Submarine Pitchers Independent Research The …27390... · performed on several aspects of baseball pitching, ... same for all baseball pitchers. The biomechanics and kinematics of

Submarine Pitchers

EXERCISES TAILORED TO MEET THE NEEDS OF SUBMARINE PITCHERS

Independent Research

Presented to

The Faculty of the College of Health Professions and Social Work

Florida Gulf Coast University

In Partial Fulfillment

Of the Requirement for the Degree of

Doctorate of Physical Therapy

By

Kurtis Mullaney and Michael Klein

2015

Submarine Pitchers

APPROVAL SHEET

This independent research is submitted in partial fulfillment

of the requirements for the degree of

Doctorate of Physical Therapy

______________________________________

Kurtis Mullaney

Michael Klein

Approved: May 2015

______________________________________

Dr. Shawn Felton, EdD, ATC, LAT

Committee Chair

______________________________________

Professor Kelley Henderson, M.Ed., LAT, ATC

Committee Member

The final copy of this independent research has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline.

Submarine Pitchers

Acknowledgements

Mike and I would like to thank several people for helping us to complete our independent

research project. First of all, we would like to thank the overwhelming support we have

always received from our families and loved ones, including Kelly, Michael, Kyle, Kameron,

Karson, and Kolby Mullaney, and Candice, Hannah, and Eva Klein. Also, we would like to

thank Dr. Shawn Felton and Professor Kelley Henderson for always rapidly responding,

being attentive to detail, showing immense patience, and working tirelessly to help us with

this research. We would also like to thank Dr. Arie van Duijn for his contributions in terms

of helping us learn and utilize the equipment needed for this project. Other faculty that aided

in completing this study included Dr. Mollie Venglar, Professor Tom Bevins, and Dr. Dennis

Hunt. This project took a lot of time, effort, and patience from all of us involved and we are

extremely grateful for the help. We would also like to thank all of the participants involved,

who sacrificed their time to help make this research happen. Lastly we would like to thank

our classmates, who were always there to support us and to keep us encouraged even when

we hit major roadblocks along the way. This has been a difficult but rewarding journey, and

we would not have been able to complete it without the support of all of those involved.

Submarine Pitchers 4

Table of Contents

Acknowledgements ................................................................................................................... 3

Abstract ..................................................................................................................................... 5

Introduction ............................................................................................................................... 6

Phases of Throwing ............................................................................................................... 9

Electromyography ............................................................................................................... 12

Motion Analysis .................................................................................................................. 14

Purpose .................................................................................................................................... 15

Research Question .................................................................................................................. 16

Hypothesis ............................................................................................................................... 16

Methods ................................................................................................................................... 16

Subjects ............................................................................................................................... 18

Instrumentation ................................................................................................................... 19

Procedure ............................................................................................................................ 20

Exercise Descriptions .......................................................................................................... 23

Data Analysis ...................................................................................................................... 26

Results ..................................................................................................................................... 26

Discussion ............................................................................................................................... 33

Limitations .......................................................................................................................... 35

Future Research .................................................................................................................. 36

Conclusion .............................................................................................................................. 37

References ............................................................................................................................... 39


Abstract

Background: In order to remain healthy while performing at a high level, athletes must

exercise in a manner that is functional and translatable to the movement being produced

during sport. In order to accomplish this, exercises are often modified to meet the specific

demands of different sporting activities. Purpose: Although many studies have been

performed on several aspects of baseball pitching, few studies have focused on the submarine

pitcher. This pilot study investigated the difference in the activation patterns of select

muscles for subjects conducting two exercises: the cable retraction with external rotation

exercise and the modified version of the same exercise, which had been tailored to the

submarine pitcher. The following research was performed to advance the literature devoted

to the specific needs of submarine pitchers, and to raise awareness on the lack of literature

devoted to this style of throwing. Subjects: 16 healthy males ages 18-35 with previous high

school, college, and/or professional baseball experience participated in this study. Methods:

Each subject was observed performing five repetitions of the two exercises, while motion and

muscle activation patterns of the posterior deltoid, the infraspinatus, the middle trapezius,

and the lower trapezius were captured using the Qualisys Motion Capture System in

conjunction with the Noraxon SEMG system. Results: No significant differences were found

between the two exercises in terms of muscle activation patterns of the four muscles being

studied. A positive correlation was found between the muscle activation patterns of the two

exercises, indicating that both exercises may accomplish the same goal when it comes to

strengthening the four targeted muscles. A significant difference was found in the angle of

abduction in which peak muscle activation occurred for the posterior deltoid (13°), the

middle trapezius (17°), and lower trapezius (14°).


Introduction

The motion of throwing a baseball is widely considered one of the most dynamic

and demanding motions of the human body (Fleisig, Andrews, Dillman, & Escamilla,

1995). Overhead throwing places an extreme amount of stress on the structures of the

shoulder at end ranges of motion. When pitching, the internal torque of the shoulder at

the glenohumeral joint during arm acceleration has been reported to reach 10,000°/sec,

and the distraction force placed on the glenohumeral joint during arm deceleration has

been reported to reach 947 N (Pretz, 2004). As a result of the stresses that are placed on

the glenohumeral joint, and the inherent instability of the glenohumeral joint, pitching

accounts for 75% of all collegiate baseball injuries, with rotator cuff tendonitis being the

leading injury (Scher, Anderson, Weber, Bajorek, Rand, & Bey, 2010). In order to pitch a

baseball without causing injury to the upper extremity, the athlete must have adequate

strength, endurance, power, and neuromuscular control of the involved musculature. A

goal of sports medicine clinicians is to decrease the incidence of injury and maximize

performance by prescribing exercises that maximize these attributes (Carter, Kaminski,

Douex, Knight, & Richards, 2007). Therefore, it is imperative clinicians continue to

conduct research and determine the most effective methods of developing the upper

extremities of pitchers to prepare them to address the demands associated with throwing a

baseball. It is also vital to acknowledge the current lack of literature regarding

biomechanics and muscle activation of the unconventional baseball pitcher, specifically

the underhand or submarine pitcher, and appropriate training methods for these athletes.

