捕手三種投球動作之運動生物力學分析

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(1)National Taiwan Normal University College of Sports & Recreation Department of Athletic Performance - Master Thesis. Biomechanical Analysis of Three Different Catcher’s Throwing Motions. By: James Chen Advisor: Heng-Ju Lee, Ph.D.. 2015. . i .

(2) Biomechanical Analysis of Three Different Catcher’s Throwing Motions January 2015 Author: James Chen Advisor: Heng-Ju Lee Abstract The game of baseball brings together nine individuals to cohesively work together to reach one goal – to win. With a plethora of scenarios that could occur, one critical function of the catcher is to effectively manage base runners. The catcher is often depended on to minimize the opportunities of base runners stealing and advancing into scoring position. Most commonly seen base stealing occurs between first and second base. In contrast to other positions, the catcher makes throws of varying distances during the game, with the longest throws occurring between home and second base as the runner is attempting to steal. Often seen motions utilized by catchers throwing out potential base stealers are throws from the knees, the traditional throw down, and the pitch out. In order to successfully impede stolen bases, the catcher must receive the pitched ball, transfer the ball to the throwing hand, and deliver an accurate throw thirty-eight meters away in less than two seconds. The purpose of this study was to explore and understand inherent differences between the three throwing motions’ joint kinematics when throwing to second base and the effect on performance. 3D-motion analysis cameras captured and yielded kinematic data for the test participants. The pitch out throws generated the fastest ball velocities and total time for the ball to reach second, further substantiating the assumption that the pitch out is in fact the quickest motion to second base. Interpreting and fathoming the results of this study imparts knowledge for plausible training methods to increase performance while possibly reducing the risk of injury. Keywords: joint kinematics, overhead athletes, baseball, performance. . ii .

(3) Acknowledgement. I am extremely privileged to be under the tutelage of Professor Heng-Ju Lee, and would like to extend my sincerest appreciation. Dr, Lee has provided extraordinary support while I pursued my degree in Taiwan. I am extremely grateful for the opportunity to have done research in the shared biomechanics laboratory of the Department of Athletic Performance and Department of Physical Education at National Taiwan Normal University. I would not only like to thank Professor Heng-Ju Lee for his counsel in completing this master’s thesis, but am extremely fortunate to have found a mentor that has opened new possibilities and paved the way for a hopefully successful future in the field of physical therapy, strength and conditioning training, and sports medicine. Furthermore, I would like to thank my committee members, Dr. Tzyy-Yuang Shiang and Dr. Chiang Liu for their patience and insightful advice. I would like to thank my colleagues in the sports biomechanics laboratory as well as the athletic training facility for all the assistance and guidance they have provided during my stay. To my family and friends: thank you for your patience and encouragement throughout this process, without you all, this would not have been possible.. . iii .

(4) Table of Contents Chapter 1. Introduction ........................................................................................................................... 1 Statement of the Problem ...................................................................................................................... 3 Research Hypothesis ............................................................................................................................. 3 Delimitations ......................................................................................................................................... 3 Limitations ............................................................................................................................................ 3 Definition of Terms ............................................................................................................................... 4. 2. Review of Literature.............................................................................................................. 6 Baseball Objective ................................................................................................................................ 6 Offensive Strategy................................................................................................................................. 6 Defensive Strategy ................................................................................................................................ 7 Catcher’s Throwing Motion ............................................................................................................. 8 Ball Velocity ................................................................................................................................... 10 Injury ................................................................................................................................................... 11. 3. Methodology ......................................................................................................................... 14 Research Design .................................................................................................................................. 14 Participants and Selection Criteria ...................................................................................................... 14 Outcome Measurements and Instrumentation..................................................................................... 15 Anthropometric Data Collection ......................................................................................................... 15 Equipment ........................................................................................................................................... 15 Research Protocol ............................................................................................................................... 16 Throwing from the Knees ............................................................................................................... 19 The Traditional Throw Down ......................................................................................................... 19 Pitch Out ......................................................................................................................................... 20 Research Protocol Flow Chart ............................................................................................................ 21 Data Processing ................................................................................................................................... 22. 4. Results ................................................................................................................................... 25 5. Discussion ............................................................................................................................. 34 Joint Kinematics .................................................................................................................................. 35 The Kinetic Chain and Stretch Shortening Cycle ............................................................................... 38 Application .......................................................................................................................................... 40. 6. Conclusion ............................................................................................................................ 45 References ................................................................................................................................ 48 Appendix I ................................................................................................................................ 56. . . . iv .

(5) List of Figures Figure 2-1. Phases of the throwing motion ……………………………………………….….…..9 3-1. Experimental set-up ………………………………………………………………...16 3-2. Reflective marker model …………………………………………………………...18 3-3. Throwing from the knees’ throwing motion …………………………….…………19 3-4. Traditional throw down throwing motion …………………………….……………20 3-5. Pitch out throwing motion ………………….………………………………………20 3-6. Throwing phases …………………………………………..………………..............23 3-7. Maximum shoulder external rotation ………………………………………………24 4-1. Ball velocity for the three throwing motions ……………………………………….25 4-2. Total time to second base …………………….…………………………………….27 4-3. Trunk angular velocity for the three throwing motions …………………………….29 4-4. Relationship between TD kinematic parameters and ball velocity ………………...31 4-5. Relationship between PO kinematic parameters and ball velocity ………………...31. . v .

(6) List of Tables Table 3.1. Reflective marker placement locations ……………………………………………..17 3-2. Joint kinematics analysis parameters …………………………………..…………...24 3.1. Comparison of joint kinematics between throwing positions ………………………28 3.1. Correlation between joint kinematics and throwing motions ……………………....30. . vi .

(7) Chapter 1 – Introduction Baseball, America’s national pastime, is one of the more popular team sports played and watched in the United States (Porterfield, 2007). Nine players take the field to defend against the opposing team’s offense. The outfielders defend against the fly balls and ground balls that manage to get past the infield. The shortstop, first, second, third basemen, and pitcher compose of the infielders that defensively protect the infield area. After receiving the signal from the catcher, the pitcher prepares to pitch to outsmart the batter (Freeman, 2006). The catcher is often viewed as the defensive leader of the team due to the constant involvement with every pitch and the only player on the field with the ability to see the entire field of play (Freeman, 2006). One mistake by the catcher, however, could possibly mean the difference in the outcome of the ball game. Opposing the defense, the offense consisting of both batters and base runners, strive to create as many opportunities as possible to score runs in order to win the ballgame. With runners on base, the possibility of scoring greatly multiplies, particularly if runners, via base hits and/or stealing bases, reach second or third base. Stealing bases is one of the strategies employed by offenses to advance runners into scoring position (Freeman, 2006).. Although suppressing. runners from stealing is two fold due to the involvement of both pitcher and catcher, the catcher plays a more pronounced role in effectively catching a base stealer. How quickly a catcher is able to release the ball, accurately throw, while throwing with a fast velocity, determines the successfulness of the catcher (Freeman, 2006). The baseball catcher throws more frequently than any other player on the field and is often graded heavily on their throwing ability by professional scouts (Walter, 2002). A plethora of studies analyze baseball pitchers’ throwing mechanics, however, very limited research centers on the catcher. It is with this understanding that the throwing motion of the baseball catcher also be studied.. . 1 .

