of Arkansas, Fayetteville, 72701, United States b Auburn University, Department of Kinesiology, Auburn, Alabama, 36830, USA

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1 This article was downloaded by: [Auburn University] On: 18 February 2013, At: 08:09 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: Registered office: Mortimer House, Mortimer Street, London W1T 3JH, UK Journal of Sports Sciences Publication details, including instructions for authors and subscription information: Quantitative analysis of kinematics and kinetics of catchers throwing to second base Hillary Plummer a b & Gretchen Dawn Oliver a b a University of Arkansas, Health, Kinesiology, Recreation, and Dance, HPER 309, University of Arkansas, Fayetteville, 72701, United States b Auburn University, Department of Kinesiology, Auburn, Alabama, 36830, USA Version of record first published: 18 Feb To cite this article: Hillary Plummer & Gretchen Dawn Oliver (2013): Quantitative analysis of kinematics and kinetics of catchers throwing to second base, Journal of Sports Sciences, DOI: / To link to this article: PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.

2 Journal of Sports Sciences, Quantitative analysis of kinematics and kinetics of catchers throwing to second base HILLARY PLUMMER & GRETCHEN DAWN OLIVER* University of Arkansas, Health, Kinesiology, Recreation, and Dance, HPER 309, University of Arkansas, Fayetteville, United States (Accepted 11 January 2013) Downloaded by [Auburn University] at 08:09 18 February 2013 Abstract The catcher has the most demanding position in the games of baseball and softball with no regulations on how many throws they make during game. It was the purpose of this study to describe the kinematics and kinetics of the throwing motion in catchers when throwing down to second base. It was hypothesised that younger and older catchers would display significantly different throwing kinematics and kinetics. Thirty-eight baseball and softball catchers volunteered to participate. Twenty participants were considered younger (aged 9 14, ± 1.76 years, ± cm, ± kg) and 18 were deemed the older group (aged 15 23, ± 2.61 years, ± 8.67 cm, ± kg). Participants received a pitch and completed five accurate throws to second base in full catching gear. The average ball speed of the older catchers was 21 ± 3.58 meters per second (47 ± 8.02 mph) while the younger catchers averaged 17.2 ± 4.0 meters per second (38.6 ± 8.96 mph). Older catchers had greater shoulder elevation at ball release and significantly greater shoulder external rotation at foot contact and shoulder maximum external rotation than younger catchers. It is clear that chronological age plays a role in the throwing mechanics observed in catchers throwing down to second base, however the effects of these differences are not fully understood (i.e., skeletal maturity, experience, strength). Keywords: baseball, kinetic chain, overhead throwing, softball Introduction The kinematics and kinetics of baseball pitching have been well documented (Dapena, 1978; Escamilla, Fleisig, Barrentine, Zheng, & Andrews, 1998; Feltner & Dapena, 1986; Fleisig, Andrews, Dillman, & Escamilla, 1996; Fleisig, Escamilla, Andrews, Matsuo, Satterwhite et al., 1996; Keeley, Hackett, Keirns, Sabick, & Torry, 2008) while those of softball are beginning to evolve (Oliver, Dwelly, & Kwon, 2010; Oliver & Plummer, 2011; Rojas, Provencher, Bhatia, Foucher, Bach et al., 2009; Werner, Gill, Murray, Cook, & Hawkins, 2001; Werner, Guido, McNeice, Richardson, Delude et al., 2005; Werner, Jones, Guido, & Brunet, 2006). The great interest in baseball pitching is that it is the most dynamic human movement thus placing the upper extremity at increased risk of injury (Fleisig, Barrentine, Escamilla, & Andrews, 1996). The primary focus in the literature has been baseball pitching with increased interest evolving for softball. More interest has advanced due primarily to the increased participation within both sports. Little League has reported that in 2010 there were a total of 2,513,760 participants in both baseball and softball, (Little League, 2011) while the Amateur Softball Association reports an annual participation of 1.2 million girls (Amateur Softball Association, 2010). Any time there is a rise in participation there also is a concern for an increase in injury susceptibility. Thus in an attempt to decrease injury prevalence, often we are exploring injury predictive mechanisms or injury prevention programmes to deter injury. Recently a 10-year prospective study examined injury predictors in 481 youth baseball pitchers (Fleisig, Andrews, Cutter, Weber, Loftice et al., 2011). It was revealed that ultimately youth who throw more than 100 innings in a year are at a