Two factors determine an individual’s style of pitching. These include the lateral

trunk flexion angle at ball release and the amount of shoulder abduction of the throwing


arm at ball release (Truedson, Sexton, & Pettitt, 2012). There are four described styles of

pitching, which are loosely defined based on the factors stated above. These include the

overhand, sidearm, three-quarter, and submarine pitching styles (Figure 1). Pitchers are

labeled as overhand style pitchers when there is significant trunk side flexion

contralateral to the throwing arm and the throwing arm is angled vertically from the

ground during ball release. Sidearm pitchers are characterized by having no lateral trunk

flexion during release and roughly 90° of shoulder abduction which creates an arm angle

horizontal to the ground during ball release. The three-quarter pitcher is given this label

when the arm angle falls in-between these two categories, roughly three-quarters of the

way from a horizontal plane to a vertical plane, with minimal lateral trunk flexion

present. Submarine style pitchers are much less common than the other three styles. The

submarine pitcher laterally flexes the trunk towards the throwing side and abducts the

glenohumeral joint less than 90° during ball release. The resulting motion can give the

impression that the pitcher is throwing the ball in an underhand fashion (Matsuo, Takada,

Matsumoto & Saito, 2000; Whiteley, 2007). Submarine throwing mechanics allow for

the pitcher to release the baseball from the ball’s bottom two-thirds, thus creating a

downward or “topspin” on the ball, as apposed to the upward or “backspin” which is

created during an overhand pitch. This topspin is presumed to cause the fastball to sink

to a much greater degree than the other three styles of pitching (Pavlovich, 2011).


Figure 1. Types of Pitching Styles.

Adapted from “Biomechanical Characteristics of Sidearm and Underhand Baseball Pitching: Comparison with Those of Overhand and Three-quarter Pitching”, by Matsuo, T., Takada, Y., Matsumoto, T., Saito, K., 2000. Japanese Journal of Biomechanics in Sports and Exercise, 4, 245-252.

The researchers found limited evidence based research that focused on the

submarine pitcher; two studies have mentioned some differences in throwing

biomechanics for submarine pitchers when compared to overhand and three-quarter

pitchers (Matsuo et al., 2000; Matsuo et al., 2003). Matsuo et al. (2000) compared ball

release height, pitch velocity, lateral trunk tilt, glenohumeral abduction, and peak elbow

varus torque between two submarine pitchers and thirteen overhand and three-quarter

pitchers. The limited sample size did not allow for significant conclusions to be drawn

from this study, but it was noted that the submarine pitchers had a lower ball release

height, a lower pitch velocity, less glenohumeral abduction, decreased elbow varus

torque, and a lateral trunk tilt of 10-25° in the opposite direction of the lateral trunk tilt of

the overhand and three-quarter pitchers. In a later study by Matsuo et al. (2002), nine

overhand and three-quarter pitchers were compared to two submarine pitchers. Results

demonstrated a small decrease in peak wrist velocity, a large decrease in glenohumeral

abduction, and an increase in peak elbow varus torque for the submarine pitchers when

compared to the overhand and three-quarter pitchers. A limitation of the study was


sample size, as the sample was too small to provide researchers with statistically

significant information.

Phases of Throwing

Dillman, Fleisig, & Andrews (1993) split the overhead pitching motion up into six

phases. Regardless of style of pitching, the phases of the throwing motion remain the

same for all baseball pitchers. The biomechanics and kinematics of the conventional

baseball pitcher during these six phases have been extensively studied since the early

1980’s. Phase 1, known as the windup, begins when the pitcher steps backward with his

stride foot, rotates his body to the throwing side, shifts his weight to the supporting foot,

and lifts his stride foot. Phase 2, stride, is initiated when the stride foot is moved toward

the plate and the ball is brought out of the glove. As the stride foot moves closer to the

plate, the throwing arm is moved in a rhythmic down and then upward motion to ensure

that the upper and lower body are synchronized properly when the stride foot contacts the

ground. Phase 3, cocking, occurs once the stride foot contacts the ground. During this

phase, the hips rotate towards the plate, followed by trunk rotation and extension, elbow

flexion, and shoulder external rotation. Phase 4, arm acceleration, happens when maximal

external rotation is reached, and the arm begins to accelerate forward through shoulder

internal rotation, horizontal adduction, and elbow extension, until the ball is released.

Phase 5, arm deceleration, occurs when the posterior shoulder rotator cuff muscles

contract eccentrically to slow down the internal rotation torque created during the

acceleration phase. Elbow extension also happens during this phase. The 6th and final

phase, the follow-through, allows the pitcher to decelerate the forward momentum placed


on the entire body by shifting all weight to the stride foot and allowing the back foot to

leave the mound and fall in front of the stride foot (Dillman, Fleisig, & Andrews, 1993).

Tables 1 and 2 describe the biomechanics of the glenohumeral joint and the

muscle firing patterns that occur during the baseball pitch. With the exception of the

anterior deltoid, every muscle involved in glenohumeral and scapulothoracic motion

contracts to over 50% of their maximum voluntary isometric contractions at some phase

during the throwing motion, further illustrating the extremely dynamic nature of throwing

a pitch (see Table 1). Knowing this information can help offer clinicians an improved

sense of understanding of which muscles are activated in specific glenohumeral joint

positions during a pitch. Knowledge of this information could enable clinicians to

practice in an evidenced based manner, fostering accurate and efficient diagnoses and

treatments of baseball pitchers. Limited research was found to provide this kind of

information for the submarine pitcher to date; which could result in limited evidence

based clinical practices when training or treating the submarine pitcher. Continued

research focused on this style of throwing should be conducted, as the research findings

could potentially have a profound impact on how submarine pitchers are to be treated

compared to the rest of the population of pitchers.