(8) Background Defensively, pitchers and catchers collectively manage the defensive rhythm of the game in order to thwart runners from attempting to steal bases to advance into scoring position. The catcher’s involvement in every pitch can potentially influence game outcomes, thus making this position one of the most rigorous in the game of baseball (Plummer & Oliver, 2013). Runners are far more likely to score from second base than from first base (Sheehan, 2004). Therefore, one of the many responsibilities of the catcher is to impede runners from advancing into scoring position by means of a stolen base (Bail, 2005). A catcher must receive the pitched ball in a squatted position and throw the ball to second base in approximately 2 seconds in order to catch a base stealer (Fortenbaugh, Fleisig, & Bolt, 2010; Scala, 2009; Walter, 2002). The distance between home plate and third base measures 27.4 meters, identical to the distance between home plate and first. However, the distance increases to 38.8 meters from home plate to second base, consequently resulting in base stealing occurring more commonly between first and second base. When the catcher notices a runner attempting to steal second, the catcher must catch the ball thrown by the pitcher, transfer the ball smoothly and “cleanly” into the throwing hand, while concurrently begin the throwing motion to deliver the ball to second base (Fortenbaugh, Fleisig, & Bolt, 2010; Plummer & Oliver, 2013). Three commonly seen throwing motions catchers used are throws from the knee, the traditional throw down, and the pitch out. It is assumed amongst the baseball community that the pitch-out would be the quickest and most ideal method to throwout a base runner attempting to steal second base (Fortenbaugh, Fleisig, & Bolt, 2010). However, if the pitch-out is executed, a ball is called and an unfavorable count results. Conceivably, studying the motions of the three throws can provide coaches a clearer picture as to which motion to utilize to increase the chances of successfully preventing stolen bases.. . 2 .

(9) Purpose The purpose of this study was to investigate and understand the joint kinematics of the three throwing motions: throwing from the knees, traditional throw down, and pitch out, when throwing to second base. Furthermore, comprehending throwing motion kinematics will provide insight to the effects on performance and potential improvements made to enhance performance. Hypothesis 1. The three throwing motions would have significantly different throwing kinematics. 2. The performance results (ball velocity, pop time, and time to second base) would show significant differences between the three throwing motions. Limitations of the Study Delimitations The study was delimited to the following: 1. Participants were active, healthy, professional baseball players in Taiwan’s professional baseball league. 2. Specific instructions were given to the participants in order to standardize testing protocols. 3. The throwing order protocols were randomly assigned to avoid an ordering effect. Limitations The study was limited by the following:. . 3 .

(10) 1. An indoor, controlled testing setting without environmental influences such as wind, sunlight, dirt ground, etc. 2. Participants may vary in their respective warm-up techniques and routines. 3. Participants may vary in their respective throwing mechanics 4. Variations in participant’s catcher’s mitt. 5. Variation in participants shin guards and foot wear. 6. Absence of catcher’s facemask and chest protection gear. 7. Variation in velocity and location of the pitches delivered to the catcher. 8. The absence of a runner stealing second base. Definition of Terms Catcher – one of nine players on the field. Crouches behind the batter’s box and in front of the home plate umpire. Receives the thrown ball from the pitcher. Pitcher – one of nine players on the field; throws from the pitcher’s mound to the catcher to initiate each play. Base-stealing / Stolen bases – a strategy utilized to advance base runners into scoring position Scoring position – a runner is on second or third base Throwing from the knees – a throwing method to deliver the ball to second base by throwing the ball from a kneeling position. Traditional throw down – a throwing method to deliver the ball to second base. The catcher receives the ball from the pitcher, transfers the ball to the throwing hand, hops and turns the body perpendicular to second base, and continues to step and throw the ball to second base.. . 4 .

(11) Pitch out – a throwing method to deliver the ball to second base. Prior to receiving the ball from the pitcher, the catcher takes a side step to the left hand’s batter box, catches the ball from the pitcher while stepping forward, transfers the ball to the throwing hand, and continues to step and throw the ball to second base. Ball velocity – the velocity (meters per second) of the ball measured from the moment the ball is released from the catcher’s hand. Pop time – the time duration between: the moment the ball is caught to the ball leaving the catcher’s hand. Time to second base – the time duration between: the moment the ball enters the catcher’s glove, leaves the catcher’s hand, and travels 38.795 meters to second base. Stride Length – the distance between the heel of the front foot and the heel of the rear foot. Kinematics – to analyze the human body in the action of throwing a baseball to second base via three throwing motions. Angular velocities and joint angles parameters are measured, however force parameters are excluded.. . 5 .

(12) Chapter 2 – Review of Literature Prior to comprehending the correlations between a catcher’s throwing motions and performance outcomes, it is necessary to discuss the reasoning for the throws made and elaborate on the elements that come into play when a ball is thrown. Baseball Objectives and Measurements Baseball is a competitive game between two teams whose main objective is to win by outscoring the opponent in total runs (Major League Baseball - Professional Baseball Playing Rules Committee). A regulation baseball diamond measures 90 feet (27.432 meters) from home plate to third base, 90 feet (27.432 meters) from home plate to first base, and 127 feet 3 3/8 inches (38.795 meters) from home plate to second base (Major League Baseball - Professional Baseball Playing Rules Committee). Baseball – Offense The offensive game in baseball consists of batters and base runners. Batters face pitchers with the goal of getting on base or simply scoring by hitting a homerun. There are four main methods of reaching the base paths: being walked (BB), hit-by-pitch (HBP), reach on error (ROE), bunting, or hitting the ball. Once base runners are present, the main objective is to increase the possibilities of reaching home and scoring. The chances of scoring are increased once runners advance into scoring position i.e. second or third base. Base runners are able to advance on the base paths when hitters behind them reach base on balls (BB), hit-by-pitch, recording a base hit, or sacrifice bunt or fly. Base runners themselves can also advance when the pitcher throws a wild pitch, a catcher has a pass ball, or the runner can steal a base. Base stealing in particular is often considered a vital aspect of offence in the game of baseball (Loughin & . 6 .

(13) Bargen, 2007). Having base runners allow the offense to steal runs and put pressure on the opposition (Scala, 2009). Base stealing is a commonly used strategy in baseball to advance runners into scoring position (Freeman, 2006). Baseball – Defense In order to defend against the offense, nine players take the field. Outfielders defend against any hit ball that gets past the infield. Infielders field any balls hit within their range or is in the vicinity of the bases when balls are thrown to the base to record an out. The battery consists of the pitcher and the catcher (National Alliance for Youth Sports & Bach, 2007). The pitcher begins each play by throwing the ball towards home plate with the objective of getting the batter out (National Alliance for Youth Sports & Bach, 2007). The catcher, commonly referred to the general of the baseball game, is able to see the entire field of play and is consistently involved in every play (Scala, 2009). It is the responsibility of the pitcher and catcher to keep runners close to the base, and a primary responsibility of the catcher to thwart would be base stealers by catching the pitched ball and quickly throw the ball towards the base being stolen in order to throw out the base runner (National Alliance for Youth Sports & Bach, 2007; Scala, 2009; Loughin & Bargen, 2007, LA84 Foundation, 2007). Catchers need to be quick and make fast and accurate throws to catch the base runner (Scala, 2009; Loughin & Bargen, 2007).. . 7 .