significantly higher risk of being injured. In addition, those youth who concomitantly played catcher also had an increase in injury rate. The greater inquiry was the fact that of the 481 youth who were pitching at the start of the study, only 2.2% were pitching 10 years later (Fleisig et al., 2011). Besides the increase in injury to pitchers, there is also an injury concern for catchers. The position of catcher predisposes overuse injury implications due to the Correspondence: Gretchen Dawn Oliver, Auburn University, Department of Kinesiology, Auburn, AL United States. gretchendoliver@gmail.com *Both authors are currently affiliated to: Auburn University, Department of Kinesiology. Auburn, Alabama Taylor & Francis

3 Downloaded by [Auburn University] at 08:09 18 February H. Plummer & G. D. Oliver number of throws completed during an average game. Of the two positions, pitcher and catcher, the catcher is the one who most often plays the entire game without limitations or restrictions on number of throws allowed while pitchers are restricted by pitch count. The position of catcher exhibits a unique position during throwing that could encourage pathomechanics. Catchers make more throws in a game than any other position player. It is the goal of the catcher to catch the pitched ball from their squatted position, and have quick ball transfer, from their glove, to their throwing hand in attempt to throw to second base to prevent the runner from stealing. Additionally, the catcher is responsible for holding the base runner on base, and to do this they must also deal with indiscriminate variables such as having to receive a low pitch, and wait for the batter to complete their swing, as well as the restrictions of their protective equipment. Regardless of the sport, baseball or softball, the catcher is the critical element in controlling the flow of the game. Currently there is only one study examining the biomechanics describing the throwing motion of catchers (Sakurai, Elliott, & Grove, 1994). From a coaching perspective, it is known that catchers are instructed to be quick on their feet, have their nonthrowing shoulder in line with the target, and produce an abbreviated throwing pattern (American Baseball Coaches Association, 2001). Therefore it was the purpose of this study to describe the kinematics and kinetics of the throwing motion of both baseball and softball catchers when throwing to second base, in addition examining kinematic and kinetic differences between two different age groups. It was hypothesised that the younger and older catchers would display significantly different throwing kinematics and kinetics. Methods Study design A descriptive study was implemented for the current study. Thirty-eight baseball and softball catchers (14.34 ± 4.22 years, ± 16.5 cm, ± kg) volunteered to participate. Participants were divided into two groups (younger and older) based on their age. Twenty participants were determined to be younger (Aged 9 14, ± 1.76 years, ± cm, ± kg), with three females (11 ± 1 years, ± 8.96 cm, ± 13.75) and 17 males (10.94 ± 1.89 years, ± cm, ± 19.92). Eighteen participants were placed in the older group (Aged 15 23, ± 2.61 years, ± 8.67 cm, ± kg) with 15 females (18.4 ± 2.67 years, ± 7.37 cm, ± 11.07) and three males (16.67 ± 1.69 years, ± 0 cm, ± 5.96 kg). Both baseball and softball catchers were recruited for the study since the throwing motions of a baseball and softball catcher are similar in nature. Catchers in both sports receive a pitch, in a squatted position, and quickly transfer the ball to their throwing hand in order to throw out a stealing runner. While the distance to second base is different between the sports the level of difficulty of the throw is believed to be comparable. In baseball the distance between bases is greater but runners are allowed to lead off and steal before the pitcher releases the ball giving the base runner an advantage over the catcher. However, in softball the distance between bases is shorter but the base runner is not allowed to leave the base until the pitcher has released the ball. All participants had recently finished their competitive season, and were deemed appropriately conditioned for participation. Additional criterion included coaching staff recommendation, multiple years (up through the current season) of catching experience, and freedom from injury throughout their recently completed season. Throwing arm dominance was not a factor contributing to participant selection or exclusion. The University s Institutional Review Board approved all testing protocols used in the current study, and prior to participation the approved procedures, risks, and benefits were explained to all participants. Informed consent was obtained from the