slowing down the arm are absorbed by the group of
muscles that make up the rotator cuff (supraspinatus, infraspinatus, teres minor, and
subscapularis) at this time. The last phase is the follow-through, where the pitcher’s
stance leg flies forward and the throwing arm ceases movement (Chu et al., 2016). It is
important to note that like many exact repetitive movements in sports, the throwing
motion can become catastrophic to the individual performing it very quickly. One
muscular imbalance or improper weight-shift can cause acute/chronic injury. Each
phase of throwing must be so calculated that even slight error/deviation during a phase
can cause injury to the athlete. Because of limb length discrepancies, mass differences,
and muscular output differences between pitchers, there is no one motion that will
work for every pitcher. Along with variations in mechanics, variations in pitching
measurables exist between pitchers as well. One of the most recent variable studied for
its use in professional baseball, and its use as a possible monitoring tool is spin rate.
Spin Rate
It has been well established that one of the main keys to success for a starting
pitcher at any competitive level is for them to maintain the velocity of all pitches
throughout the entirety of a baseball game. However, until recent, the importance of
8

the rate of spin of a pitcher’s different pitches has not been studied. Many pitchers
ultimately may throw the same velocity on different pitches, but their actual spin rates
in revolutions per minute (rpm) may be drastically different. Higuchi examined
differences in batted balls with same velocities but different spin rates in elite level
hitters (Higuchi, Morohoshi, Nagami, Nakata, & Kanosue, 2013). 30 pitches were thrown
at a set speed of 81 miles per hour (mph), but the pitching machine they were propelled
from would randomly select 1 of 3 different rates of spin (1800rpm, 2400rpm, or
3000rpm) for the pitch. There was a statistically significant correlation between rate of
spin and deviation from the “sweet-spot” of the bat when hitters swung (Higuchi et al.,
2013). As rate of spin increased, the distance between ball-center and the sweet spot of
the bat increased, meaning less balls were batted on the sweet spot or barrel of the bat
(Higuchi et al., 2013). One reason given as to why there was an increase of sweet spot
misses was that the spin of pitches thrown with higher rpm’s oppose the gravitational
force acting on the ball, leading to less of a decrease in ball path height. This observation
is called the Magnus Effect (Higuchi et al., 2013). This research explains that pitcher’s
with higher rpms on their fastballs may be harder to consistently contact because of the
increased Magnus effect on their ball flight. Consistency in a pitcher’s spin rate along
with velocity throughout a game could be crucial to maintaining optimal performance.
Since there would be an expected linear decline of spin rate and throwing velocity over
multiple innings of pitching, pitchers’ need for an efficient between inning recovery

9

method is crucial. Finding the best recovery method to maintain performance would be
vastly importantly to the performance of baseball pitchers at all competitive levels.
Increases in Injuries and Practical Assessments
Without knowledge or proper recovery techniques, pitchers can fatigue in-game
rapidly. In baseball it is well known that frequent pitching, or overhead throwing in any
manner, can lead to arm injuries. However, it has only been since the last decade or two
where this growing epidemic of injury/overuse has been vigorously studied. A recent
study by Wilson aimed to look at the incidence of Ulnar Collateral Ligament
Reconstruction surgery (UCLR) among MLB baseball pitchers from 1974-2015. Data
showed that from 1974-1995 there was an average of <2 UCLR surgeries per year in
MLB pitchers, but from 2002-2012 there was an average of >14 UCLR surgeries per year
with a peak of 33 UCLR in 2012 (Wilson, Pidgeon, Morrell, & DaSilva, 2015). Overuse
injuries have been found to be even more common in youth baseball as of recent. A
study by Lyman showed that in an increase in pitches thrown throughout the year and
more than 75 pitches thrown per game led to an almost 52% increase risk of shoulder
injury and a 35% increase in elbow pain across youth baseball pitchers (Lyman, Fleisig,
Andrews, & Olsinski, 2002). An increase number of pitches has also been shown to
disrupt repeatable mechanics (release height, stride length) in MLB pitchers, which is
theorized to be caused by fatigue and may lead to an increase in injury rates (Whiteside,
Martini, Zernicke, & Goulet, 2016).

10

Another cause for injury in pitchers, and athletes alike, is lack of physical
conditioning. Baseball pitcher’s motions are a detailed, complex, multi-step process that
allow little room for error. Even if the mechanics of a certain pitcher is flawless, the
stress a pitcher places on their body during this motion becomes greater as pitch counts
rise. Most pitchers not only need to maintain longevity in each performance, but they
must be able to throw maximally at certain points as well. Without proper strength, a
pitcher may not be able to throw with enough velocity to get batters they’re facing out.
Secondly, without proper strength, a pitcher may fatigue faster. Knowledge of a pitchers
strength/conditioning may be key to maintaining optimal performance throughout a
baseball season, which is why testing measures like the 1-RM back squat could be
important. The 1-RM back squat is a test of maximal strength of the lower body and has
been correlated to various performance measures like jumping and sprinting (Chelly,
Chérif, Amar, Hermassi, Fathloun, Bouhlel, Tabka, & Shephard, 2010). Being that the
amount of force produced from the lower body segments during the pitching delivery is
high, the velocity at which a pitcher can throw may be influenced by the amount of
weight they can squat. A recent study highlighted lower extremity muscle activation
during the pitching motion through EMG analysis in 11 highly skilled baseball pitchers
(Campbell, Stodden, Nixon, 2010). The muscles marked for analysis during this study
were the Vastus Medialis, Rectus Femoris, Biceps Femoris, Gluteus Maximus, and
Gastrocnemius on both the stride leg and the trail leg of each subject (Campbell,
Stodden, Nixon, 2010). Researchers broke down the pitching motion for analysis into 4
11