(14) Catcher throwing motions Catchers are required to make the most throws during the course of a baseball game, with their throwing ability being highly valued by professional scouts (Fortenbaugh & Fleisig & Bolt, 2010). In order to throw out base runners attempting to steal second base, the catcher must accurately throw the ball roughly 40 meters in at least 2.0 seconds (Fortenbaugh & Fleisig, & Bolt, 2010; Scala, 2009). The catcher begins each pitch in a deep, squatted position (Fortenbaugh & Fleisig & Bolt, 2010). The catcher must then receive the pitched ball, rise from the squatted position, move the glove closer to the throwing hand, and smoothly and quickly transfer the ball from the glove to the throwing hand (Scala, 2009; National Alliance for Youth Sports & Bach, 2007; Plummer & Oliver, 2013). The catcher then rotates the hips and shoulder toward second base and begins the throwing motion (National Alliance for Youth Sports & Bach, 2007). In the ideal condition, a pitch out is used. In this scenario, the catcher catches the pitched ball at a nearly erect position’s chest height in the unimpeded batter’s box. This allows for an unobstructed throw to second base (Fortenbaugh, Fleisig, & Bolt, 2010). Significant amount of research regarding throwing kinematics and kinetics has been conducted on pitchers (Urbin, Fleisig, Abebe, & Andrews, 2013; Fleisig, Bolt, Fortenbaugh, Wilk, & Andrews, 2011; Dun, Kingsley, Fleisig, Loftice, & Andrews, 2008; Hirashima, Yamane, Nakamura, & Ohtsuki, 2008; Keeley, Oliver, & Dougherty, 2012; Hirashima, Kadota, Sakurai, Kudo, & Ohtsuki, 2010). Similar to pitching, catchers too must rotate the trunk to face the intended target. The core muscles can be optimally sequenced in the kinetic chain with proper timing between the pelvis and trunk rotation (Urbin, Fleisig, Abebe, & Andrews, 2013). Following the rotation of the trunk, the shoulder must externally rotate while flexing the elbow. After reaching maximum shoulder external rotation, the shoulder must internally rotate and the . 8 .

(15) elbow extended with great acceleration in order to throw the ball (Plummer & Oliver, 2013). The phases of the throwing motion described previously can be can be seen in figure 2-1. Fortenbaugh, Fleisig, and Bolt observed that the catcher’s throwing mechanics differ from other players in that shorter strides are taken as well as very little pelvis and trunk separation that is more commonly seen in pitching (Fortenbaugh, Fleisig, & Bolt, 2010). When the throwing distance was increased past the distance of the pitcher’s mound, it was observed that players relied more on greater pelvis angular velocity, trunk angular velocity, elbow flexion, and elbow extension velocity (Fleisig, Bolt, Fortenbaugh, Wilk, & Andrews, 2011). The greater distance also resulted in higher elbow and shoulder torques, as well as increased maximum shoulder external rotation angles (Fleisig, Bolt, Fortenbaugh, Wilk, & Andrews, 2011). The dissimilar throwing mechanics in comparison to pitching results in lower ball velocities by the catcher, however demonstrate virtually homogenous stress on the shoulder and elbow joints when analyzed with pitching and long-toss; the change in motion is perhaps due to the catcher’s need to quickly throw the ball to the target (Fortenbaugh, Fleisig, & Bolt, 2010).. Figure 2-1. Phases of the throwing motion.. . 9 .

(16) Ball Velocity Throwing velocity is imperative for pitchers and position players in the game of baseball (Escamilla, Fleisig, Yamashiro, Mikla, Dunning, Paulos, & Andrews, 2010; Escamilla, Ionno, DeMahy, Fleisig, Wilk, Yamashiro, Mikla, Paulos, & Andrews, 2012). The ability to throw the ball at a higher velocity could be improved via throwing mechanics or instituting strength and conditioning programs (Escamilla, Fleisig, Yamashiro, Mikla, Dunning, Paulos, & Andrews, 2010). Additionally, efficient throwing mechanics could possibly maximize the velocity of the thrown ball (Fortenbaugh & Fleisig, 2009). The upper and lower body influences pitching kinematics that ultimately affect ball velocity (Fortenbaugh, Fleisig, & Andrews, 2009). Throwers that are able to efficiently use the kinetic chain are capable of maximizing the ball’s velocity (Fortenbaugh & Fleisig, 2009). When timing between the peak angular velocities of the pelvis and trunk increases, ball velocity was found to decrease (Urbin, Fleisig, Abebe, & Andrews, 2013). It was found that balls thrown at a higher velocity have higher kinetic values about the elbow and shoulder (Fortenbaugh, Fleisig, & Andrews, 2009). Additionally, pitchers throwing at a higher ball velocity demonstrated greater maximum shoulder external rotation and forward trunk tilt angles at ball release (Fleisig, Bolt, Fortenbaugh, Wilk, & Andrews, 2011). Hirashima et al. (2008) found that ball velocity dependent torques about the shoulder, elbow, and wrist were created by the angular velocity of the forearm that originated from trunk and shoulder joint torques in the earlier phases of the throwing motion. Catchers demonstrate throwing motions similar to pitchers, however with a shortened motion (Plummer & Oliver, 2013). However, the ball velocity for pitchers is still greater than those of catchers (Plummer & Oliver, 2014). Ball velocity was not compromised due to pitchers changing delivery styles (Keeley, Oliver, & Dougherty, 2012). After comparison of two different age group of catchers, grouped 9-. . 10 .

(17) 14 and 15-23, Plummer and Oliver (2013) discovered that ball velocity would be increased as the catcher matures and have further muscular gains in strength. It was found that utilizing different throwing distances to train for faster ball velocities was not necessarily effective (Fleisig, Bolt, Fortenbaugh, Wilk, & Andrews, 2011). Injury Due to the vast amount of research on pitcher’s and their mechanics and pathomechanics, a substantial amount of research is related potential injury risks and practices that could limit the chance of injury. Overhead throwing athletes, such as baseball players, have an increased risk for overuse injuries with the shoulder and elbow commonly sustaining injury (Han, Kim, Lim, Park, & Oh, 2009). The high speeds of the throwing motion have extreme repercussions to the dynamic stabilizing structures in the upper body, raising the risk of injury (Meister, 2000). A catcher’s ability to optimally sequence the throwing motion could potentially decrease the forces on the elbow, shoulder, and trunk, thus lowering the risk for injury that could occur due to improper motions (Plummer & Oliver, 2013). In addition, to minimize the strain on the throwing arm and reduce risk of injury is through an efficient total body mechanical sequence (Fortenbaugh & Fleisig, 2009). In order to achieve this mechanical efficiency, Fortenbaugh and Fleisig (2009) suggested stronger legs and core muscles to sustain the larger loads rather than rely on the weaker and smaller arm muscles. By efficiently utilizing the kinetic chain during throwing, pitchers can minimize upper extremity kinetic values to reduce injury risk (Fortenbaugh & Fleisig, 2009). Kibler (1998) was able to conclude that when a 20% decrease in the transfer of energy from trunk, hip and proximal segments to the throwing arm would need an 80% increase in mass or at least a 34% more rotational velocity in the shoulder joint. Plummer and Oliver (2013) hypothesized that if wrong throwing mechanics are utilized then shoulder and . 11 .

