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 Submarine Pitchers 5
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°). Submarine Pitchers 6
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 Submarine Pitchers 7 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).
Submarine Pitchers 8
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 Submarine Pitchers 9 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 Submarine Pitchers 10 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.
Submarine Pitchers 11
Table 1
% Maximum Muscle Activation of the Shoulder Muscles During Each Phase of Pitching Muscles Wind Stride Arm Arm Arm Follow Up %MVIC Cocking Acceleration Deceleration Through %MVIC %MVIC %MVIC %MVIC %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 14 σ12 44 σ35 69 σ32 60 σ53 51 σ30 32 σ18 Anterior 6th Rib Serratus 20 σ20 40 σ22 106 σ56 50 σ46 34 σ7 41 σ24 Anterior 4th Rib Rhomboids 7 σ8 35 σ21 41 σ26 71 σ35 45 σ28 14 σ20 Levator 0 σ5 35 σ14 72 σ54 70 σ29 33 σ10 14 σ13 Scapula Anterior 15 σ12 40 σ20 28 σ30 27 σ19 47 σ34 21 σ16 Deltoid Middle 9 σ8 44 σ19 12 σ17 36 σ22 59 σ19 16 σ13 Deltoid Posterior 6 σ9 42 σ26 28 σ27 68 σ66 60 σ28 13 σ11 Deltoid 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 7 σ9 26 σ22 62 σ19 56 σ31 41 σ23 25 σ18 Subscapularis Upper 7 σ8 37 σ26 99 σ55 115 σ82 60 σ36 16 σ15 Subscapularis Teres Minor 5 σ6 23 σ15 71 σ42 54 σ50 84 σ52 25 σ21 Latissimus 12 σ10 33 σ33 50 σ37 88 σ53 59 σ35 24 σ18 Dorsi Pectoralis 6 σ6 11 σ13 56 σ27 54 σ24 29 σ18 31 σ21 Major Biceps 4 σ6 22 σ14 26 σ20 20 σ16 44 σ32 16 σ14 Brachii Triceps 8 σ9 17 σ17 37 σ32 89 σ40 54 σ23 22 σ18 Brachii σ – Standard Deviation %MVIC – percent of maximum voluntary isometric contraction (DiGiovine, Jobe, Pink, & Perry, 1992)
Submarine Pitchers 12
Table 2
Joint Position of the Shoulder During Four Phases of Pitching GH Joint Positioning Arm Cocking Arm Arm Follow Start to Finish Acceleration Deceleration Through Rotation 53°ER- 178°ER- 105°ER-0°ER 0°ER- 178°ER 105°ER 30°ER Ab/adduction 90°AB- 100°AB- 95°AB- 100°AB- 100°AB 95°AB 100°AB 95°AD Horizontal 30°HAB- 14°HAD- 0°HAD- 30°AB- Ab/adduction 14°HAD 0°HAD 30°HAD 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 Submarine Pitchers 13
(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 Submarine Pitchers 14 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 Submarine Pitchers 15 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. Submarine Pitchers 16
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). Submarine Pitchers 17
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).
Submarine Pitchers 18
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 Submarine Pitchers 19 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 Submarine Pitchers 20 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- Submarine Pitchers 21 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 Submarine Pitchers 22
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 Force Application Positioning Infraspinatus Prone with humerus Fixation hand: Downward through abducted 90°, externally Cradling the humerus the forearm rotated 80°, and elbow near the elbow flexed 90° Pressure hand: Distal forearm
Middle Prone with the humerus Fixation hand: Downward toward Trapezius at the edge of the table Contralateral scapula the floor abducted to 90° and the Pressure hand: Distal elbow flexed 90°. The humerus scapula is retracted.
Posterior Prone with humerus Fixation hand: Obliquely downward Deltoid abducted 90°and slightly Stabilizing the and midway between externally rotated and scapula adduction and elbow flexed 90° Pressure hand: horizontal adduction Posterolateral surface of the humerus Lower Prone with humerus Fixation hand: On the Downward through Trapezius abducted 140° and opposite scapular the forearm externally rotated area to prevent trunk rotation Pressure hand: Distal 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 Submarine Pitchers 23 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.