Table 1 % Maximum Muscle Activation of the Shoulder Muscles During Each Phase of Pitching

Muscles Wind Up

%MVIC

Stride %MVIC

Arm Cocking %MVIC

Arm Acceleration

%MVIC

Arm Deceleration

%MVIC

Follow Through %MVIC

Upper Traps 18 σ16 64 σ53 37 σ29 69 σ31 53 σ22 14 σ12 Middle Traps 7 σ5 43 σ22 51 σ24 71 σ32 35 σ17 15 σ14 Lower Traps 13 σ12 39 σ30 38 σ29 76 σ55 78 σ33 25 σ15 Serratus Anterior 6th Rib

14 σ12 44 σ35 69 σ32 60 σ53 51 σ30 32 σ18

Serratus Anterior 4th Rib

20 σ20 40 σ22 106 σ56 50 σ46 34 σ7 41 σ24

Rhomboids 7 σ8 35 σ21 41 σ26 71 σ35 45 σ28 14 σ20 Levator Scapula

0 σ5 35 σ14 72 σ54 70 σ29 33 σ10 14 σ13

Anterior Deltoid

15 σ12 40 σ20 28 σ30 27 σ19 47 σ34 21 σ16

Middle Deltoid

9 σ8 44 σ19 12 σ17 36 σ22 59 σ19 16 σ13

Posterior Deltoid

6 σ9 42 σ26 28 σ27 68 σ66 60 σ28 13 σ11

Supraspinatus 13 σ12 60 σ31 12 σ17 51 σ46 39 σ43 10 σ9 Infraspinatus 11 σ9 30 σ18 73 σ34 31 σ28 37 σ20 20 σ16 Lower Subscapularis

7 σ9 26 σ22 62 σ19 56 σ31 41 σ23 25 σ18

Upper Subscapularis

7 σ8 37 σ26 99 σ55 115 σ82 60 σ36 16 σ15

Teres Minor 5 σ6 23 σ15 71 σ42 54 σ50 84 σ52 25 σ21 Latissimus Dorsi

12 σ10 33 σ33 50 σ37 88 σ53 59 σ35 24 σ18

Pectoralis Major

6 σ6 11 σ13 56 σ27 54 σ24 29 σ18 31 σ21

Biceps Brachii

4 σ6 22 σ14 26 σ20 20 σ16 44 σ32 16 σ14

Triceps Brachii

8 σ9 17 σ17 37 σ32 89 σ40 54 σ23 22 σ18

σ – Standard Deviation %MVIC – percent of maximum voluntary isometric contraction (DiGiovine, Jobe, Pink, & Perry, 1992)


Table 2 Joint Position of the Shoulder During Four Phases of Pitching

GH Joint Positioning Start to Finish

Arm Cocking Arm Acceleration

Arm Deceleration

Follow Through

Rotation 53°ER-178°ER

178°ER-105°ER

105°ER-0°ER 0°ER-30°ER

Ab/adduction 90°AB-100°AB

100°AB-95°AB

95°AB-100°AB

100°AB-95°AD

Horizontal Ab/adduction

30°HAB-14°HAD

14°HAD-0°HAD

0°HAD-30°HAD

30°AB-65°HAD

ER – external rotation AB – abduction AD – adduction HAB – horizontal abduction HAD – horizontal adduction (Dillman, Fleisig, & Andrews, 1993) Electromyography

Electromyography (EMG) is a technique that measures electrical activity during

the contraction and relaxation phases of muscles being tested (Hogrel, 2005). It is used to

study normal muscular function during patterns of movements and positions in the realm

of sports medicine and occupational and physical therapies (Clarys, Scafoglieri,

Tresignie, Reilly, & Von Roy, 2010). Electromyographic analysis of the throwing

shoulder during pitching and during exercise provides information for clinicians to

develop exercises and exercise programs that enhance the preventive and rehabilitative

arenas of sports medicine. Knowledge of the electrical activity of muscles during assorted

exercises allows clinicians to choose exercises that most effectively challenge target

muscles or groups of muscles when preparing a strengthening or rehabilitation program

(Hancock and Hawkins, 1996). There are two major types of EMG analysis, needle

EMG and surface EMG (SEMG). SEMG is a noninvasive technique, which measures

electrical activity of muscles through electrodes that are placed directly on the skin


(Hogrel, 2005). Needle EMG assesses the same electrical activity through thin needle

electrodes, which are inserted through the skin and directly into the belly of the muscle

being assessed. Unlike the needle electrode, which penetrates the muscular tissue and

permits the detection of the virtually undistorted myoelectric signal, surface electrodes

detect the signal only after filtering through all the biological tissues between the many

signal sources (i.e. the activated muscle fibers) as well as filtering through the interaction

of other electrodes placed on the skin. Because of this, the validity of the SEMG has been

questioned, and tested in comparison to needle EMG. One study observed the accuracy of

SEMG signals coming from the vastus intermedius muscle compared to needle EMG

signal of the same muscle. The researchers found no significant differences between the

readings of the invasive procedure (needle EMG) and non-invasive procedure (SEMG)

when testing the vastus intermedius muscle. They concluded that SEMG is a valid

instrument that can be used to accurately determine the electrical activity of select

muscles. This same study acknowledged that proper electrode placement is vital to

obtaining accurate and valid SEMG readings, especially with muscles that have very

small superficial areas (Watanabe & Akima, 2011). Another study was conducted to

determine the reliability of SEMG readings for upper extremity muscles. This study was

conducted with 30 healthy subjects participating in 10 different exercises to discover

which high-intensity exercises produce the greatest level of SEMG activity of the

trapezius and serratus anterior muscles. The researchers found the reliability of the

SEMG recordings to be 0.91- 0.98 when muscles worked as prime movers, with the

exclusion of the upper trapezius where reliability was found to be 0.81 – 0.89, concluding

that using SEMG to detect the muscle activity of upper extremity muscles is highly to


moderately highly reliable (Ekstrom, Donatelli and Soderburg, 2003).

SEMG does have some accuracy concerns, which are mostly a result of the

techniques employed by examiners. The conduction properties of biological tissues may

cause interference; therefore skin preparation, electrode placement, and measurement

protocols must be performed consistently to gather data that is accurate and consistent

(Hogrel, 2005). There is limited research available that has been focused on the

relationship of human body composition, the anatomical variation of cutaneous and

subcutaneous adipose patterning, and the effects they have on the accuracy of SEMG

readings (Clarys et al., 2010). However, research has described the best way to prepare

the skin for electrode placement. (1) If the skin is dry, place a moist tissue soaked with

water over the target area. (2) If the skin is oily, rub it with alcohol. (3) Whatever the

condition of the skin, it is important to keep the skin impedance as low as possible by

rubbing it with a cotton swab to remove dead cells. (4) Rub in conductive gel and dry the

skin carefully where the electrode will be placed (Blanc and Dimanico, 2010).