(18) elbow moments will increase. Preventing pathomechanics and providing appropriate rehabilitation training programs could potentially be achieved with the knowledge of moments increasing about the shoulder and elbow during the throwing motion. (Plummer & Oliver, 2013). Plummer and Oliver (2013) suggest those in immediate contact with catchers and their training should incorporate strength programs that target the rotator cuff in order to increase musculature and decrease any risk of epiphyseal injury. Ulnar collateral ligament (UCL) injuries as well as superior labral tear from anterior to posterior (SLAP) in baseball players are becoming increasingly common, however exact reported findings could not be confirmed (Han, Kim, Lim, Park, & Oh, 2009). Consistent and repetitive high force throws correlates with high varus torque in the elbow, thus could result in gradual attenuation of the UCL (Fleisig, Bolt, Fortenbaugh, Wilk, & Andrews, 2011). Following recovery and rehabilitation from UCL and SLAP surgery, players should avoid maximum distance throws until the later stages of rehabilitation due to the increased varus torque and elbow extension velocity (Fleisig, Bolt, Fortenbaugh, Wilk, & Andrews, 2011). Additionally, rotator cuff injury was also fairly commonly seen in baseball players (Mazoué & Andrews, 2006). The overhead thrower usually would complain of discomfort in the neck or shoulder and observes a loss of throwing velocity after sustaining shoulder injury (Seroyer, Nho, Bach, BushJoseph, Nicholson, & Romeo, 2009). Comparing players of taller statures and heavier builds, Han et al. (2009) observed that these players were more prone to UCL injury and SLAP lesions. Much like pitchers, catchers are commonly hampered by shoulder and elbow injuries, in addition to wrist injuries (Li, Zhou, Williams, Steele, Nguyen, Jäger, & Coleman, 2013). Efficient throwing mechanics resulted in lower shoulder torques and lower elbow valgus loads (Kibler & Thomas, 2012). Pitchers who required operative treatment for rotator cuff tears did not return to. . 12 .

(19) pre-injury performances levels (Namdari, Baldwin, Ahn, Huffman, & Sennett, 2011). Mazoué & Andrews (2006) also found that professional pitchers who underwent operative treatment for rotator cuff tears had an extremely difficult chance to return to a competitive level of pitching. Conclusion Based on the aforementioned literature, past research focused predominantly on the pitcher’s throwing mechanics. The primary concern of many researchers studying baseball throwing motions focused on the sequencing of the body and kinetic chain, how throwing performance was affected by the sequencing of events, and if any injury implications exist. Limited research pertains to the catcher, another imperative position in baseball that consistently throws more than any other player on the field. Therefore, by evaluating catcher throwing motions, it would be possible to further assess the implications the catcher’s throwing mechanics has on performance, injury, and training.. . 13 .

(20) Chapter 3 – Methodology Research Design This was an experimental design that was randomized and within-subject study. The research investigates the kinematic differences and performance results between the throwing motions. The independent variables were the three throwing motions: throwing from the knees (K), the traditional throw down (TD), and the pitch-out (PO). The dependent variables will include joint angles (shoulder: abduction, extension, internal rotation, and external rotation; elbow: flexion and extension; trunk: forward and lateral tilt), joint angular velocity (shoulder internal rotation, elbow extension, and trunk rotation), ball velocity, pop time, time to second base, and stride length for TD and PO. The study used a counterbalance design to account for ordering effects in which the order of the throwing conditions were randomly assigned to each subject. Participants and Selection Criteria Eleven healthy, male, right-handed, professional catchers were recruited from Taiwan’s professional baseball league to partake in the study. The data collected from the study were used in the statistical analysis. Participants were excluded if they have sustained an injury to the shoulder, elbow, and/or upper torso in the six months prior to recruitment. The participants partaking in the study completed an Informed Consent form prior to testing procedures. Upon completion of the Informed Consent form, the test participants completed baseball history questionnaires to confirm that an injury to the shoulder, elbow, and/or torso did not occur in the past six months.. . 14 .

(21) Outcome Measurements and Instrumentation Each participant completed the testing in one session, which lasted approximately an hour and a half. All testing sessions were performed in the National Taiwan Normal University (NTNU) Athletics building’s first floor indoor track. The testing session consisted of a period of instruction, walk-thru, demonstration, and practice of the throwing motions for familiarization. All participants will have an assigned subject identification number, which was used to identify the data recorded on pre-made data collection documentation and Vicon’s motion capture system. Anthropometric Data Collection Anthropometric data was collected for each participant, with self-reported figures for height and weight. A Vernier scale was used to measure the: shoulder radius and offset, elbow width, wrist width, hand thickness and width, knee width, ankle width, and anterior superior iliac spine (ASIS) width. Furthermore, a tape measure was used to measure the length of the leg. Anthropometric data was collected for both left and right extremities. Equipment -. Vicon T-Series Motion Capture System (T-20s Vicon Motion Systems Ltd., Oxford, UK) infrared cameras recorded at 250 Hz to capture and record the reflective markers that were affixed to the joints on the test participants. The changes in the position of the reflective markers with respect to the lab coordinate system were recorded by the Vicon Nexus 1.8.1 software system in order to conduct kinematic analysis following the testing sessions.. -. Visual3D (C-motion, Inc., Maryland, USA) was used to calculate kinematic data recorded by the Vicon system.. . 15 .

(22) -. Baseball – brand new, regulation size ball (5 oz.). -. Baseball catcher’s mitt and shin guards. -. Vernier scale, tape measurer. -. Double sided tape, kinesiology tape, other supplies (scissors). Research protocol Data collection occurred inside the NTNU Athletics building’s indoor track. Prior to the arrival of the test participants, the order of throw motions was randomly assigned for each participant. The participants were scheduled for two-hour sessions for data collection with the researcher and were blinded to their testing order assignment until arrival to the facility. All participants had the purpose of the study explained to them and completed a baseball and medical history questionnaire upon reporting to the testing session. Following the completion of the questionnaire, an informed consent was read and signed before proceeding with the study. Via a walkthrough, the researcher informed the participant of the testing confines and demonstrated the three throwing motions to be tested. The eight cameras created a capture zone surrounding home plate, both batter’s boxes, and the catcher’s area. The distance from home plate to second base measured 38.8 meters with a pitcher’s area ten meters away from home. Figure 3-1. Experimental setup. . 16 .

(23) plate. At the conclusion of the instructional period, reflective markers were affixed to the C7 and T10 vertebrae, acromion, lateral and medial epicondyle of the elbow, distal ulna and radius bony landmarks, dorsum of hand at head of second metacarpal, left and right ASIS, and left and right PSIS. Additional markers for tracking purposes were affixed to the right scapula, upper arms, and forearms. A headband with four reflective markers was secured on the participant’s head. Lower extremity markers were fixed to the thighs, shin guards, and shoes of the participants. Kinesiology tape secured the reflective markers onto the test participant. The model of reflective markers can be seen below. Table 3.1 Reflective Marker Placement Locations Left/Right Front Head Left/Right Back Head C-7. Left/Right Lateral Epicondyle of Humerus Left/Right Medial Epicondyle of Humerus Left Forearm. T-10. Right Forearm 1. Right Scapula. Right Forearm 2. Left/Right Acromion Left Upper Arm Right Upper Arm 1 Right Upper Arm 2 Right Upper Arm 3. Left/Right ASIS Left/Right PSIS Left/Right Thigh Left/Right Lateral Epicondyle of Femur Left/Right Medial Epicondyle of Femur. Right Forearm 3. Left/Right Tibia. Left/Right Radial Styloid Process. Left/Right Lateral Malleolus. Left/Right Ulna Styloid Process. Left/Right Medial Malleolus. Left/Right 3rd Metacarpal. Left/Right Heel. Right 2nd phalanx. Left/Right 3rd Metatarsal. Right 3rd phalanx. . 17 .