distinct phases; phase 1 was the initiation of the pitching motion until the stride knee
was completely vertical, phase 2 was peak stride knee flexion until the stride foot
contacted the ground, phase 3 was stride foot contact until the ball was released, and
phase 4 was ball release until 0.5 seconds after release (Campbell, Stodden, Nixon,
2010). Mean EMG percentage values were highest during phase 3 for both the stride leg
and trail leg, with the largest values observed from the vastus medialis (166 ± 47), rectus
femoris (167 ± 38), and gluteus maximus (108 ± 33) via the stride leg, and the largest
values from the gastrocnemius (172 ± 57) and gluteus maximus (141 ± 71) via the trail
leg (Campbell, Stodden, Nixon, 2010). When comparing the muscle activation during the
phases of pitching with the muscle activation during the barbell back squat, there are
several similarities. A study by Yavuz on back squat EMG analysis during maximum loads
shows muscle activations for the quadriceps and hamstrings groups. During the back
squat, the highest EMG activities were observed from the vastus medialis (48.3 ± 14.3),
vastus lateralis (45.9 ± 13.9), rectus femoris (37.9 ± 12.1), and gluteus maximus (28.8 ±
18.9) during the descending phase, and from the vastus medialis (49.3 ± 13.9), vastus
lateralis (48.5 ± 17.2), rectus femoris (36.0 ± 13.8), and gluteus maximus (47.3 ± 27.7)
during the ascending phase (Yavuz, Erdag, Amca, Aritan, 2014). With the observed
correlation between muscle activation in the lower extremities during the pitching
motion and the barbell back squat, the 1-RM back squat would be a valid assessment of
pitchers’ strength in relation to their sport.

12

Although having a strong base of strength to support the pitching delivery is
vital, pitchers must also be able to recover from training before, after competition, and
try to even during competition. Being that the most important aspect of any athletes’
career is actually their time competing, being able to recover as efficiently as possible
will allow for not only longer bouts of competition, but also more frequent ones. Finding
an optimal recovery method that allows for the highest degree of recovery for pitchers
between innings is therefore a necessity.
Electrical Muscular Stimulation
Electrical muscle stimulation (EMS) is a therapeutic modality used to enhance
muscular activation and promote blood flow to affected areas of the body. Electrical
impulses are sent through electrodes placed on the skin of the subject which mimic
action potentials at the neuromuscular junction. EMS has been widely used as a form of
therapy post-injury to promote blood flow to injured areas when patients cannot
perform proper range of motion or strength tasks. Recently, EMS has been researched
for its possible uses in sports performance enhancement/recovery. A study by Neric
looked at different recovery methods (passive recovery and EMS) in 30 competitive
swimmers post-exercise. Both passive recovery and EMS were administered randomly,
and total recovery time was 20 minutes. HLa levels were compared from rest, 10
minutes into recovery, and 20 minutes into recovery (Neric, Beam, Brown, & Wiersma,
2009). HLa levels decreased significantly from rest during both recovery methods after
10 minutes, but only continued to decrease after 20 minutes when EMS was
13

administered (Neric et al., 2009). With the continued decrease in HLa levels after 20
minutes of recovery EMS showed to be an optimal method of recovery for swimmers,
especially because of the possibility of competing multiple times within a 30-minute
time period (Neric et al., 2009). Comparably, swimmers may have to compete in
multiple events during a single meet just like baseball pitchers may have to throw
multiple innings in a single game. For the majority of a competition, the rest between
the next race/inning is unknown, so finding a recovery method that decreases
fatigue/maintains performance optimally is imperative.
Passive Recovery
Passive Recovery (PR) is one of the most widely used methods of recovery in
many sports, especially baseball. A typical PR protocol consists of having a subject sit
down, stand, or stretch immediately following exercise/competition. Many pitchers
during baseball games use PR as their main method of recovery between innings
pitched, except most times the pitcher is wearing a jacket while resting. Many times
during competition a pitcher will have unknown periods of rest in-between innings,
which makes it very difficult to establish an exact between-inning recovery protocol.
Even with other recovery methods being researched in sports today, PR is still
extensively used because of its simplicity and economical advantage (no equipment is
necessary). One study on recovery methods looked at correlations between in-game
recovery methods, one of which being PR, and HLa, RPE, heart rate, and range of motion
in 21 intercollegiate Division I pitchers (Warren., Szymanski., Landers., 2015). After
14