participants, and the rights of the participants were protected according to the guidelines of the University s Institutional Review Board. Participants reported for testing prior to engaging in resistance training or any vigorous activity that day. Data were collected in a gym inside the University s Health, Physical Education, and Recreation building. Kinematic data were collected using The MotionMonitor TM motion capture system (Innovative Sports Training, Chicago, IL). Participants had a series of 10 electromagnetic sensors (Flock of Birds Ascension Technologies Inc., Burlington, VT) attached at the following locations: (1) the medial aspect of the torso at C7; (2) medial aspect of the pelvis at S1; (3) the distal/posterior aspect of the throwing humerus; (4) the distal/posterior aspect of the throwing forearm; (5) the distal/ posterior aspect of the non-throwing humerus; (6) the distal/posterior aspect of the non-throwing forearm; (7) the distal/posterior aspect of stride leg shank; (8) the distal/posterior aspect of the stride leg femur; (9) the distal/posterior aspect of the non-stride leg shank; and (10) the distal/posterior aspect of the non-stride leg femur (Myers, Laudner, Pasquale, Bradley, & Lephart, 2005). Sensors were affixed to the skin using double sided tape and then wrapped using flexible hypoallergenic athletic tape to ensure

4 Downloaded by [Auburn University] at 08:09 18 February 2013 proper placement throughout testing. Following the attachment of the electromagnetic sensors, an 11th sensor was attached to a wooden stylus and used to digitise the palpated position of the bony landmarks (Myers et al., 2005; Oliver & Plummer, 2011; Wu, Siegler, Allard, Kirtley, Leardini, et al., 2002). Participants were instructed to stand in anatomical neutral while selected bony landmarks were accurately digitised. A link segment model was developed through digitisation of joint centres for the ankle, knee, hip, shoulder, T12-L1, and C7-T1. The spinal column was defined as the digitised space between the associated spinous processes, whereas the ankle and knee were defined as the midpoints of the digitised medial and lateral malleoli, and medial and lateral femoral condyles, respectively. By virtue of the least squares method, the hip and shoulder joint centres were defined (Meskers, Vermeulen, de Groot, van Der Helm, & Rozing, 1998). Following all set-up and pre-testing protocols, participants were allotted an unlimited time to perform their own specified pre-competition warm-up routine. Warm-up and test trials were conducted with the participants wearing their full catchers gear consisting of a facemask, chest protector, and shin guards in order to best simulate a competitive environment. Testing consisted of the participant positioned behind the home plate catching a fastball pitched from a designated pitcher. Once the participant caught the pitch, they were instructed to throw to the position player at second base. Each participant had to complete five accurate throws to second base, with an accurate throw defined as the position player s ability to catch the throw without stepping off the base. Those data from the fastest throw to second base were selected for detailed analysis (Oliver & Keeley, 2010a, 2010b; Rojas et al., 2009). Throwing speed was determined by a JUGS radar gun (OpticsPlanet, Inc., Northbrook, IL) positioned at the base of the home plate directed towards second base. Raw data regarding sensor orientation and position were transformed to locally based coordinate systems for each of the respective body segments. Euler angle decomposition sequences were used to describe both the position and orientation of the torso relative to the global coordinate system (Wu et al., 2002; Wu, Van Der Helm, Veeger, Makhsous, Van Roy, et al., 2005). The use of these rotational sequences allowed the data to be described in a manner that most closely represented the clinical definitions for the movements reported (Myers et al., 2005). Data reduction Data at foot contact (FC), maximum external rotation (MER), ball release (BR), and maximum internal rotation (MIR) were analysed (Figure 1). Foot Figure 1. Phases of throwing. Kinematics and kinetics of catchers 3 contact was determined by the time the stride leg touched the force plate during the throw. The next point in time analysed was maximum external rotation of the throwing shoulder. Ball release was determined as the middle frame between MER and MIR. The last point in time analysed was maximum internal rotation of the shoulder. The dependent variables that were selected for analysis were trunk flexion, trunk lateral flexion, trunk axial rotation, shoulder plane of elevation, shoulder elevation, shoulder rotation, elbow flexion, pelvis