(24) Figure 3-2. Reflective marker model.. After the placement of all reflective markers, the participants were allowed to warm up using their preferred routine. Once warm up was completed, the participants were asked to perform three successful trials for each throwing motion (throws from the knee, traditional throw down, and the pitch out). Prior to formal testing, the participants were given practice trials with regulation baseballs affixed with reflective tape to become familiar with the motions, ball, and pitcher throwing the ball. The test participants were reminded to simulate in-game scenarios when performing each trial i.e. quickly transfer and throw the ball as fast as possible to second base. When the researcher began the start of each trial, the pitcher proceeded to deliver the ball to the catcher. The ball thrown to the catcher would have to be in a catchable range for the catcher. A trial was deemed unsuccessful if the delivery of the ball to the catcher was too low (below the knees of the catcher) or too high (above the head of the catcher). While a trial was deemed successful if the participant catches the ball, smoothly transferred the ball to the throwing hand, takes one step, and throws the ball to second base within a catchable range. If the . 18 .

(25) test participant took any additional steps the trial was deemed unsuccessful. Furthermore, if the ball thrown to second base was out of catchable range at second base, the trial was deemed unsuccessful. The test participant would then be asked to redo the trial. Resting periods of two minutes were given in between each trial and five minutes between each throwing motions in order to avoid fatigue. Throwing from the knees In order to perform this throwing motion successfully, the test participant began in a crouched/squatted position – the ready position. The subject awaited the delivery of the ball from the pitcher during this time. Once the ball was pitched, the catcher first must catch the ball and proceed to transfer the ball to the throwing hand. During the transfer, the catcher began to kneel on both knees to prepare to throw the ball to second base.. Figure 3-3. Throwing from the knees’ throwing motion. The traditional throw down The traditional throw down required the test participant to begin in the ready position. Once the ball was delivered to the catcher, the catcher received the ball and began to transfer the ball to the throwing hand. During this transfer phase, the catcher simultaneously hops up and turns their body perpendicular to second base with their left foot pointing towards second base.. . 19 .

(26) Once the body was turned, the catcher proceeded to take only one step with the left foot and throws the ball to the target.. . . Figure 3-4. The traditional throw down’s throwing motion. Pitch out Performing the pitch out requires the catcher to begin in the ready position. However, unlike the previous two motions, the pitch out would have the catcher take a few steps towards the left-hand batter’s box to catch the ball from the pitcher. Once the ball was caught, it was transferred to the throwing hand; the catcher takes one step and throws to the target.. . . . . . . . . . Figure 3-5. The pitch out’s throwing motion.. . 20 .

(27) Research protocol flow chart Report to the athletics building's indoor track . Describe purpose of study . Complete baseball & medical history questionnaire . Read and sign the informed consent form . AfHix reHlective markers . Instruction, walk-‐thru, and demonstration of throwing motions . Allow subject to warm up . Familiarization of throwing motions Begin testing (random order assigned) . Throws from the knee (3 successful trials) . . Throws from the traditional throw down (3 successful trials) . Throws from the pitch out (3 successful trials) . 21 .

(28) Data processing Statistical Package for the Social Sciences (SPSS for Windows, 20.0, IBM, New York, USA) was used to perform the statistical analysis for this study. Descriptive statistics (mean ± SD) for the test participants’ age, height, weight, and baseball experience was calculated. A oneway repeated measures analysis of variance (ANOVA) test was used to assess the differences between the three motion’s joint kinematics and performance results, α = .05. Regression analysis provided the means to determine the relationships between joint kinematic measurements and performance results. Kinematic analysis was performed with C-Motion’s Visual3D software. Reflective markers affixed to the bony landmarks allowed for calculations of the shoulder and elbow joint angles as well as the trunk rotation angles relative to the local coordinate system: x-axis is in the direction towards second base, y-axis is to the left and right of home plate, while the z-axis is in the vertical direction above home plate. The rotation angle sequence (Euler Angles) to be used for shoulder calculations was Z-Y-Z with the x-direction portraying the flexion and extension, ydirection representing abduction and adduction, and the z-direction characterizing internal and external rotations. Elbow rotation sequences utilized Cardan angles of X-Y-Z to calculate the flexion and extension motions that occurred in the x-direction. Cardan angles (Y-X-Z) were also used to calculate the forward tilt (y-direction) and lateral tilt angles (x-direction) of the trunk. Furthermore, angular velocities for shoulder internal rotation, elbow extension, and trunk rotation were calculated with the Visual3D software. Performance factors were calculated with the Vicon Nexus 1.8.1 software, tracking the reflective markers of the subject’s foot and the ball relative to the local coordinate system.. . 22 .

(29) The throwing motion of a catcher throwing to second base was defined into five phases: 1) Ready position, 2) Catching and transfer, 3) Stride and arm cock, 4) Arm acceleration, and 5) Ball release phases. Joint kinematic and performance analysis initiated the moment the ball entered the glove of the catcher in the second phase. In this phase, pop time performance data recording began. As the catcher continued through the throwing motion into the stride and arm cock, kinematic data for maximum shoulder external rotation angle, shoulder extension, shoulder abduction, elbow flexion, and trunk lateral tilt angles were analyzed. As the arm progressed through the acceleration phase, maximum trunk extension angles, shoulder internal rotation, elbow extension, and trunk rotation velocities examined. The last phase investigated the shoulder internal rotation, elbow extension, and trunk forward tilting angles when the ball was released. The instant the baseball left the fingers of the catcher’s throwing hand, the pop time’s time recording ceased. Ball velocity was calculated as soon as the ball was released. The total elapsed time for the throw to second base was calculated with the addition of pop time and the time required for the ball to travel 38.795 meters to second base.. Figure 3-6. Throwing phases.. . 23 .

(30) Table 3.2. Joint Kinematics Analysis Parameters Shoulder Max Extension. Elbow Extension Velocity. Shoulder Max Abduction. Trunk Forward Tilt. Shoulder Max External Rotation. Trunk Lateral Tilt [Left]. Shoulder Max Internal Rotation. Trunk Extension. Elbow Max Flexion. Trunk Rotation Velocity. Elbow Max Extension. Shoulder Internal Rotation Velocity. Figure 3-7. Maximum shoulder external rotation.. . 24 .

(31) Chapter 4 – Results Average ball velocities differed between all three motions. The traditional throw down recorded an average ± standard deviation velocity of 29.9 ± 2.8 meters per second (m/s), ranking second fastest, just behind the pitch out’s 31.4 ± 2.6 m/s. Throwing from a kneeling position produced the slowest ball velocity of the three motions, 27.7 ± 2.2 m/s.. *. 40. Velocity (m/s). 30. 20. 10. 0 Throwing from the knees. Traditional throw down. Pitch out. Figure 4-1. Ball velocity of the three throwing positions.. In the study, pop time was defined as the moment the ball was caught to the ball being leaving the catcher’s hand. Knowing the ball velocity and distance to second base, the time needed for the ball to travel to second base was calculated. Together, the total time to second base was determined. Observable differences were displayed between the traditional thrown. . 25 .

(32) down and throwing from the knee positions when pop time was analyzed. The traditional throw down recorded the slowest pop time of 0.79 ± 0.1 seconds, but with a time of 2.10 ± 0.1 seconds was the second fastest for the total time to second base. The pitch out clocked the second quickest pop time, 0.77 ± 0.1 seconds, and produced the quickest overall time to second base of 2.02 ± 0.2 seconds. Throwing from a kneeling position generated the fastest pop time out of the three positions, however, it recorded the slowest total time to second base. The total time to second base for the pitch out demonstrated significant differences when analyzed with the two other positions. Nonetheless, the pop times of the traditional throw down and pitch out did not exhibit any differences. Although pop times for the traditional throw down and pitch out were slower than that of throws from the knees, with a significantly faster ball velocity allowed the two throwing motions to reduce the overall time to second base.. . 26 .