pitchers threw a simulated inning of 15 pitches (entirely fastballs) they would perform a
6-minute PR protocol before their next simulated inning. Results showed that HLa levels
did not change significantly when compared pre-recovery to post-recovery, however
RPE decreased when compared pre-recovery to post-recovery (Warren., Szymanski.,
Landers., 2015). Although biological evidence like HLa testing has shown PR to be a
slower means of lowering fatigue, PR has been established as a reliable protocol that
consistently lowers RPE and heart rate.
Research on Recovery Methods
There are various recovery methods used by athletes before and after
performance to decrease fatigue. Therefore, finding an optimal recovery method
between innings for pitchers could allow them to maintain increased performance levels
for longer durations. Although research is minimal, Warren was able to examine the
effects of passive recovery and electrical muscle stimulation on pitchers during a
simulated game (Warren et al., 2015). 21 Pitchers from a division I university
participated in the study. Each pitcher was required to throw 15 pitches per inning, for 5
innings, for a total of 75 pitches. Each pitch thrown was a fastball, and each pitcher was
asked to throw at or above 95% effort. Before each pitcher started throwing, one of
three recovery methods were randomly selected for that specific testing day. All
recovery protocols lasted 6 minutes and were administered following the 15th pitch of
each inning. Before and after recovery protocols were administered, the subject’s heart
rate and HLa were recorded. PR was explained as sitting down and wearing a jacket for
15

the entirety of the recovery time, and the EMS protocol had practitioners administer
electrodes on the triceps and biceps brachii, anterior and posterior deltoid, and the
anterior and posterior upper trapezius of each subject’s throwing arm (Warren et al.,
2015). EMS was shown to decrease HLa concentrations significantly (p<0.001) from
post-pitching to post-recovery, whereas passive recovery did not change (p = 0.04)
(Warren et al., 2015). While HLa levels decreased significantly, HLa accumulation was
never high enough to decrease velocity or induce skeletal muscle fatigue (Warren et al.,
2015). Although Warren’s study showed a significant decrease in HLa concentrations for
the EMS protocol, there may be a limitation in the experimental design that could have
skewed the results. One major limitation is that subjects were only instructed to throw
fastballs during testing. Although this method may assure little variation in throwing
velocity across the entirety of the study, it does not match the purpose of a “simulated”
inning. Pitchers during competition throw many more pitches per inning besides
fastballs i.e. changeups, curveballs, sliders, etc., thus having multiple innings of only
fastballs may not elicit the same physiological effects that would occur during real
competition. To have a better understanding of the physiological toll that is placed on a
pitcher during competition, a study where pitchers throw all their respective pitches
during simulated innings is necessary.

16

CHAPTER 3: METHODOLOGY
The purpose of this study was to investigate the effects of two between-inning
recovery methods on pitching performance in male NCAA division II baseball pitchers.
This chapter will present the participants, inclusion requirements, procedures, and data
analysis.
Subjects
Six male college-aged NCAA Division II pitchers volunteered to participate in this
study during the non-competition part of their baseball season. Out of the six pitchers,
only five pitchers completed the study due to technological errors associated with the
Rapsodo 2.0 Pitching Unit. This study received approval by the Institutional Review
Board for the Protection of Human Subjects at East Stroudsburg University (Appendix A).
All (5) pitchers read and signed an informed consent form and a Physical Activity
Readiness Questionnaire Plus (PAR-Q+) (Appendix B & C) approximately a week before
the start date of the study. Table 1 reports descriptive data for all demographic
variables. Each subject reported to be free from injury during the time of the study, and

17

at full health. All subjects had thrown for the past 5 weeks during their collegiate fall
baseball season before the 2 weeks of testing occurred.
Table 1. Subject Demographics

Subjects
Subject 1
Subject 2
Subject 3
Subject 4
Subject 5
Mean
SD (±)

Age

Height
(cm)

Weight
(kg)

BMI
(% Fat)

Years College of Experience

20
19
19
19
22

187.9
182.9
195.6
190.5
188.0

93.2
82.8
104.1
95.9
88.2

26.4
24.8
27.3
26.5
25.0

2
1
1
1
3

19.8
1.2

189.0
4.1

92.8
7.2

26.0
1.0

1.6
0.8

Values were rounded to 1 significant figure.
Procedures
The subjects underwent a familiarization session with all equipment being used
for pitching purposes. All subjects underwent 1-RM back squat testing prior to the study
commencing. The 1-RM testing design was as follows: The subjects were taken through
a dynamic warmup, which started as dynamic stretching and ended with ballistic
movements i.e. bounds and skips. All subjects had previously undergone a
familiarization session in back squatting and had established proper back squat
technique, as per their Strength and Conditioning coach. Each subject was instructed to
follow the protocol of 8-10 repetitions as a warmup set, 6 reps as their first set, 2-4 as a
second set, 1-2 reps as their third set, and then from there on they were instructed to
do no more than 1 repetition per set, with the ultimate goal as achieving their 1-RM
back squat at no more than 5-6 sets. The weight increased after each set was dictated
18