The noninvasiveness and decrease in risk of injury made SEMG the technique of

choice for this study as opposed to needle EMG. The SEMG technique can also expedite

the research process due to the simplistic and efficient manner to which the electrodes

can be applied to the subjects.

Motion Analysis

The addition of motion analysis technology to the research and clinical arenas

made the study of human motion more accessible while maintaining objectivity (Vander

Linden, Carison, & Hubbard, 1992). Several motion analysis systems use a computer

based software system in combination with cameras designed to capture the signals


transmitted from special sensors strategically placed on the subject resulting in the

capture of human motion providing an objective picture of joint kinematics in real time

(Tucker et al., 2008). The use of three-dimensional imaging is an invaluable tool for

quantifiable evaluation of movement in all planes of motion (Murphy, Sunnerhagen,

Johnels, & Willen, 2006). Surface electromyography and motion analysis technology can

be used in conjunction as a means to measure muscle activation via SEMG in real-time

with accurate knowledge of joint motion and joint position during muscle action.

Purpose

It is common in physical therapy for exercises to be modified to meet the needs of

each individual patient. An article written by Truedson, Sexton, and Pettitt (2012)

proposed that exercises should be tailored to meet the sport specific needs of submarine

pitchers. To the knowledge of the researchers, this is the only published article that

discussed this topic. It described two exercises commonly used for strengthening and

rehabilitation: the kneeling deceleration exercise and the cable retraction with external

rotation (ER) exercise. It explained how these exercises were modified to meet the needs

of the submarine pitcher. This raised the question of whether or not the modifications are

successful at altering muscle recruitment patterns to make these exercises more beneficial

to this population of pitchers. The exercise studied during this experiment was the cable

retraction with external rotation (ER). The purpose of this study was to determine if

muscle recruitment patterns differ during the modified cable retraction with ER exercise

compared to when the exercise is conducted in the traditional manner.


Research Question

Was there a difference in muscle activation for patients conducting the modified

cable retraction with ER exercise when compared to performing the traditional method of

this exercise?

Hypothesis

In order to test the research question, the following hypothesis was developed.

HO: There was no significant difference in muscle recruitment patterns when comparing

the modified form of the exercise to the traditional form of the exercise.

HA: There was a significant difference in muscle recruitment patterns when comparing

the two methods of the exercise.

Methods

This study was a pilot study intended to address two major objectives. The

researchers aimed to determine if there were differences in muscle activation between

two similar upper extremity exercises, and also aimed to raise awareness of the lack of

literature that exists on submarine pitchers and to stimulate interest in this subject. The

independent variables in this study were the two different exercises, the cable retraction

with external rotation exercises, and the modified cable retraction with external rotation

exercise. The dependent variables were the muscle activity readings of each individual

muscle and the angle of glenohumeral abduction at peak EMG activity. The particular

muscles being observed included; the middle trapezius, lower trapezius, posterior deltoid,

and infraspinatus muscles. There were several reasons why these muscles were observed.

For one, these are superficial muscles that can readily be studied using SEMG (Bitter el

al., 2007; Kibler, Sciascia, Uhi, Tambay, & Cunningham, 2008; Marta et al., 2013).


Another reason is that the traditional method of the cable retraction with ER exercise is

designed to target the middle trapezius and rhomboids, the lower trapezius, and the

posterior rotator cuff (Paine & Voight, 2013). The posterior deltoid was studied due to its

high MVIC readings during the deceleration phase of throwing, as well as its high MVIC

readings during exercises involving horizontal abduction with the humerus in external

rotation (DiGiovine et al., 2007; Marta et al., 2013). The infraspinatus was studied due to

its importance as a dynamic stabilizer of the glenohumeral joint during the throwing

motion. One of the major causes for shoulder injury in the overhand thrower is muscle

imbalance between the internal rotators of the glenohumeral joint (subscapularis,

pectoralis major, latissimus dorsi, and teres major) that forcefully internally rotate the

humerus during arm acceleration, and the external rotators (infraspinatus and teres minor)

that work to overcome the internal rotation torque to decelerate the humerus. Due to the

role of the infraspinatus as a decelerator and major dynamic stabilizer of the

glenohumeral joint, it is important that strengthening and rehabilitative exercises be

conducted to target this muscle. Weakness of the infraspinatus can cause an increase in

humeral head translation during throwing, an increase the risk of subluxation of the

humeral head, and can lead to shoulder pain, impairment, and disability. Along with

glenohumeral stability, throwing also requires a significant amount of scapular stability.

The middle and lower trapezius musculature were studied due to their roles as scapular

stabilizers. These muscles support and control the scapula in an effort to provide a stable

glenoid, which enables the glenohumeral muscles to maintain optimal length-tension

relationships during throwing (Donatelli, et al., 2000).


Subjects

Sixteen male volunteers were recruited from the student body of a local university

and from local minor league baseball teams by means of convenience sampling. The

inclusion criteria consisted of males ages 18-35, a history of participation in the sport of

baseball at least at the high school level, no history of elbow or shoulder surgery in the

past 2 years, no electrode adhesive allergies, no history of shoulder instability, no history

of shoulder or elbow pain in the past 6 months, no participation is shoulder or elbow

rehabilitation is the past 6 months, and no participation in activities that could fatigue the

upper extremities 24 hours prior to the study. Therefore, the exclusion criteria consisted

of being outside the age range of 18-35, female, no history of participation in baseball at

least a the high school level, history of elbow or shoulder surgery in the past 2 years,

electrode adhesive allergies, history of shoulder instability, history of shoulder or elbow

pain or rehab in the past 6 months, failure to refrain from upper extremity fatiguing

exercises 24 hours prior to the study, unsafe resting heart-rate or blood pressure on the

day of the study, and any other contraindications to exercise as indicated on the medical

screening form or observed by the researchers. No females were included due to the fact

most baseball pitchers are male, hence male only participation provides a more accurate

sample of the population being studied. To ensure the level of wellness of the research

participants, all members involved filled out a PAR-Q Health/Medical History

Questionnaire. Participants were instructed not to participate in any activities that may

fatigue the muscles of the upper extremity at least 24 hours before testing. To ensure the

participants followed the research protocol of no activities that would fatigue the muscles

of the shoulder, all participants filled out an activity log the day before the study, which


was reviewed by the researchers prior to data collection. The participants provided

written informed consent and the Florida Gulf Coast University Institutional Review

Board approved this study.