(33) Total time to second base (s) . 2.5 . 2 . 1.5 Pop time 1 . Ball velocity . 0.5 . 0 Throwing from the knees . Traditional throw down . Pitch out . Figure 4-2. The total time to second base from the time the ball is caught to leaving the catcher’s hand (pop time) and the time needed for the ball to travel 38.795 meters to second base (ball velocity).. The stride lengths of the traditional throw down and pitch out measured 1.22 ± 0.1 meters and 1.2 ± 0.1 meters, respectively. The traditional throw down’s stride length was 70.1% ± 2.0% of the catcher’s height. The stride length for the pitch out in relation to the catcher’s height was 68.9% ± 2.0%. As the catcher progressed to the stride and arm cock phase of the throwing motion, the traditional throw down exhibited the highest average shoulder external rotation angle of 138.4 ± 12.8 degrees. The pitch out and throwing from the knees exhibited angles of 137.5 ± 11.9 and 135.1 ± 12.9 degrees, respectively. Shoulder extension for the traditional throw down and pitch out had observable differences, with the former having a higher shoulder extension of 21.7 ± 10.7 degrees and the latter of 20.2 ± 10.9 degrees. Differences were additionally observed. . 27 .

(34) in the trunk lateral tilt to the left. Throwing via the traditional throw down demonstrated the most lateral trunk tilt. The pitch out recorded an average of 18.3 ± 5.2 degrees for trunk tilting to the left. Throwing the ball to second base from the kneeling position showed 11.5 ± 5.7 degrees of trunk lateral tilt.. Table 4.1 Comparison of Joint Kinematics Between Three Throwing Positions Traditional Throwing from throw down a the knees b Stride & Arm cock Shoulder External Rotation (°) Shoulder Extension (°) Shoulder Abduction (°) Elbow Flexion (°) Trunk Lateral Tilt [Left] (°) Arm Acceleration Trunk Extension (°) Shoulder Internal Rotation Velocity (°/s) Elbow Extension Velocity (°/s) Trunk Rotation Velocity (°/s) Ball Release Shoulder Internal Rotation (°) Elbow Extension (°) Trunk Forward Tilt (°) Performance Ball Velocity (m/s) Pop time (s) Time to second base (s) Stride Length (m). 135.1 ± 12.9 22.2 ± 9.2 99.0 ± 13.0 126.7 ± 8.6 11.5 ± 5.7. 138.4 ± 12.8 21.7 ± 10.7 102.1 ± 9.7 126.4 ± 8.5 19.7 ± 5.4. 137.5 ± 11.9 20.2 ± 10.9 102.3 ± 10.1 126.2 ± 7.3 18.3 ± 5.2. 20.2 ± 2.9. 1904.9 ± 234.9 360.5 ± 40.9. 20.7 ± 4.0 1063.4 ± 188.8 2047.4 ± 219.5 300.8 ± 39.3. 20.7 ± 4.3 1032.1 ± 201.6 2007.3 ± 202.9 288.7 ± 44.5. 15.2 ± 8.4 23.3 ± 11.2 8.9 ± 4.2. 14.0 ± 7.8 22.3 ± 12.3 6.5 ± 4.3. 14.6 ± 8.7 21.1 ± 11.3 6.0 ± 4.8. 27.7 ± 2.2 0.73 ± 0.1 2.14 ± 0.1 N/A. 29.9 ± 2.8 0.79 ± 0.1 2.10 ± 0.1 1.22 ± 0.1 70.1% ± 2.0%. 31.4 ± 2.6 0.77 ± 0.1 2.02 ± 0.2 1.20 ± 0.1 68.9% ± 2.0%. 1024.4 ± 132.7. Stride Length, % of height N/A Note. Values are mean ± SD (n=11) , p < .05.. . Pitch out c. Observed Differenc es a,b,c a & c, b & c a&c a,b,c. a,b,c a,b,c. a,c a,b,c a & b, a &c a & c, b & c. 28 .

(35) In the arm acceleration phase of the throwing motion, only elbow extension and trunk rotation velocities exhibited significant differences. When the velocity of elbow extension was measured, the traditional throw down was faster than the other motions in the study, with an average velocity of 2047.4 ± 219.5 degrees per second. The pitch out recorded the second highest average elbow extension velocity of 2007.3 ± 202.9 degrees per second, and the knee averaging the slowest velocity of 1904.9 ± 234.9 degrees per second. Rotation velocities of the trunk from fastest to slowest ranks as follows: throwing from the knees, traditional throw down, and finally the pitch out, with velocities of 360.5 ± 40.9, 300.8 ± 39.3, and 288.7 ± 44.5 degrees per second, respectively.. *. Angular Velocity (° /s). 400. 300. 200. 100. 0. Throwing from the knees. . Traditional throw down. Pitch out. 29 .

(36) Figure 4-3. Trunk angular velocity measurements for the three throwing positions. Differences were not observed for shoulder internal rotation velocity and trunk extension. As the ball was released, the pitch out and knee positions significantly differed in trunk forward tilt angles, with the kneeling throw demonstrating 8.9 ± 4.2 degrees of forward tilt. Shoulder internal rotation and elbow extension angles were similar and yielded no differences.. Table 2 Correlation Between Joint Kinematics and Throwing Motions Parameters. Shoulder Max Extension. Throwing from the knees Ball Pop Velocity Time. Traditional throw down. Pitch out. Ball Velocity. Pop Time. Ball Velocity. Pop Time. 0.056. 0.172. 0.049. 0.274. 0.224. 0.114. Shoulder Max External Rotation. 0.327 *. 0.479 *. 0.362 *. 0.437 *. 0.306 *. 0.654 *. Shoulder Max Internal Rotation. 0.126. -0.348 *. 0.099. -0.006. 0.227. -0.388 *. Shoulder Max Abduction. 0.261 *. 0.029. 0.615 *. -0.378 *. 0.503 *. -0.216. Elbow Max Flexion. -0.042. -0.142 *. 0.159. -0.486 *. 0.018. -0.179. Elbow Max Extension. 0.205. 0.419 *. 0.446 *. 0.017. 0.498 *. 0.195. -0.312 *. -0.218. -0.173. -0.161. -0.051. -0.177. -0.303 *. -0.059. -0.276 *. -0.416 *. 0.14. -0.406. -0.052. 0.374 *. -0.038. 0.489 *. -0.347 *. 0.585 *. Trunk Max Extension Trunk Max Forward Tilt Trunk Lateral Tilt Shoulder Internal Rotation Velocity Elbow Extension Velocity. 0.446 *. 0.139. 0.235. 0.294 *. 0.155. 0.177. -0.295 *. -0.63 *. -0.364 *. -0.468 *. -0.268 *. -0.549 *. Trunk Angular Velocity. 0.237 *. 0.237 *. 0.1. 0.21. 0.069. 0.018. Note. Observed differences p <.05. . 30 .

(37) Figure 4-4. Relationship between traditional throw down kinematic parameters and ball velocity. R2 = 0.672.. Figure 4-5. Relationship between pitch out kinematic parameters and ball velocity. R2 = 0.624.. . 31 .