by the subject and the Strength and Conditioning staff during testing. Termination of
testing happened when the subject could either not lift the loaded bar back up from the
down position, or when a member of the Strength and Conditioning staff saw a flaw in
proper technique of a subject i.e. lack of proper depth (90 degrees at hip, knee, and
ankle), excess knee valgus. Once each subject attained their 1-RM back squat, their
testing numbers were recorded.
This study aimed to simulate a normal (in-game) pitching environment for all
subjects. The subject testing sessions for pitching occurred individually on 2 separate
occasions, where environmental conditions were similar, every 7 days. Pitchers were
tested every 7 days because it followed their throwing schedule for the Fall season.
Testing sessions ran for approximately 30 minutes and were designed as follows:
Practitioner’s placed Polar Heart Rate monitors directly below the subject’s sternum and
had them rest for 5 minutes to acquire resting heart rate levels. Subjects’ baseline HLa,
Local and Overall RPE were taken after 5 minutes of resting. HLa was acquired by a
Lactate Pro Analyzer on the non-dominant fingertips of each subject. The Lactate Pro
Analyzer was calibrated before each testing session. Once baseline data was recorded,
the subjects completed a dynamic upper and lower body warm-up and started a light
catch for 10-15 minutes. After their catch, pitchers threw 5-10 warmup pitches from the
mound to simulate a bullpen before throwing in a game. After the simulated bullpen
warmup pitches, pitchers threw 5 pitches to simulate the amount of pitches thrown
before an inning commences. After 5 warm-up pitches were thrown, inning 1
19

commenced. During inning 1, subjects threw 15 pitches (with multiple variables being
measured after each pitch (heart rate, velocity, release height, spin rate, accuracy).
There was not a set script on what pitch/number of pitch types were thrown in the set
of 15 because of the necessity of the subjects’ pitching coach calling out pitches. This
allowed for randomization of pitch types, which made the testing session as close to a
real game scenario as possible. These 2 testing sessions were used as bullpen sessions
for the pitcher’s that threw in this study, so pitch type was called out by the pitching
coach. Each subject threw different totals of each pitch throughout the testing sessions,
but every subject threw 30 pitches total in each testing session. Ball and strike calls were
given by the catcher and were not told to the subject throwing. Velocity, Release Height,
and Spin Rate were all recorded by the Rapsodo 2.0 Pitching Unit, a high-speed camera
used for pitch tracking purposes. After 15 pitches, Local and Overall RPE were recorded,
and subjects were then given one of two recovery methods (EMS or PR) for 6 minutes
(Warren et al., 2015). On day 1 of testing all the subjects were administered the PR
protocol, and on day 2 the EMS protocol. HLa was taken at the beginning of the 6minute recovery protocol to determine pre-recovery HLa, and immediately postrecovery. Heart Rate was recorded every 30 seconds during recovery (Warren et al.,
2015). Local and Overall RPE were recorded post-recovery as well. After the 6 minutes
of recovery was completed, the subjects threw 5 warmup pitches and then completed
their 2nd inning. 15 more pitches were thrown during the 2nd inning, with Heart Rate
being recorded after each pitch, as well as the pitching measurables from the Rapsodo
20

2.0 Pitch Tracker. After the 15 pitches were thrown, Local and Overall RPE were
recorded as well as HLa. Once the last HLa was drawn, the subjects performed their
normal cool down method which involved light jogging and static stretching.
Data Analysis
Descriptive data was collected for all variables. Mean, standard deviation, and
delta scores were collected across conditions (PR, EMS). Microsoft Excel 2016 was used
for all analysis

21

CHAPTER 4: RESULTS
The purpose of the study was to describe fatigue and overall pitching
performance (Velocity, Strikes thrown, Spin Rate, and Release Height) across two
recovery techniques in NCAA division II collegiate pitchers. This chapter will present
descriptive statistics for accuracy, HLa, heart rate, local/overall RPE, velocity, spin rate,
and release height.

22

Table 2. Fastball Pitch Totals and Differences in Accuracy Across Recovery Methods
Passive Recovery

# of Pitches

Pre PR Strikes
Pre PR Balls
Post PR Strikes
Post PR Balls
PR Difference in Strikes
PR Difference in Balls

25
23
24
16
-4%
-30.5%

EMS

# of Pitches

Pre EMS Strikes
Pre EMS Balls
Post EMS Strikes
Post EMS Balls
EMS Difference in Strikes
EMS Difference in Balls

28
20
22
19
-21.5%
-5%

Table 2 depicts fastball pitch totals and differences in accuracy across PR and
EMS. The difference in strikes thrown for PR was (-4%), while balls thrown was (-30.5%).
The difference in strikes thrown for EMS was (-21.5%), while balls thrown (-5%).

Mean Fastball Velocity Pre and Post Recovery
80
79

Velocity (mph)

78
Mean Velocity Pre
and Post PR

77
76
75
74

Mean Velocity Pre
and Post EMS

73

72
71
70

Inning 1

Inning 2

Figure 1: Mean Fastball Velocity Pre and Post Recovery
Figure 1 depicts mean fastball velocity (mph) pre (Inning 1) and post (Inning 2)
PR and EMS. Mean velocity during inning 1 for Pre PR was 79.8 mph, while mean
velocity for Pre EMS was 76.1 mph. Mean velocity during inning 2 for Post PR was 79.1
23

mph, while mean velocity for Post EMS was 77.2 mph. A 0.8% decrease in velocity was
shown pre-recovery to post-recovery for the PR session, while an increase of 1.4% was
shown pre-recovery to post-recovery for the EMS session.