lateral flexion, pelvis rotation, shoulder anterior force, shoulder moment, hip speed, trunk speed, shoulder speed, forearm speed, and elbow moment. Data analysis Data were analysed in the current study using the statistical analysis package SPSS 17.0 for Windows. A two group multivariate analysis of variance (MANOVA) was conducted to determine statistical significance between kinematic and kinetic variables in younger and older catchers. The dependent variables were analysed separately at FC, MER, BR, and MIR. If significance was detected follow-up independent samples t tests were conducted to determine the point in the throwing motion where differences were observed. The level of significance was set aprioriat P <0.05. Results It was the purpose of this paper to examine overall throwing kinematics and kinetics of the entire sample and to also examine if any differences occurred between younger and older catchers. The overall average speed of the selected throws for analysis was ± 4.21 meters per second (42.58 ± 9.43 miles per hour). The average speed for the younger catchers was (17.2 ± 4.00 meters per second; 38.6 ± 8.96 mph) while the older catchers threw (21.01 ± 3.59 meters per second; 47 ± 8.02 mph). Kinematic data of the entire sample are presented in Table I. Both younger and older group kinematic and kinetic data are presented in Table II and Table III, respectively. Shoulder elevation

5 4 H. Plummer & G. D. Oliver Downloaded by [Auburn University] at 08:09 18 February 2013 Table I. Kinematic data of entire sample. Mean (Standard Deviation). Trunk Flexion Trunk Lateral Flexion Trunk Axial Rotation Plane of Elevation Elevation Shoulder Rotation Elbow Flexion Pelvis Lateral Flexion Pelvis Rotation (( ) is flexion) ((+) is to the right) ((+) is to the left) (0 is ABD & 90 is forward flexion) (0 = Full ABD while 90 = 90 ABD) ((+) is internal rotation) ((+) is flexion) ((+) is to the right) (( ) is to the right) FC (11.80) (15.29) (16.55) (21.48) (21.11) (30.49) (16.05) (8.18) (17.20) MER (12.80) (11.58) (15.92) (22.09) (17.83) (23.70) (35.04) (7.00) (12.12) BR (15.83) (11.78) (13.62) (19.49) (19.86) (25.21) (19.15) (7.22) (10.89) MIR (16.84) (12.36) (14.46) (24.36) (15.67) (33.29) (14.55) (7.13) (10.97) ABD = abduction.

6 Kinematics and kinetics of catchers 5 Downloaded by [Auburn University] at 08:09 18 February 2013 Table II. Younger and older kinematic data. Mean (Standard Deviation). Trunk Flexion Trunk Lateral Flexion Trunk Axial Rotation Plane of Elevation Elevation Shoulder Rotation Elbow Flexion Pelvis Lateral Flexion Pelvis Rotation (( ) is flexion) 95% CI ((+) is to the right) 95% CI ((+) is to the left) 95% CI (0 is ABD &90is forward flexion) 95% CI (0= Full ABD while 90 =90 ABD) 95% CI ((+) is internal rotation) 95% CI ((+) is flexion) 95% CI ((+) is to the right) 95% CI (( ) isto the right) 95% CI FC Group * (11.81) (12.20) 5.8 (17.87) (20.51) 8.56 (18.25) (32.37) (16.08) (8.96) (18.81) Group * (12.13) (17.74) (15.13) (16.27) (24.29) (24.90) (16.18) (7.32) (15.62) MER Group * (13.10) (9.80) 5.68 (19.35) 2.32 (20.91) (14.20) (24.12) (45.28) (7.97) 5.93 (14.49) 6.44 Group * /62 2 (11.85) (13.29) 0.05 (11.53) 0.32 (22.85) (20.34) (18.34) (19.41) (5.93) 7.56 (8.86) 7.56 BR Group * (15.38) (12.09) (15.86) (19.11) (14.31) (26.79) (18.22) (7.99) 9.61 (11.66) Group * (15.74) 8.54 (11.62) (11.04) (18.92) (22.08) (24.05) (18.35) (6.45) 9.44 (10.19) MIR Group (16.79) 7.98 (12.70) (15.16) (23.66) (14.14) (39.37) (11.35) 25.3 (7.61) (10.37) Group (17.13) 4.65 (11.97) (13.78) (19.27) (16.70) (25.72) (17.43) (6.53) 9.28 (11.82) * within cells, indicates statistical significance. P % CI = 95% Confidence Interval.

7 6 H. Plummer & G. D. Oliver Downloaded by [Auburn University] at 08:09 18 February 2013 Table III. Younger and older kinetic and segmental velocity data. Mean (Standard Deviation). Shoulder Anterior Force (N) 95% CI Shoulder Moment (N) 95% CI Elbow Moment (N) 95% CI Hip Speed (rad sec -1 ) 95% CI Trunk Speed (rad sec -1 ) 95% CI Shoulder Speed (rad sec -1 ) 95% CI Forearm Speed (rad sec -1 ) 95% CI FC Group * (24.46) (3.67) 6.28 (0.96) 0.23 (1.93) 3.50 (1.98) 3.58 (4.35) 8.54 (4.61) Group * (65.41) (7.62) (3.31) 1.31 (0.71) 2.22 (1.32) 3.07 (2.91) 8.66 (7.62) MER Group * (128.68) (16.70) 7.93 (9.62) 4.39 (2.68) 8.09 (2.38) (5.57) (10.35) Group * (229.37) (69.22) (19.25) (3.04) 8.25 (2.38) (6.13) (7.36) BR Group * * * (142.38) (34.57) (9.96) 0.62 (1.87) 3.28 (3.29) 9.04 (18.81) (13.94) Group * * * (335.71) (100.52) (23.21) 9.31 (1.07) 3.14 (2.02) ) (8.56) MIR Group * * * (142.50) (26.27) (12.65) (2.21) 3.91 (1.78) 5.42 (12.24) (14.07) Group * * * (265.15) (84.89) (12.36) (1.25) 2.91 (2.34) 5.69 (11.21) (10.70) * within cells, indicate statistical significance. p 0.05.