(38) The kinematics was further analyzed for influences on ball velocity and pop time with p < .05. The traditional throw down reported an R-value of 0.820 and R2 of 0.672 for ball velocity. The pop time’s R-value and R2 for ball velocity are 0.835 and 0.696, respectively. Shoulder abduction, elbow max extension, and shoulder external rotation positively correlated with ball velocity. Conversely, forward tilt of the trunk and elbow extension velocity negatively correlated with the traditional throw down’s ball velocity. Analyzing pop time, shoulder external rotation and lateral tilt of the trunk to the left were positively correlated. While angles of the shoulder abduction, elbow flexion, trunk forward tilt, and elbow extension velocity negatively correlated with pop time. Throwing to second base via the pitch out produced an R-value of 0.790 and R2 of 0.624 for ball velocity, and an R-value of 0.801 and R2 of 0.642 for the pop time. Shoulder external rotation, shoulder abduction, and elbow extension displayed positive correlation, while trunk tilt to the left and elbow extension velocity negatively correlated with the pitch out’s ball velocity. Pop time exhibited positive correlations with shoulder external rotation and trunk lateral tilt to the left. Negative correlation between the pitch out and pop time were observed for shoulder internal rotation and elbow extension velocity. From the kneeling position, seven parameters had statistically significant correlations with the ball velocity and pop time when p < .05. The reported R-value and R2 values for ball velocity were 0.446 and 0.199, respectively. The pop time had an R-value of 0.750 and R2 of 0.562. Of the seven parameters, shoulder max external rotation, abduction, internal rotation velocity, and trunk angular velocity were positively correlated with the ball velocity. However, when the shoulder internal rotation angle, elbow flexion angle, and elbow extension velocity increases, the ball’s velocity will see a decreased value due to the negative correlation observed. . 32 .

(39) Pop time displayed a positive relationship with shoulder external rotation, trunk tilt to the left, and trunk angular velocity. Nevertheless, shoulder internal rotation, elbow flexion, and elbow extension velocity negatively impacted the pop time.. . 33 .

(40) Chapter 5 – Discussion Catchers play an integral role of defending against base runners. When the runner is attempting to steal second base, catchers first must receive the pitched ball in a deep crouched position. As the ball is caught, the catcher then simultaneously rises up from the squatted position and transfers the ball to the throwing hand. The catcher then externally rotates the shoulder to its maximum and proceeds to internally rotate the shoulder, extending the elbow at high velocities to throw the ball. Having a quick pop time, defined as when the ball is caught to being released, and fast ball velocity increases the probabilities of catching base runners at second base. The caught stealing percentage, a performance statistic often highly coveted amongst baseball scouts, is calculated via: caught stealing / (stolen bases + caught stealing). Catchers endeavor to increase this percentage with the aid and training from their coaches. Thoroughly understanding the catcher’s throwing motion provides an additional asset to assist in the training and improvement of performance. Three commonly seen techniques throwing to second base are: the traditional throw down, the pitch out, and throwing from the knees. The conventional method for throwing down to second base to catch base stealers is the traditional throw down. It is generally assumed amongst the baseball community is that on average, the pitch out would produce the fastest ball velocities, pop time, and total time to second base when utilized to throw down to second base. The pitch out, an unimpeded throw to second base, is frequently seen as the most quintessential strategy to throw out a runner stealing second (Fortenbaugh et al., 2010). Kneeling and throwing to second is assumed to have the quickest pop times.. . 34 .

(41) This study investigated three throwing motions used by catchers throwing to second base, the potential differences in joint kinematics, and the effects on player performance. Professional catchers performed the required throwing tests in the research. Joint kinematics for the upper extremities as well as the pelvis for all test participants were scrutinized. Further analysis of the throws and its kinematic values drew plausible influences on player performance. Prospective training and intervention methods could be introduced to enhance performance values. Joint Kinematics The catcher’s ball speed and quickness is imperative to how successfully a runner is thrown out at second base, due to this, throwing mechanics could potentially be more concise (Fortenbaugh et al., 2010; Plummer & Oliver, 2013; Kibler, 1998). Upon analysis of the performance value of ball velocity, the pitch out registered the highest average ball velocities, recording velocities averaging 31.4 meters per second (113 km/h), when throwing down to second base. Although this study was only capable of explaining roughly sixty to sixty-seven percent of possible joint kinematic factors influencing ball velocity, other previous studies have produced similar findings as well (Fortenbaugh & Fleisig, 2009; Matsuo et al., 2001; Fortenbaugh & Fleisig, 2010; Fortenbaugh et al., 2010). Shoulder external rotation, trunk forward, and lateral tilt angles, as well as elbow extension, shoulder internal rotation, and trunk rotation velocities, plausible influencing kinematic factors for ball velocity, however, were significantly lower than traditional throw down measurements. The traditional throw down could possibly have exhibited higher shoulder external rotation angles to generate more ball velocity. Previous research scrutinizing pitching mechanics and efficiency produced contradicting results.. . 35 .

(42) Efficient pitchers were able to generate greater trunk and shoulder rotation velocities, thus throwing the ball faster, when compared to pitchers with inefficient mechanics (Fortenbaugh & Fleisig, 2009). More pronounced trunk rotation could possible give pitchers and catchers a greater ability to maximally externally rotate the shoulder, which is often associated with increases in throwing velocity (Fortenbaugh & Fleisig, 2009; Matsuo et al., 2001; Oyama et al., 2014). It was proposed that the pitch out would require the least amount of trunk rotation velocity, followed by the traditional throw down requiring more, while throwing from a kneeling position would require the most amount of trunk rotation velocity. Significant differences can be seen in the trunk rotation velocity for all three throwing motions. Due to the throwing motion characteristics of the traditional throw down, rising from a crouched position to the concise footwork to turn the body towards second base and then throwing the ball, an increased trunk rotation velocity is probably more prevalent than the pitch out (Fortenbaugh & Fleisig, 2009; Plummer & Oliver, 2013). As opposed to the traditional throw down, the pitch out begins the throwing motion already risen out of the squatted position, ready to catch the ball and then step and throw to second base; side-by-side comparisons can be seen in the two figures below (Fortenbaugh & Fleisig, 2010). This forward movement motion occurring prior to the throw for the pitch out, versus the more stationary position of the traditional throw down, perchance relies less on trunk rotation while displaying a throwing motion utilizing more forward momentum, thus generating faster ball velocities. Resulting differences during the throw itself can arise due to the forward movement involving the entire body moving in a coordinated manner prior to throwing the ball (Hussain & Bari, 2011). Throwing from the knees impedes the catcher from utilizing the lower extremity to generate sufficient forces necessary to deliver the ball to second base effectively. . 36 .

(43) Consequently, it can be hypothesized that from this kneeling position, an increased trunk rotation velocity with additional forward lean of the trunk is imperative. Pitchers and position players strive for accurate and high velocity throws thus are often found to lean into their throws; likewise, a catcher flexes the trunk forward and extending the elbow to amplify the energy to propel the ball towards second base with a whip like effect in the throwing arm (Escamilla et al., 2012; Fortenbaugh & Fleisig, 2009). Achieving this whip like effect would presumably have faster elbow extension velocities, while a motion that relies on pre-throw movements such as the pitch out would not necessitate as much. In spite of variations of the throwing motion, kneeling and throwing to second base would produce the slowest ball velocities, fundamentally compromising the total time to second base. Kinematic factors known to influence ball velocity were less pronounced from the pitch out. Nonetheless, upper extremity kinematics can only partially explain ball velocity influencing elements. Analysis of pop time and the total measured time to second base revealed that the traditional throw down was slower than the pitch out. By professional baseball scouting standards, the desired total time, from catching the pitched ball to the ball being caught at second base after the catcher has thrown it, should be within 2.0 seconds (Sakurai et al., 1994). Striving to improve ball release times, catchers will often throw to second base from a kneeling position (Plummer & Oliver, 2011). Consistently between the three motions, shoulder external rotation degrees displayed positive relationships with pop time, while elbow extension velocity had negative correlations. Abducting the shoulder too much also had detrimental effects to the pop time. This could be due to the extra distance the arm needed to travel, thus increasing the time needed. Nevertheless, as a result of the concise motion, the kneeling position is able to clock in the fastest pop time when compared with the other two throwing motions.. . 37 .