Mean Fastball Spin Rate Pre and Post Recovery
2000
1950

Spin Rate (rpm)

1900
1850
1800

Mean Spin Rate Pre and Post
PR

1750
1700

Mean Spin Rate Pre and Post
EMS

1650
1600
1550
1500

Inning 1

Inning 2

Figure 2: Mean Spin Rate Pre and Post Recovery
Figure 2 depicts mean fastball spin rate (rpm) pre (Inning 1) and post (Inning 2)
PR and EMS. Mean Pre PR spin rate for inning 1 was 1866 rpm, while mean Pre EMS spin
rate for inning 1 was 1815 rpm. Mean Post PR spin rate for inning 2 was 1903 rpm,
showing a 2% increase from inning 1. Mean Post EMS spin rate for inning 2 was 1794
rpm, showing a 1.1% decrease from inning 1.

24

Mean Release Height Pre and Post Recovery
2

1.8

Release Hwight (m)

1.6
1.4
1.2
Mean Release Height Pre
and Post PR

1
0.8
0.6

Mean Release Height Pre
and Post EMS

0.4
0.2
0

Inning 1

Inning 2

Figure 3: Mean Release Height Pre and Post Recovery
Figure 3 depicts mean release height (m) pre (Inning 1) and post (Inning 2) PR
and EMS. There was no change in release height across pre to post recovery, but the PR
session averaged a higher release height (1.50m) compared to the EMS session (1.48m).

Rating of Percieved Exertion

Mean Overall and Local RPE Compared to
Recovery Methods
10
9.5
9

PR Local RPE

8.5
PR Overall RPE

8

EMS Local RPE

7.5

EMS Overall
RPE

7
6.5
6

Inning 1

Inning 2

Figure 4: Mean Overall and Local RPE Compared to Recovery Methods
25

Figure 4 depicts the mean local and overall RPE values pre (Inning 1) and post
(Inning 2) recovery. Both local and overall RPE decreased .2 after the EMS recovery. PR
local RPE increased .2 after recovery, while overall RPE for PR stayed constant at 8.6.
The Borg RPE scale (6-20) was used to measure both local and overall RPE.

Mean Heart Rate Post-Pitching vs Post-Recovery
130
N=4

Heart Rate (bpm)

110
90
70

PR Pre Recovery-Post
Recovery

50

EMS Pre Recovery-Post
Recovery

30
10
-10

Pre Recovery

Post Recovery

Figure 5: Mean Heart Rate Pre-Recovery vs Post-Recovery
Figure 5 depicts mean heart rate Pre and Post PR and EMS. PR mean heart rate
decreased after the 6-minute recovery by 10% (11.5 bpm), while EMS mean heart rate
decreased only by 2% (2.0 bpm). Data from 4 subjects was analyzed from the PR session
because of an outlier.

26

Mean PR and EMS BLa Concentrations
4
3.5

HLa (mMol)

3

N=4

2.5
EMS

2

PR

1.5
1
0.5
0

Rest

Pre Rec

Post Rec

Post 2nd

Figure 6: Mean PR and EMS HLa Concentrations
Figure 6 depicts mean HLa concentrations during rest, pre-recovery, postrecovery, and post 2nd inning of pitching. Mean PR HLa concentrations increased 40%
(0.85 mMol) from pre-recovery to post-recovery. Mean EMS concentrations decreased
29% (0.88 mMol) from pre-recovery to post-recovery. Data from 4 subjects (n=4) was
analyzed from the PR session because of an outlier.

Table 3. 1-RM Squat Compared to Highest Fastball Velocity
Subjects

1RM Back Squat (kg)

Highest FB Velo (mph)

P1
P2
P3
P4
P5

165.2
151.6
144.8
142.5
122.2

84
84
75
82
86

Table 3 depicts each subjects 1-Repetition Maximum (1-RM) back squat and each
subjects’ highest recorded fastball velocity. P5 recorded the highest fastball velocity at
27

86mph, while also recording the lowest 1-RM back squat value at 122.2kg. P1 and P2
recorded the second highest fastball velocities at 84mph, and both also recorded the
two highest back squat values (P1=165.2, P2=151.6).

28

CHAPTER 5: DISCUSSION, CONCLUSION, FUTURE RECOMMENDATIONS
The purpose of this study was to describe which recovery method may better
sustain velocity, spin rate, release height, and accuracy. Because the time a pitcher has
to rest between innings constantly varies, it is essential to find a recovery method that
best decreases fatigue and maintains performance measurables (i.e. velocity, spin rate)
throughout a game. This chapter will present a discussion, conclusion and future
recommendations.
Discussion
An important aspect of pitching that has been shown to be influenced by fatigue is
accuracy. An increase in fatigue can lead to a decrease in sensorimotor function (Warren
et al., 2015). From a pitching perspective, a loss in sensorimotor function could affect
the amount of balls and strikes thrown in a pitching performance. The accuracy of
pitches was totaled for both PR and EMS sessions, and then grouped into pre-recovery
and post-recovery groups (table 2). The results show that 4% less strikes were thrown
after PR was performed, compared to 21.5% less strikes when EMS was administered.
Snyder, 2013 had results that showed EMS, not PR, being the recovery method that
29