Instrumentation

SEMG via the Noraxon system and the Qualisys motion capture system were

integrated together to establish a means to measure muscle activation while gaining

insight to the position of the upper extremity and the line of action of the targeted

muscles. The combination of the two systems provided a failsafe during data collection

and analysis. The incorporation of the two systems allowed the researchers to eliminate

erroneous data collected when an exercise was performed in the wrong plane. By

identifying exercises performed in the proper manner and eliminating those that were not,

the researchers eliminated a potential skew of the data and facilitated a more accurate

depiction of how the two exercises compared to one another.

The researchers followed the electrode placement utilized by Kibler, Sciascia,

Uhi, Tambay, and Cunningham (2008) who performed electromyographic analysis of

specific exercises for scapular control in early phases of shoulder rehabilitation. The

lower trapezius electrodes were located 2 cm apart at an oblique angle, 5 cm down from

the scapular spine, and outside the medial border of the scapula. The posterior deltoid

electrodes were positioned 2 cm apart, 2 cm inferior to the lateral border of the spine of

the scapula, and located at an oblique direction toward the humerus, running parallel with

muscle fiber direction. The middle trapezius electrodes were located between the spine of

the scapula and the spinous processes of the vertebrae at the same level, in accordance

with Marta et al. (2013). Placement of the infraspinatus muscle electrode was performed


in accordance with a study performed by Bitter el al. (2007) who studied the

contributions of the infraspinatus and deltoid during shoulder external rotation of subjects

with healthy shoulders. The infraspinatus electrode was positioned 4 cm below and

parallel to the scapular spine over the infrascapular fossa.

A trained practitioner placed Qualisys soft markers appropriately on each

landmark. Markers were placed on the acromions, medial and lateral epicondyles of the

humerus, radial and ulnar styloid processes, the sternum, the iliac crests, the posterior

superior iliac spines and the anterior superior iliac spines, the greater trochanters, the

medial and lateral femoral epicondyles, the medial and lateral malleoli, the calcaneous,

and the base of the 5th metatarsals. Cluster sets of markers were placed on the arms,

forearms, the lower back, the thighs, and the lower legs.

The complex movement of the exercises observed in this study provided some

challenges due to the difficulty of capturing the signal from each marker through the

entire motion of the activity. Therefore, it was imperative that the researchers in this

study established proper marker placement to ensure the capture of motion being

transmitted from all points of reference. For the purposes of this study, a segment link

model was developed through digitization of joint centers of the shoulder and

sternojugular notch.

Procedure

Each data collection session began with a system calibration of the Qualisys

motion capture system to ensure accurate and consistent data capture. Upon arrival, each

participant provided written informed consent. Each participant was asked to complete

the PAR-Q Health/Medical History Questionnaire while the researchers reviewed his 24-


hour activity log. Next, the participant’s resting heart rate and blood pressure were taken

to ensure the subject was safe to exercise. Each participant was educated on the research

procedures, and instructed how to perform the traditional and modified cable retraction

with ER exercises for shoulder rehabilitation and strengthening. Once the researchers

determined that it was safe for the subjects to participate the following scientific

procedures were performed. The skin was prepared for electrode placement and SEMG

electrodes were placed on each participant in accordance with the instructions outlined in

the methods section. Following electrode placement, each participant completed the

upper body dynamic warm-up that included trunk rotations, arm circles, arm swings, and

pendulums. The maximum voluntary isometric contractions (MVICs) of the

infraspinatus, lower and middle trapezius, and posterior deltoid muscles of each subject

were collected for normalization of the EMG data collected during this study. The

MVICs were collected utilizing standard manual muscle testing (MMT) techniques

described by Kendall, McCreary, Provance, Rodgers, and Romani (2005). Two

researchers performed MVIC capture; one researcher performed the muscle testing

procedure while the second researcher simultaneously captured the MVIC data via the

integrated Qualisys/Noraxon system. For each muscle being tested, the subjects were

placed in the appropriate position and the researcher applied a force through the upper

extremity of the subject for five seconds. Three trials were preformed for each muscle

tested. Data for the MVICs were collected from the trial that elicited the greatest MVIC

for each respected muscle. These MVICs were measured to provide a reference point for

the electrical activity of each muscle being studied. Within each subject, the EMG values

for each muscle during each exercise were normalized as a percentage of the highest


EMG value produced by that muscle during a MVIC. The EMG data for the exercises

were then expressed as percent maximum voluntary isometric contraction (% MVIC).

The position of the researcher and subject while testing each muscle is described in Table

3.

Table 3 Manual Muscle Testing Positions for MVIC Collection

Muscle Subject Position Researcher Hand Positioning

Force Application

Infraspinatus Prone with humerus abducted 90°, externally

rotated 80°, and elbow flexed 90°

Fixation hand: Cradling the humerus

near the elbow Pressure hand: Distal

forearm

Downward through the forearm

Middle Trapezius

Prone with the humerus at the edge of the table

abducted to 90° and the elbow flexed 90°. The

scapula is retracted.

Fixation hand: Contralateral scapula Pressure hand: Distal

humerus

Downward toward the floor

Posterior Deltoid

Prone with humerus abducted 90°and slightly

externally rotated and elbow flexed 90°

Fixation hand: Stabilizing the

scapula Pressure hand:

Posterolateral surface of the humerus

Obliquely downward and midway between

adduction and horizontal adduction

Lower Trapezius

Prone with humerus abducted 140° and externally rotated

Fixation hand: On the opposite scapular

area to prevent trunk rotation

Pressure hand: Distal forearm

Downward through the forearm

Once MVIC collection was complete, each subject was given a three-minute rest

period, in accordance with Richmond and Godard (2004), who found that subjects were

able to recover fully from the previous set of exercises when given a three-minute rest

period. During the rest period, Qualisys motion analysis markers were positioned on the


individual as described in the previous section. Next, each subject completed two model

captures: a static model and a dynamic model. Then, the subjects were re-educated on

how to conduct the exercises being tested, and each participant performed trial repetitions

of the exercises until the researchers were assured that the participant could conduct the

exercise correctly. Finally, each subject completed one set of 5 repetitions of the

traditional exercise. Each repetition was performed in four seconds (two seconds for the

concentric phase and two seconds for the eccentric phase) and in rhythm with a

metronome set at 90 beats per minute. The metronome was utilized to ensure that the

rhythm and speed in which the exercise was conducted was universal to all participants,

decreasing the variability of the muscle activation patterns between subjects. The

participant then rested for three minutes while the next exercise was explained and

demonstrated. Then the participant demonstrated the proper exercise technique and then

completed five repetitions of the modified exercise in the same manner as the previous

exercise. Data were captured for all five repetitions of each exercise. Repetitions two

through four were utilized from the data set and analyzed for the results of this study.