Submarine Pitchers 24
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. Submarine Pitchers 25
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. Submarine Pitchers 26
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 Submarine Pitchers 27 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).
Table 4
Peak Muscle Activity During Each Exercise (Paired Samples Statistics) Mean N Std. Std. Error (%MVIC) Deviation Mean Pair 1 M Posterior Deltoid 1.0559 12 1.0245 .29574 MAX T Posterior Deltoid 1.1309 12 1.2972 .37447 MAX 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
A Pearson correlation coefficient was calculated for the relationship between participant’s of the maximum muscle activation achieved (normalized with % MVIC) for Submarine Pitchers 28 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 12 .913 .000 MAX 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
Submarine Pitchers 29
Table 6
Correlations in Peak Muscle Activity During Both Exercises T T Infraspinatus T Mid T Low Posterior MAX Trap Trap Deltoid MAX MAX MAX M Posterior Deltoid Pearson .913** .172 .184 .249 MAX Correlation Sig. (2- .000 .593 .568 .435 tailed) N 12 12 12 12 M Infraspinatus Pearson .784** .749** .329 .593* MAX Correlation Sig. (2- .003 .005 .297 .042 tailed) N 12 12 12 12 M Mid Trap MAX Pearson .306 .620* .765** .549 Correlation Sig. (2- .334 .031 .004 .064 tailed) N 12 12 12 12 M Low Trap MAX Pearson .390 .590* .732** .850** Correlation Sig. (2- .210 .043 .007 .000 tailed) 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 Submarine Pitchers 30
%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).
Submarine Pitchers 31
Table 7
Mean Difference in Peak Muscle Activity Between the Modified and Traditional Exercises (Paired Samples Test) Paired Differences t df Sig Mean Std. Std. 95% . Devia Error Confidence (2- tion Mean Interval of the tail Difference ed) Lowe Upp r er P M Post -.0749 .553 .160 -.426 .276 -.470 11 .64 ai Delt MAX 8 r - T Post 1 Delt MAX P M Infra .433 1.17 .339 -.313 1.18 1.28 11 .22 ai MAX - T 8 r Infra MAX 2 P M Mid .0291 .771 .223 -.461 .519 .131 11 .89 ai Trap MAX 8 r - T Mid 3 Trap MAX P M Low -.0881 .302 .0872 -.280 .104 -1.01 11 .33 ai Trap MAX 4 r - T Low 4 Trap MAX 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
Submarine Pitchers 32
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. Mea Std. Std. 95% Confidence (2- n Devi Error Interval of the tail ation Mea Difference ed) n Lower Upper P M Post -13.2 13.7 3.94 -21.8 -4.49 -3.34 11 .00 a Delt Y – 7 i T Post r Delt Y 1 P M Infra -5.78 14.0 4.04 -14.7 3.11 -1.43 11 .18 a Y – 0 i T Infra Y r 2 P M Mid -17.4 24.0 6.94 -32.7 -2.17 -2.51 11 .02 a Trap Y – 9 i T Mid r Trap Y 3 P M Low -14.1 18.0 5.20 -25.5 -2.66 -2.71 11 .02 a Trap Y – 0 i T Low r Trap 4 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
Submarine Pitchers 33
Table 9
Correlation of Glenohumeral Abduction Angle During Peak Muscle Activity T Posterior T T Mid T Low Deltoid Y Infraspinatus Trap Y Trap Y Y M Posterior Pearson -.259 .175 -.340 -.334 Deltoid Y Correlation Sig. (2- .415 .587 .280 .289 tailed) N 12 12 12 12 M Infraspinatus Pearson -.451 .206 .147 -.285 Y Correlation Sig. (2- .141 .521 .649 .370 tailed) N 12 12 12 12 M Mid Trap Y Pearson -.152 -.062 .018 .060 Correlation Sig. (2- .636 .849 .956 .853 tailed) N 12 12 12 12 M Low Trap Y Pearson -.236 .229 -.218 -.217 Correlation Sig. (2- .461 .474 .496 .498 tailed) 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 Submarine Pitchers 34 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 Submarine Pitchers 35 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 Submarine Pitchers 36 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 Submarine Pitchers 37 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 Submarine Pitchers 38 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. Submarine Pitchers 39
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