better maintained strikes thrown across multiple innings of recovery. This is theorized to
be because of EMS’ ability to better clear lactate than PR, subsequently decreasing
fatigue. It is believed that the present study showed a greater decrease in accuracy after
EMS because of the small number of subjects, and the limit of only 2 simulated innings
thrown (30 pitches). With more pitches thrown per subject, and additionally more
subjects, there may be a difference in which recovery method would better maintain
accuracy across innings.
Results suggest that EMS may better sustain velocity during performance but
may also reduce spin rate. Figure 1 shows mean fastball velocity pre-recovery to postrecovery for EMS increasing 1.1 mph (1.4%), while mean velocity for PR decreased 0.8
mph (8%). On the other hand, in figure 2, mean spin rate decreased 1.1% (1815rpm to
1794rpm) after EMS, and increased 2% (1866rpm to 1903rpm) after PR. Velocity may
have been maintained better during the EMS session because of an overall larger
decrease in mean HLa concentrations after EMS, when compared to PR. Mean HLa
concentrations decreased 29% (.88mmol) post-EMS recovery, and actually increased
40% (.85mmol) post-PR (figure 6). However, only data from 4 of the 5 subjects were
analyzed for PR HLa concentrations because of a present outlier. This decrease in HLa
for EMS recovery is consistent with previous research shown by Warren et al. 2015,
where EMS showed larger decreases in post-recovery HLa when compared to active
recovery (AR) and PR. Larger decreases in HLa during the EMS recovery method are
understandable because of the promotion of new blood flow to the electrically
30

stimulated areas, which causes HLa to clear more rapidly. Because of the clear link
between fatigue and performance, and an increase in HLa corresponding to an increase
in fatigue, higher HLa levels may reduce pitching measurables like velocity. Because EMS
was able to clear HLa more effectively than PR, subjects were able to maintain velocity.
It is important to note that one pitching measurable that did not change after PR, and
changed only minimally (.02) after EMS was mean release height (figure 3). Research by
Whiteside et al.2016 demonstrated that release height did not decrease until the 6 th
inning in a random selection of MLB pitchers across a 9-inning pitching performance. It
is theorized that because the subjects were only required to throw two simulated
innings per recovery session in this study, no decrease in mean release height was
found.
Although velocity was found to decrease less after EMS than PR, the subjects’
mean pitch velocities were significantly less on the EMS testing session day when
compared to the PR testing session day. The mean velocity for the first simulated inning
was 76.1mph for the PR session, and was only 73mph for the EMS session. The second
simulated inning for PR showed a decrease of 1.1mph with a mean velocity of 75mph
while the second inning for EMS showed a decrease of only 0.2mph with a mean
velocity of 72.8mph. The apparent difference in velocity could potentially be the reason
behind a shown decrease in spin rate during the EMS protocol, and in increase in spin
rate during the PR protocol (figure 2). This difference of 3.1mph on testing days could be
multifactorial, but one greater possibility is noncompliance to preconditions i.e. effort.
31

All subjects were told to throw their simulated innings at “game speed”, and many
pitchers velocities decreased from the PR session to the EMS session. For future
recommendations, phrases like “Throw at 95% of your best pitch” should be used,
because it has shown to effective in pitching research (Warren et.al, 2015).
Mean local and overall RPE (pre-recovery and post-recovery) barely changed
(figure 4). The EMS session reported a mean decrease in overall/local RPE by 0.2 after
recovery, while the PR session reported a mean increase in local RPE of 0.2 and no
change in overall RPE (figure 4). Because the subject amount was only 5 pitchers, it
would be difficult to see a true subsequent change in RPE across various recovery
methods. This is comparative to a study done by Snyder, 2013 on the effects of recovery
methods on collegiate pitching performance. Snyder found no significant difference for
overall and local RPE across various recovery methods (Snyder, 2013).
Mean heart rate pre-recovery to post-recovery exhibited one of the largest
changes across recovery methods. After PR, mean heart rate decreased 10% (11.5bpm),
compared to after EMS when heart rate decreased only by 2% (2.0 bpm). This is not
comparative to research done by Warren et al. 2015. Warren showed no change in
mean heart rate when comparing EMS and PR (both measures decreased by 29%). One
possible explanation for the larger decrease in heart rate from PR to EMS is the
difference in post-pitching heart rate values from subjects on the different testing
sessions. When subjects P1 and P2 finished their first simulated inning on their PR
testing session, they reported post-pitching heart rates of 101bpm and 128bpm,
32

respectively. After recovery, their heart rates decreased to 83bpm and 95bpm (-18bpm
and -33bpm). However, when subjects P1 and P2 finished their first simulated inning on
their EMS testing session, they reported post-pitching heart rates of 82bpm and 91bpm,
respectively. After recovery, their heart rates increased to 93bpm and 98bpm (+11bpm
and +7bpm). With the drastic differences in post-pitching heart rate for the PR and EMS
sessions, a larger possible decrease in post-recovery heart rate was to be expected.
Lastly, no comparison was shown between max fastball velocity and 1-RM back
squat. There ae many factors that go into allowing a pitcher to throw hard, so basing
high velocity off of one (like 1-RM back squat) did not turn out feasible. Further studies
with EMG analysis may be better to show muscle recruitment patterns during pitching
and may be pinpoint active musculature better than a 1-RM test comparison.