Exercise Descriptions

The exercises involved in the study were the cable retraction with external

rotation exercise and a modified version of the same exercise. The exercise was

performed using a cable pulley system set to a resistance of five pounds for each

participant. The resistance was set to five pounds because each participant was able to

perform multiple repetitions of the exercises at this weight with proper form and

technique.


Cable retraction with external rotation. The cable retraction with external

rotation was performed using a cable column weight system with the handle at the height

of the participants mid tibia. The participant stood in front of the cable system with his

feet staggered in such a way in which he simulated the stance of a pitcher at ball release.

He then grasped the handle that was attached to the cable with the dominant hand. The

starting position of the shoulder and elbow consisted of slight glenohumeral internal

rotation, glenohumeral abduction of 90°, glenohumeral horizontal adduction of 20°, and

elbow flexion of approximately 20°. The trunk started in a forward flexed position. The

concentric phase of the exercise consisted of simultaneous trunk extension, glenohumeral

external rotation, horizontal abduction, scapular retraction, and slight elbow flexion. The

ending position of the exercise was full external rotation and horizontal abduction of the

glenohumeral joint, retraction of the scapula, and 70° of elbow flexion. The patient then

used an eccentric contraction to slowly reverse the motion until the arm has returned to

the starting position (Paine & Voight, 2013). The exercise is shown in figure 2.


Figure 2. The Cable Retraction With External Rotation Exercise

Modified cable retraction with external rotation. The modified version of this

exercise, described by Truedson, Sexton, and Pettitt (2012), was more closely related to

the act of throwing a submarine pitch. The participant stood parallel to the cable machine

with a wide base of support. The starting position of the exercise corresponded to the

position of the submarine pitcher at the moment of ball release. This required the

patient’s arm to be horizontally adducted and extended and the trunk to be flexed over the

front leg. The patient then retracted the scapula while extending the trunk and externally

rotating the shoulder. Once the patient was standing with the trunk extended, the shoulder

externally rotated and abducted to 30°, and the elbow slightly flexed, the patient

performed an eccentric contraction and allowed his body to move in the motion of a

submarine pitch until the patient returned to the starting position. The exercise is shown

in figure 3.


Figure 3. The Modified Cable Retraction With External Rotation Exercise

Data Analysis

The data from this study compared peak muscle activity of the muscles being

studied between the two exercises described above. It also compared the angles of

abduction of the glenohumeral joint for when each muscle reached peak activity between

the two exercises. The data were recorded using the 3-D motion analysis system and

Visual 3D© in conjunction with the Noraxon surface EMG system. The IBM SPSS

statistics GRAD PACK 22.0 base program was used to analyze the data. A Paired

samples test was used to determine differences in peak muscle activity between the two

exercises, as well as the difference in the angle of glenohumeral abduction at the time of

peak muscle activity for the two exercises. A Pearson correlation coefficient was used to

determine if correlations in peak muscle activity were present between the two exercises,

as well as whether or not correlations in the angle of glenohumeral abduction at the time

of peak muscle activity for the two exercises were present.

Results

Data analysis revealed statistically significant correlations between the peak

muscle activities of the four select muscles when observing the SEMG of the two


exercises. Table 4 represents the results of the peak muscle activity of each muscle during

each exercise, normalized as a percentage of the MVIC of each muscle being tested.

During the traditional exercise, the peak muscle activity of the posterior deltoid was 1.1%

of its MVIC, the peak muscle activity of the infraspinatus was .77% of its MVIC, the

peak muscle activity of the middle trapezius was 1.5% of its MVIC, and the peak muscle

activity of the lower trapezius was .91% of its MVIC. During the modified version of the

exercise, the peak muscle activity of the posterior deltoid was 1.1% of its MVIC, the peak

muscle activity of the infraspinatus was 1.2% of its MVIC, the peak muscle activity of

the middle trapezius was 1.5% of its MVIC, and the peak muscle activity of the lower

trapezius was .82% of its MVIC (Table 4).

A Pearson correlation coefficient was calculated for the relationship between

participant’s of the maximum muscle activation achieved (normalized with % MVIC) for

Table 4 Peak Muscle Activity During Each Exercise (Paired Samples Statistics) Mean

(%MVIC) N Std.

Deviation Std. Error

Mean Pair 1 M Posterior Deltoid

MAX 1.0559 12 1.0245 .29574

T Posterior Deltoid MAX

1.1309 12 1.2972 .37447

Pair 2 M Infraspinatus MAX 1.2025 12 1.4493 .41839 T Infraspinatus MAX .76956 12 .40985 .11831

Pair 3 M Mid Trap MAX 1.5093 12 1.1971 .34558 T Mid Trap MAX 1.4802 12 .88189 .25458

Pair 4 M Low Trap MAX .82168 12 .52659 .15201 T Low Trap MAX .90978 12 .56768 .16387

M – modified cable retraction with external rotation exercise T – traditional cable retraction with external rotation exercise MAX – maximum muscle activity


the posterior deltoid, infraspinatus, middle trapezius, and lower trapezius during the

traditional and modified versions of the cable retraction with ER exercise. The

researchers found a strong positive correlation for peak muscle activation of the posterior

deltoid (r(10) = .913, p < .001), infraspinatus (r(10) = .749, p < .001), middle trapezius

(r(10) = .765, p < .001), and lower trapezius (r(10) = .850, p < .001) when comparing the

two exercises, indicating a significant relationship between peak muscle activation of

these four muscles during the two exercises. Both exercises produced statistically

significant correlations of peak activation of the four muscles being studied (Table 5 and

Table 6).