8 Downloaded by [Auburn University] at 08:09 18 February 2013 demonstrated significant group differences, Wilks Lambda = 0.601; F (30, ) = 1.84; P = The older catchers had greater shoulder elevation at BR than the younger catchers (d = 0.87). Differences in shoulder rotation between the two groups of catchers were evident early in the throwing motion. At both FC and MER older catchers had significantly greater shoulder external rotation than the younger catchers (d = 0.74 and d = 0.99, respectively). Hip, trunk, shoulder, and forearm speed were not statistically different throughout the throwing motion. Moments about the shoulder and elbow did show statistical significance. Shoulder moments demonstrated significant differences between groups, Wilks Lambda = 0.524; F (24, ) = 3.05; P < Older catchers had significantly greater shoulder moment at FC (P < 0.05, d = 0.78), BR (P <0.05, d = 0.80), and MIR (P < 0.001, d = 1.09). Additionally, older catchers also had greater elbow moment at MER (P <0.001, d = 1.29), BR (P = 0.01, d = 0.92), and MIR (P < 0.001, d = 1.38). Discussion The popularity of youth participation in baseball and softball make our awareness and understanding of proper mechanics and pathomechanics fundamental in the realm of sports medicine. Just as in pitching, the catcher has to rotate his or her trunk to face their target, externally rotate their shoulder and flex their elbow. Then they reach maximum shoulder external rotation, and elbow flexion to rapidly accelerate to internal shoulder rotation and elbow extension for ball release. The ability to properly sequence these events during the throwing motion is essential to limit the forces acting on the upper extremity and prevent injury that may occur due to improper sequencing (Bunn, 1972; Putnam, 1993). Fortenbaugh and colleagues have presented data of collegiate catchers reporting that they had shorter stride, reduced pelvic-trunk separation and greater elbow flexion in cocking as compared to pitchers and position players (Fortenbaugh, Fleisig, & Bolt, 2010). The results of our study did display similarities to the Fortenbaugh et al. (2010) data in that the catchers displayed less pelvis and trunk separation however our study displayed even lower separation degrees than the collegiate catchers. Pelvis and trunk separation was defined as the degree of motion of axial rotation. In addition, our study also displayed the rapid elbow flexion during the cocking phase. Pitchers have demonstrated approximately 100 (1.75 radians) of elbow flexion during the arm cocking phase and then the elbow must begin Kinematics and kinetics of catchers 7 extending to decrease the arm s moment of inertia which allows greater shoulder internal rotation velocity (Fleisig, Escamilla et al., 1996). The data from the current study indicate that both older and younger catchers follow a similar pattern of elbow flexion as the throwing motion progresses. Due to the nature of the catching posture, catchers typically are moving from the crouched position to a throwing position in attempt to have a quick ball release thus possibly rushing the throwing motion and abbreviating the sequentiality of the pelvis and trunk. Individual body segments function in a coordinated manner of muscle activation and movement to generate, summate, and transfer energy from the most proximal to the most distal segment (Kibler, 1998). Younger catchers had greater upper extremity segmental velocity, which is postulated to be attributed to the decrease in pelvis and trunk separation. In addition, the younger group exhibited pelvis rotation earlier in the sequence than the older catchers, which could have led not only to the decrease in pelvic-trunk separation but also the need for the upper extremity segments to create greater velocity to make up for the early rotation. Thus based on the summation of speed principle (Bunn, 1972; Putnam, 1993), pelvic rotation should precede trunk rotation. Kibler (1998) determined that a 20% decrease in energy transfer from the proximal segments, hip and trunk, to the arm necessitates an 80% increase in mass or a 34% increase in rotational velocity at the shoulder to create an equivalent resultant force at the hand. Even though the results of the present study showed significantly greater moments at the shoulder and elbow in the older catchers this was most likely due to their ability to throw harder and not segmental rotation. However, it could be questioned that if a larger sample size of younger catchers were studied, a display of greater shoulder and elbow moments may be observed due their need to increase upper extremity rotation as a result of early pelvis and trunk timing. While the segmental velocity results of the present study were not statistically significant, from a clinical perspective these results may be paramount. As older catchers grow and gain muscular strength they will also be able to throw a ball harder. It is speculated that if pathomechanics associated with a lack of proximal to distal segmental rotations continue throughout growth, the moments about the shoulder and elbow will subsequently increase. The repetitive stress applied to the weaker links of the distal kinetic chain may ultimately fail if faulty throwing mechanics are not corrected. Of interest in the catching kinematics was the degree of humeral elevation. Humeral elevation in the throwing motion of catchers has not previously