Future Recommendations
The number of simulated innings pitched during this study was 2 per recovery
session, with a total of 15 pitches thrown each inning. Further studies with more innings
thrown, closer to 6-9, should elicit greater differences in HLa, spin rate, release height,
accuracy, and many other variables tested. Also, data was collected towards the end of
the subjects Fall baseball season. For more accurate/valid results, having testing
sessions held in the subjects competitive Spring season may increase variables like
accuracy and velocity. In terms of data collection, multiple errors were reported when
33

using the Rapsodo Pitching Unit for pitch tracking (collecting spin rate & release height).
Many spin rates and release heights never registered for multiple pitches per subject, so
looking at comparisons between individual data became unreliable. With the amount of
pitches that were subsequently “missed” by the Rapsodo Pitching Unit, each subject’s
off-speed pitches that were thrown i.e. sliders, curveballs, changeups had to be omitted
from data reporting purposes. The only pitch type that was able to be used for the
purposes of this study was the fastball, because of the higher number that was able to
be recorded for each subject. In the future, multiple weeks of possible testing sessions
would be available in case such errors were to occur again.
Lastly, the number of type of pitches thrown per subject was not consistent in
this study. The subjects used these testing sessions as their “bullpens” to prepare for
weekend competitions in their Fall season, meaning the number of pitch types was
dictated by their respective pitching coach. In one aspect, having a different amount of
pitch types makes the present study more game specific, and allows researchers the
ability to observe and collect data from subjects in the closest “in-game” like scenario.
However, this also made the present study impossible to compare subject to subject.
For future studies the number of pitch types being thrown should remain consistent
across all subjects. It would be easiest to make a script that all subjects had to follow,
which would make results more valid.

34

CONCLUSION
Despite limitations, this study shows importance to further investigate in-game recovery
methods for pitchers. Increases in pitching injuries over the past two decades in baseball
has made research on finding an optimal in-game recovery method a necessity. This
study does not show favor of one recovery method over another in all aspects of
pitching performance (velocity, spin rate, accuracy). However, further research involving
EMS and PR could be potentially show one method as an optimal recovery modality.

35

APPENDICES
APPENDIX A IRB FORM

36

APPENDIX B INFORMED CONSENT FORM
Informed Consent for Scientific Study
Title of Investigation: The Effects of Two Recovery Methods on Physiological and
Performance Factors in NCAA Division II Baseball Pitchers.
Principle Investigator: Brandon Snyder
Overview of Study
Understanding fatigue is extremely important when determining continuation of
competition in all sport athletes, especially in baseball pitchers. This fatigue may be able
to dissipate with adequate rest between innings, but the average rest varies drastically
because of unpredictability in game situations. Current research varies support between
multiple methods of recovery, but the two this study will focus on is Passive Recovery
(PR), and Electro muscular Stimulation (EMS). Along with the necessity of maintaining
velocity during games for pitchers comes the need to maintain other performance
factors (i.e. Spin Rate, Spin Direction, Release Height, Vertical and Horizontal Break). The
Rapsodo Pitching Unit allows researchers to track such performance measurables and
has been used by numerous professional baseball organizations to monitor and track
their pitcher’s progress. There has not been a study to date that has combined the
performance measurables recorded from the Rapsodo Pitching Unit with different
between inning recovery methods. Therefore the purpose of this study is to investigate
the effects of two between inning recovery methods on pitching performance in male
NCAA division II baseball pitchers.

37

Testing Sessions
There will be 2 total testing sessions during this study, and they will occur in the
Arena of Koehler Fieldhouse located on the campus of East Stroudsburg University of
Pennsylvania. The testing sessions will occur 1 week apart (7 days) and will follow the
subsequent format:
Session 1: Electrical Muscular Stimulation
Subjects weight and height will be recorded 15 minutes prior to their individual
testing session. Polar heart rate monitors will then be placed along the distal aspect of
the subject’s sternum, and resting heart rate will be recorded. After heart rate is
recorded, subject’s resting BLa will be taken from their non-dominant hand via lancet.
BLa will be analyzed using a Lactate Pro Analyzer. Resting local and overall RPE will then
be acquired via the Borg RPE Scale (6-20). After all resting measurements are recorded,
subject’s will warmup and start to throw. Subject’s will throw 5 warmup pitches prior to
their first simulated inning. The first inning consists of 15 pitches, where pitch type will
be dictated by the East Stroudsburg University pitching coach for each subject. After the
15th pitch is thrown, HLa, RPE, and heart rate are taken again. The subject will then
undergo electrical muscular stimulation (EMS) for 6 minutes, with electrodes being
placed on the anterior and posterior aspect of the throwing shoulder. After the 6minute recovery, HLa, RPE, and heart rate are recorded again. The second simulated
inning will then commence, and 15 more pitches will be thrown. After the 15 th pitch,
HLa, RPE, and heart rate will be recorded for a final time. During all 30 pitches thrown,
the Rapsodo Pitching Unit will be recording velocity, spin rate, and release height.
Catcher’s will be recording accuracy.
Session 2: Passive Recovery