Table 5 Correlations in Peak Muscle Activity During Both Exercises (Paired Samples Correlations) N Correlation Sig. Pair 1 M Posterior Deltoid MAX & T Posterior Deltoid

MAX 12 .913 .000

Pair 2 M Infraspinatus MAX & T Infraspinatus MAX 12 .749 .005 Pair 3 M Mid Trap MAX & T Mid Trap MAX 12 .765 .004 Pair 4 M Low Trap MAX & T Low Trap MAX 12 .850 .000 M – modified cable retraction with external rotation exercise T – traditional cable retraction with external rotation exercise MAX – maximum muscle activity


Table 6 Correlations in Peak Muscle Activity During Both Exercises T

Posterior Deltoid MAX

T Infraspinatus MAX

T Mid Trap MAX

T Low Trap MAX

M Posterior Deltoid MAX

Pearson Correlation

.913** .172 .184 .249

Sig. (2-tailed)

.000 .593 .568 .435

N 12 12 12 12 M Infraspinatus MAX

Pearson Correlation

.784** .749** .329 .593*

Sig. (2-tailed)

.003 .005 .297 .042

N 12 12 12 12 M Mid Trap MAX Pearson

Correlation .306 .620* .765** .549

Sig. (2-tailed)

.334 .031 .004 .064

N 12 12 12 12 M Low Trap MAX Pearson

Correlation .390 .590* .732** .850**

Sig. (2-tailed)

.210 .043 .007 .000

N 12 12 12 12

**. Correlation is significant at the 0.01 level (2-tailed). *. Correlation is significant at the 0.05 level (2-tailed). M – modified cable retraction with external rotation exercise T – traditional cable retraction with external rotation exercise MAX – maximum muscle activity

A paired-samples t test was calculated to compare the mean difference of the peak

%MVICs of the muscles being studied during each exercise. The mean difference peak


%MVIC between the two exercises was .0749 (sd = .5527) for the posterior deltoid,

.4329 (sd = 1.174) for the infraspinatus, .02914 (sd = .7711) for the middle trapezius, and

.08810 (sd = .3021) for the lower trapezius. The results indicated that there was no

significant difference between average peak muscle activation between the two exercises

with the four muscles being studied (Table 7).

A paired-samples t test was calculated to compare the mean difference of the

glenohumeral abduction angle of the peak muscle activity of the muscles being studied

during each exercise. The angle of abduction was significantly less during the modified

exercise for the posterior deltoid (13.17°, sd = 13.66°), middle trapezius (17.45°, sd =

24.04°), and lower trapezius (14.10°, sd = 18.01°) (Table 8).

A Pearson correlation coefficient was calculated examining the relationship

between the glenohumeral abduction angles during the peak muscle activity of the

muscles being studied during each exercise. No strong or weak correlations were found

between the two exercises when comparing where peak muscle activation is occurring in

terms of glenohumeral abduction angles. This indicated that peak muscle activity of the

muscles being studied did not occur at the same level of glenohumeral abduction during

the modified version of the exercise, as it did during the traditional version of the exercise

(Table 9).


Table 7 Mean Difference in Peak Muscle Activity Between the Modified and Traditional Exercises (Paired Samples Test) Paired Differences t df Sig

. (2-tailed)

Mean Std. Deviation

Std. Error Mean

95% Confidence

Interval of the Difference

Lower

Upper

Pair 1

M Post Delt MAX - T Post Delt MAX

-.0749 .553 .160 -.426 .276 -.470 11 .648

Pair 2

M Infra MAX - T Infra MAX

.433 1.17 .339 -.313 1.18 1.28 11 .228

Pair 3

M Mid Trap MAX - T Mid Trap MAX

.0291 .771 .223 -.461 .519 .131 11 .898

Pair 4

M Low Trap MAX - T Low Trap MAX

-.0881 .302 .0872 -.280 .104 -1.01 11 .334

M – modified cable retraction with external rotation exercise T – traditional cable retraction with external rotation exercise MAX – maximum muscle activity Post Delt – Posterior Deltoid, Infra – Infraspinatus, Mid Trap – Middle Trapezius, Low Trap – Lower Trapezius


Table 8 The Mean Difference in the Angle of Glenohumeral Abduction During Peak Muscle Activity Between the Modified and Traditional Exercises Paired Differences t df Sig.

(2-tailed)

Mean

Std. Deviation

Std. Error Mea

n

95% Confidence Interval of the

Difference Lower Upper

Pair 1

M Post Delt Y – T Post Delt Y

-13.2 13.7 3.94 -21.8 -4.49 -3.34 11 .007

Pair 2

M Infra Y – T Infra Y

-5.78 14.0 4.04 -14.7 3.11 -1.43 11 .180

Pair 3

M Mid Trap Y – T Mid Trap Y

-17.4 24.0 6.94 -32.7 -2.17 -2.51 11 .029

Pair 4

M Low Trap Y – T Low Trap

-14.1 18.0 5.20 -25.5 -2.66 -2.71 11 .020

M – modified cable retraction with external rotation exercise T – traditional cable retraction with external rotation exercise MAX – maximum muscle activity Post Delt – Posterior Deltoid, Infra – Infraspinatus, Mid Trap – Middle Trapezius, Low Trap – Lower Trapezius


Table 9 Correlation of Glenohumeral Abduction Angle During Peak Muscle Activity T Posterior

Deltoid Y T

Infraspinatus Y

T Mid Trap Y

T Low Trap

Y M Posterior Deltoid Y

Pearson Correlation

-.259 .175 -.340 -.334

Sig. (2-tailed)

.415 .587 .280 .289

N 12 12 12 12 M Infraspinatus Y

Pearson Correlation

-.451 .206 .147 -.285

Sig. (2-tailed)

.141 .521 .649 .370

N 12 12 12 12 M Mid Trap Y Pearson

Correlation -.152 -.062 .018 .060

Sig. (2-tailed)

.636 .849 .956 .853

N 12 12 12 12 M Low Trap Y Pearson

Correlation -.236 .229 -.218 -.217

Sig. (2-tailed)

.461 .474 .496 .498

N 12 12 12 12 **. Correlation is significant at the 0.01 level (2-tailed). M – modified cable retraction with external rotation exercise T – traditional cable retraction with external rotation exercise N – number or subjects Y – plane in which motion is occurring