(44) The kinetic chain and stretch shortening cycle (SSC) and potential implications The throwing motion acts in sequence to complete a chain of events from most proximal body segments to the most distal segments. This coordinated movement allows the body to generate and transfer the required energy to throw the baseball (Plummer & Oliver, 2013; Kibler, 1998). The transfer of energy in sequence from proximal to distal segments is often referred to as the kinetic chain (Zaremski & Krabak, 2012). Maximizing the ball velocity by virtue of this could pose as a beneficial tool to reduce strains on the throwing arm (Fortenbaugh & Fleisig, 2009; Fortenbaugh et al., 2009). It is conceivable that from the pitch out, the catcher is able to sequence the body segments from the lower to upper extremities prior to throwing while moving forward to generate forward momentum, together utilize the transfer of energy by means of the kinetic chain (Fortenbaugh & Fleisig, 2009; Matsuo et al., 2001). Increases in ball velocities could result if the kinetic chain is proficiently used during the throwing motion (Fortenbaugh & Fleisig, 2009). It is believed that the safest and most methodical transfer of energy by effectively timing this chain which begins from the lower body, through the trunk, and finally into the upper limbs, and exiting into the ball (Davis et al., 2009; Urbin et al., 2013; Fortenbaugh, Fleisig, & Andrews, 2009; Aguinaldo, Buttermore, & Chambers, 2007). The traditional throw down perhaps lacks the optimal transfer of energy from the lower body segments to the upper body, attributed to the rushed throwing motion requiring a quick hop to turn the body while compacting throwing movements when throwing the ball. The demand for the least amount of time required to throw to second base could undermine methodical throwing mechanics, thus could impart higher forces on the shoulder and elbow structures (Fortenbaugh & Fleisig, 2009; Fortenbaugh & Fleisig, 2010; Plummer & Oliver, 2013; Kibler, 1998; Dun et al., 2008). Due to. . 38 .

(45) time limitations to throw out a base runner, catchers could potentially trade off biomechanical efficiency and opt for quicker, shorter motions when under duress (Fortenbaugh et al., 2010). The upper extremity transfer of kinetic energy occurs predominantly during the arm cock phase. Flexing the elbow during this phase allows passive inertial forces to assist in the external rotation of the shoulder. As the shoulder externally rotates further to its maximum, more time is allotted to produce and accumulate energy in the elastic soft tissues and muscle fibers that cross the shoulder complex. (Roach et al., 2013). Recoiling of the elastic elements will rapidly drive the shoulder to internally rotate and extend the elbow and create the high-powered movement necessary for overhead throwing (Roach et al., 2013). The elastic components in the body utilizes the stretch-shortening cycle, the coupling of muscle eccentric and concentric movements, which stimulates the body’s proprioceptors allowing the muscle to recruit more fibers to produce maximal force in the shortest given amount of time (Wilk et al., 1993; Carter et al., 2007). Greater concentric forces can be produced when the muscle loads eccentrically faster because when the elastic elements are stressed more rebound forces are more readily available (Wilk et al., 1993). If an overhead athlete, such as a catcher, is able to abduct and rotate the shoulder externally further, faster ball velocities can be produced when the ball is released (Baker & Ayers, 2014). Storing elastic energy in shoulder ligaments and tendons, however, has possible injury implications in both the shoulder structure as well as the elbow due repeated use and the high-energy transfer (Roach et al., 2013; Baker & Ayers, 2014; Byram et al., 2010). When the coordinated chain of events for throwing is established and sequenced efficiently, forces to the throwing arm can possibly be minimized and injury risks resulting from pathomechanics reduced (Plummer & Oliver, 2013). Microtraumas to shoulder components and soft tissues often surface due to continuous stressing of the shoulder structures, overuse injury and the thrower repeatedly. . 39 .

(46) trying to gain extra power during the throwing motion (Park et al., 2002; Urbin et al., 2012; Chu et al., 2009; Oyama et al., 2014). Additionally, shoulder internal impingement symptoms could be credited to excessive external rotations when the shoulder is fully abducted during the throwing motion (Fleisig et al., 2011). If the catcher is unable to reach an ideal shoulder elevation during the throwing motion, added stresses could be placed on the shoulder and the elbow, ultimately leading to upper extremity injuries (Plummer & Oliver, 2011). If the overhead throwing athlete improperly sequences trunk rotation events, increases in shoulder external rotation angles could occur to compensate for a loss of additional muscular strength, which could predispose the thrower to shoulder injuries (Oyama et al., 2014). The ability to properly sequence the trunk could be instrumental in protecting the thrower’s shoulder (Oyama et al., 2014). Inefficient sequencing of body segments and mechanics during the throwing motion poses as inherent risks of injury for the overhead thrower (Plummer & Oliver, 2011; Oyama et al., 2014). Presuming that the timing of the coordinated events in the kinetic chain does not occur, higher joint kinematics and kinetics could be produced in order to compensate for momentum loss that is needed to sustain necessary ball velocities (Urbin et al., 2013). Applications Comprehending joint kinematics for catchers throwing to second base can provide training support to coaching staff and trainers. Based on the findings from this study, when throwing to second base, the pitch out was the fastest in relation to the total time to second base as well as ball velocities. The general assumption that the pitch out is the quickest method to impede attempted stolen bases at second was validated in this study. Nonetheless, steps can still be taken to improve performance. Since ball velocity highly influences the overall elapsed time to second base, slightly slower pop times will not hinder overall performance. From the results of . 40 .

(47) the study, although the pitch out produced a significantly slower pop time than throwing from a kneeling position, the pitch out was still able to produce the quickest overall time to second base. It is with this notion that increasing ball velocity should be a priority for catchers. Increases in certain joint kinematic parameters have shown positive relationships with increases in ball velocity for each of the three throwing motions. As the catcher prepares to throw, rotating the shoulder externally further will allow more energy to be stored in the elastic elements of the shoulder muscle complex (Baker & Ayers, 2014; Roach et al., 2013; Carter et al., 2007; Wilk et al., 1993). Consequently, with more shoulder external rotation and abduction, faster velocities will be produced when the ball is thrown by means of the pitch out, traditional throw down, and throwing from the knees (Baker & Ayers, 2014). If the catcher is additionally able to have increased rotation velocities and flexion angles of the trunk, while explosively extending the elbow during the arm acceleration phase of the throwing motion, ball velocities can also potentially increase (Escamilla et al., 2012; Fortenbaugh & Fleisig, 2009). Throwing from a kneeling position’s ball velocity significantly benefits from an increase in trunk rotation velocity. However, trunk tilting the trunk too far to the left will impede the catcher from generating faster ball velocities. It can be recommended that catchers lacking shoulder and trunk flexibility collaborate with their respective training staff to safely improve the range of motion for shoulder external rotation as well as overall trunk rotation. Additionally, with the training staff, it is advisable that trunk rotation exercises also be performed to safely improve rotation velocities. During the course of a baseball game, if a base runner is attempting to steal second base, it is recommended that the pitch out be implemented if it will not result in a base on balls. When compared to the other two throwing motions, throwing from the knees and traditional throw . 41 .