9 Downloaded by [Auburn University] at 08:09 18 February H. Plummer & G. D. Oliver been reported and we noted that younger catchers displayed greater humeral elevation than the older catchers. It could be speculated that the greater degree of elbow flexion in the older group, where they were attempting to bring the wrist close to the ear to make the abbreviated throw, prevented the humeral elevation. The greater humeral elevation observed in younger catchers may be related to level of experience or level of upper extremity muscle activation. Younger catchers may have less experience of quickly throwing to second base allowing them more time to elevate their arm to a greater degree than the older more experienced catchers. Muscle activation between younger and older catchers should be examined to determine if the level of activation affects the degree of humeral elevation seen between the two groups. Differences in timing and magnitude of upper extremity muscle activation may be enhanced due to kinetic chain sequencing. Knowledge of the magnitude of shoulder and elbow moments provides a scientific method for preventative and rehabilitation programmes utilised while working with catchers. Previous research examining upper extremity electromyography during pitching helps to provide insight on dynamic stabilising muscles of the elbow. To counteract the valgus torque acting on the ulnar collateral ligament, during maximum external rotation, the flexor-pronator mass contracts to provide a varus torque and the triceps and anconeus muscles are also active (Werner, Fleisig, Dillman, & Andrews, 1993). Lyman et al. (2001) gathered injury data on 298 baseball pitchers, aged 10 14, and found that 68% of reported elbow pain occurred medially. In addition risk factors identified for elbow pain included age and weight. While this study provides valuable insight into injuries in youth pitchers it does not address the kinematics of the participants studied which would help to explain the occurrence of injuries reported. Strengthening the entire kinetic chain in addition to correcting mechanical flaws in youth throwers may limit the occurrence of chronic and acute injuries and prolong their playing career. Adolescents have a high propensity for sustaining epiphyseal plate injuries due to the weakness of the epiphyseal plate compared to the surrounding ligaments which are typically affected in skeletally mature athletes (Sabick, Kim, Torry, Keirns, & Hawkins, 2005). Proximal humeral epiphysiolysis is a specific injury often caused in part by the rotational torque applied to the proximal humeral physis during throwing (Sabick et al., 2005). Coaches as well as clinicians working with catchers should incorporate strengthening of the rotator cuff musculature in order to provide glenohumeral stabilisation during throwing. By strengthening the rotator cuff musculature in catchers the incidence of epiphyseal injury may be decreased. A limitation of the current study was the low sample size in the two groups of catchers. We were only able to recruit 38 baseball and softball catchers in the area to participate. It is harder to recruit catchers than pitchers due to the lack of catchers typically on each team. Most teams have multiple pitchers due to pitch count restrictions whereas only one or two catchers may be present on a team. We also included catchers from two different sports using male and female participants that may have had an effect on the generalisability of the results. To our knowledge this is the first study to quantify kinematics and kinetics of the throwing motion of catchers at two different age levels. Based on our results it is clear that age does play a role in the throwing mechanics observed in catchers throwing to second base. The effects of these mechanical differences on injury are not yet fully understood and longitudinal data regarding throwing mechanics and injury prevalence are needed. We hope that these data will promote more research focus on the throwing motion of catchers and assist coaches, parents, and catchers in fundamental throwing mechanics in attempt to decrease injury. Future research should continue to examine the kinematics and kinetics across ages in both baseball and softball catchers. Participants should be close in age to account for years of experience and maturation present in youth catchers. By having a sample size close in age, experience, and maturation stronger correlations between throwing kinematics and kinetics can be determined. 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