Discussion

The purpose of this study was to determine if differences in were present muscle

activation patterns of select muscles for subjects who conducted two exercises: the cable

retraction with external rotation exercise, and the modified version that had been tailored


to meet the demands of the submarine pitcher. As indicated in the results, no significant

differences were found between the two exercises in terms of muscle activation patterns

of the four muscles being studied, which supported the null hypothesis. However, there

was a strong correlation between peak muscle activation of the posterior deltoid,

infraspinatus, and middle and upper trapezius muscles during the two exercises (Tables

5&6). Truedson, Sexton, and Pettitt (2012) stated that in order to remain healthy while

performing at a high level, athletes must exercise in a manner that is functional and

translatable to the movement being produced during sport. The researchers’ findings in

this study indicated that the modified exercise was able to target the same shoulder

musculature as the traditional exercise, while the athlete was performing a functional

movement pattern that is concordant with the motion performed by the submarine

pitcher. Therefore, it may be more beneficial for the submarine pitcher to train using the

modified version of the exercise.

The researchers found differences in the glenohumeral abduction angle in which

peak muscle activation was occurring when the two exercises were compared. The angle

of abduction when peak muscle activity was occurring was significantly less during the

modified exercise (Table 9). A significant difference was found in the angle of abduction

in which peak muscle activation occurred for the posterior deltoid (13°), the middle

trapezius (17°), and lower trapezius (14°). This may warrant the utilization of this

exercise because it allowed for peak muscle activation to occur in a position that was less

likely to cause subacromial impingement than the traditional exercise. Park et al. (2003)

stated that when analyzing baseball pitchers, impingement occurs with the arm in 90° or

greater abduction, with movement into an internally rotated and horizontally adducted


position. Based on the results of this study, the modified cable retraction with external

rotation exercise is able to be used to train the posterior deltoid, middle trapezius, and

lower trapezius as efficiently as the traditional version, while decreasing the risk of an

exercise acquired impingement syndrome in the shoulder.

In summary, there were no differences found between the two exercises in terms

of peak muscle activation of the posterior deltoid, infraspinatus, and middle & lower

trapezius. However, there was a strong correlation between peak muscle activation of the

muscles being tested, as well as a significant difference in the angle of abduction in

which peak muscle activation occurred when performing the modified cable retraction

with external rotation exercise compared to the traditional exercise. The researchers of

this study deem that modifying the traditional exercise is unnecessary if the clinician is

targeting the four muscles tested in this study. However, it may be beneficial to the

submarine pitcher to perform the modified version of the exercise because it replicates

the submarine throwing motion while still exercising the targeted muscles as efficiently

and the traditional exercise. There is no evidence present to suggest that this exercise

meets the physiological demands of this activity, due to the currently existing gap in the

literature on the biomechanics and muscle activation patterns of the shoulder during a

submarine pitch.

Limitations

All aspects of this study were attempted to be controlled by the researchers.

However, there were still limitations to the study. The sample size of sixteen participants

is adequate for a pilot study, but it was too small for strong conclusions to be drawn from

this study. Also, each participant conducted the two exercises differently. The exercises


involved multiple joint motions and were complex in nature. They were difficult to

perform for some individuals, and no two participants performed each exercise exactly

the same. However, all subjects were able to perform the exercises adequately and within

the scope of this study. Extraneous variables could have affected the validity of the

results of the study and include the fact that two different clinicians were used to place

the Qualisys soft markers on the participants, and the Noraxon electrodes were placed on

each participant by means of vision and palpation.

Future Research

As previously stated, this study was meant to be a pilot study to increase the

scholarly interest in the submarine pitcher, and how exercises may be modified to create

more efficient training and rehabilitation routines for them. An important area in baseball

research that is currently lacking is the biomechanics and kinematics of the submarine

pitcher. Future research needs to be performed to determine the biomechanics and muscle

activation patterns of the submarine pitcher in order to develop a better understanding of

the physiological demands of this activity. This knowledge will aid clinicians in

developing appropriate exercise programs and techniques to train these athletes utilizing

evidenced based practices focused on function. Currently, when utilizing the modified

version of the cable retraction exercise, the thought that the exercise is targeting the

muscles needed for decelerating the arm of a submarine pitcher it is base solely on

theory, as there is inadequate evidence on the true physiological demands placed on the

soft tissues of these pitchers. One element of difference when comparing the throwing

motion of submarine pitcher and traditional is that there is a significant difference in the

angle abduction of the glenohumeral joint. Consequently, the forces applied the shoulder


during this activity must be researched to better serve this athletic population in order to

better train or rehabilitate these throwers through evidence based practice.

Conclusion

There are over thirty pitchers currently in professional baseball that are

considered to be submarine pitchers. Expert opinion theorizes that it is more popular in

the collegiate setting due to the effectiveness it can have on younger hitters who have

never seen pitching from this arm angle. This style of pitching, although rare, is prevalent

enough to warrant investigation into the biomechanics of the motion as well as the stress

it places on the shoulder, elbow, and spine. Although there is limited research focused on

the difference in stresses placed on the body between the overhand thrower and the

submarine thrower, clinicians must still be able to train and rehabilitate submarine

pitchers effectively. The results of the present study demonstrated that the modified cable

retraction with external rotation exercise could be as effective at training the posterior

shoulder musculature as the traditional version of the exercise, while training the athlete

in a motion functional to the athlete’s style of pitching. This is important, because in

order to decelerate the arm during throwing and prevent injury to the shoulder, the

posterior deltoid, infraspinatus, middle trapezius, and lower trapezius (along with several

other muscles) must be adequately trained to safely counteract the velocity of the

throwing arm, as well as stabilize the scapula (DiGiovine, Jobe, Pink, & Perry, 1992).

The findings of this study support the theory that the cable retraction with external

rotation exercise can be modified to meet the specific needs of the submarine pitcher,

without decreasing the effectiveness of the exercise, while also exercising the shoulder in

a position that is less likely to cause impingement syndrome. However, without proper


knowledge of what is occurring within the body during the submarine pitch, clinicians

cannot be positive that modifying exercises for submarine pitchers is more beneficial than

traditional pitching exercises.


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