38

Session 2 is the exact same testing procedure as Session 1, except the 6-minute
recovery protocol is Passive Recovery (PR) instead of EMS. The PR protocol calls for
subjects to sit in a chair with a jacket on for 6 minutes.
As a collegiate pitcher, the volume of throwing associated with this study should
raise little possibilities of musculoskeletal injuries. All individual information and will
remain anonymous. The data collected from this study will be used for presentations
with the possibility of scientific publications. You may withdraw from this study at any
time. Any additional questions before signing this consent form can be directed to
Brandon Snyder.
If any additional questions arise during or after the study, please contact Brandon
Snyder at:
Email: bsnyder12@esu.edu
YOU ARE NOW MAKING A DECISION ON WHETHER OR NOT TO PARTICIPATE IN THIS
STUDY. YOUR SIGNATURE INDICATES THAT YOU HAVE READ THE INFORMATION
PROVIDED AND WISH TO PARTICIPATE IN THIS STUDY.
I have read and understood the above explanation of the purpose and procedures for
this study and agree to participate. I also understand that I am free to withdraw my
consent at any time.
________________________
PRINT NAME

________________________
SIGNATURE

_________________________

___________

WITNESS SIGNATURE

DATE

39

APPENDIX C PAR-Q+

40

APPENDIX D BORG RPE SCALE

41

REFERENCES
Boddy, K. (2016, November 18). RAPSODO, TRACKMAN, AND PITCH TRACKING
TECHNOLOGIES – WHERE WE STAND.
https://www.drivelinebaseball.com/2016/11/rapsodo-trackman-pitch-trackingtechnologies-stand
Bogdanis, G. C., Nevill, M. E., Lakomy, H. K., Graham, C. M., & Louis, G. (1996). Effects of
active recovery on power output during repeated maximal sprint cycling. European
journal of applied physiology and occupational physiology, 74(5), 461-469.
Campbell, B. M., Stodden, D. F., & Nixon, M. K. (2010). Lower extremity muscle
activation during baseball pitching. The Journal of Strength & Conditioning
Research, 24(4), 964-971.
Chelly, M. S., Chérif, N., Amar, M. B., Hermassi, S., Fathloun, M., Bouhlel, E., Tabka, Z. &
Shephard, R. J. (2010). Relationships of peak leg power, 1 maximal repetition half back
squat, and leg muscle volume to 5-m sprint performance of junior soccer players. The
Journal of Strength & Conditioning Research, 24(1), 266-271.
Chu, S. K., Jayabalan, P., Kibler, W. B., & Press, J. (2016). The kinetic chain revisited: new
concepts on throwing mechanics and injury. PM&R, 8, S69-S77.
Hackney, R. G. (1996). Advances in the understanding of throwing injuries of the
shoulder. British journal of sports medicine, 30(4), 282.
Higuchi, T., Morohoshi, J., Nagami, T., Nakata, H., & Kanosue, K. (2013). The effect of
fastball backspin rate on baseball hitting accuracy. Journal of applied biomechanics,
29(3), 279-284.
Lyman, S., Fleisig, G. S., Andrews, J. R., & Osinski, E. D. (2002). Effect of Pitch Type, Pitch
Count, and Pitching Mechanics on Risk of Elbow and Shoulder Pain in Youth Baseball
Pitchers. The American Journal of Sports Medicine, 30(4), 463–468.
Monedero, J., & Donne, B. (2000). Effect of recovery interventions on lactate removal
and subsequent performance. International journal of sports medicine, 21(08), 593-597.
Neric, F. B., Beam, W. C., Brown, L. E., & Wiersma, L. D. (2009). Comparison of swim
recovery and muscle stimulation on lactate removal after sprint swimming. The Journal
of Strength & Conditioning Research, 23(9), 2560-2567.
Snyder, B. (2013). The Effects of Three Types of Recoveries on Collegiate Pitching
Performance. East Stroudsburg University Graduate College.
Warren, C. D., Szymanski, D. J., & Landers, M. R. (2015). Effects of three recovery
protocols on range of motion, heart rate, rating of perceived exertion, and blood lactate
42

in baseball pitchers during a simulated game. The Journal of Strength & Conditioning
Research, 29(11), 3016-3025.
Whiteside, D., Martini, D. N., Zernicke, R. F., & Goulet, G. C. (2016). Changes in a Starting
Pitcher’s Performance Characteristics across the Duration of a Major League Baseball
Game. International Journal of Sports Physiology and Performance, 11(2), 247–254.
Wilson, A. T., Pidgeon, T. S., Morrell, N. T., & DaSilva, M. F. (2015). Trends in revision
elbow ulnar collateral ligament reconstruction in professional baseball pitchers. The
Journal of hand surgery, 40(11), 2249-2254.
Yavuz, H. U., Erdağ, D., Amca, A. M., & Aritan, S. (2015). Kinematic and EMG activities
during front and back squat variations in maximum loads. Journal of sports
sciences, 33(10), 1058-1066.

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