Vascular Problems in Elite Throwing Athletes.

There are approximately 880 and 3,600 major league baseball and minor league baseball players who currently are active in their respective leagues, with thousands of players in the collegiate, high school, and little league ranks. Although relatively uncommon, vascular injuries, such as thoracic outlet syndrome, axillary artery compression, quadrilateral space syndrome, and direct vascular trauma, can afflict these players. These career- and limb-threatening injuries can mimic often seen muscular sprains and strains in their early stages with nonspecific symptoms, such as exertional fatigue, which can delay diagnosis with disastrous sequelae, including thrombus propagation, aneurysm rupture, and ischemia from distal embolization. The goal of this review is to discuss the pathophysiology, diagnosis, and treatment of these injuries to increase awareness of sport-related vascular phenomena among the hand and upper-extremity surgery community because these players typically are seen first in the training room or a hand specialist's office.

Glenohumeral Instability and Arm Pain in Overhead Throwing Athletes: A Correlational Study.

Background: The overhead activity of throwing a baseball is arguably the most demanding athletic endeavor placed on the glenohumeral (GH) joint. Previous studies illustrate that 75-80% of baseball players will experience some degree of upper extremity (UE) pain. GH instability is thought to play a role. Purpose: The purpose of this study was to investigate the relationship between GH joint hypermobility and instability with measures of arm pain and performance in overhead throwing athletes. Methods: Actively competing baseball pitchers were recruited and evaluated once with the anterior-posterior Load and Shift examination procedure, the Kerlan-Jobe Orthopedic Clinic Shoulder and Elbow Questionnaire (KJOC), and the Functional Arm Scale for Throwers (FAST). Multivariate analysis was performed to identify correlation between severe GH capsular laxity (GH instability), mild capsular laxity (GH hypermobility), no capsular laxity (GH normal), and presence of shoulder pain when pitching. Study Design: Cross-sectional Study. Results: Forty-five pitchers were evaluated, 62.2% of throwing shoulders were classified normal stability, 26.7% were classified hypermobile, and 11.1% were classified unstable. Average KJOC scores for pitchers with the three mobility categories were 66.1 (normal), 59.7 (hypermobile), and 45.0 (unstable). Average FAST scores among the pitchers were 19.9 (normal), 34.2 (hypermobile), and 32.2 (unstable). Pitchers with GH instability and GH hypermobility demonstrated increased arm pain compared to athletes with normal GH joints; KJOC scores of 3.2, 5.5, and 7.4 (p = 0.0007), respectively. Conclusion: Pitchers with GH instability and hypermobility demonstrated significantly increased ratings of arm pain compared to pitchers with no capsular laxity. Level of Evidence: 3b.

Can the Scapular Dyskinesis Test be Associated with Throwing Related Injuries During the Course of Collegiate Baseball Seasons?

Background: A pattern of scapular dyskinesis on the dominant side has been demonstrated to be associated with a decrease in throwing arm conditions identified by a self-report outcome assessment in collegiate baseball pitchers during the course of a single season. However, it is unclear if symptomatic shoulders in baseball pitchers may be associated with the presence of scapular dyskinesis. Purpose: To study the relationship between the presence of scapular dyskinesis and throwing-related injury in collegiate baseball pitchers during each respective course of up to four subsequent seasons. Methods: A single Division 1 National Collegiate Athletic Association team participated in this study over a four-year-period. The scapular dyskinesis test was implemented during the preseason for baseball pitchers. Players were followed throughout each respective season to track the incidence of throwing-related upper extremity injuries. Results: A total of 36 collegiate baseball pitchers (height: 185.3 ± 5.6 cm, weight: 88.8 ± 7.8 kg, age: 20.0 ± 1.5 years) consisting of 57 pitcher seasons were followed in this study, in which 18 pitchers remained with the team for more than one year. Twenty-seven of the 57 pitchers were classified as having scapular dyskinesis demonstrated at around 90° of shoulder flexion on the throwing side. Five injuries (13.2% of a total of 38 injuries) were diagnosed as throwing-related shoulder injuries during the course of the intercollegiate baseball seasons. Four of the five throwing-related shoulder injuries occurred in pitchers who had scapular dyskinesis on their dominant side. Consequently, the odds ratio was 5.04 for the collegiate pitchers with scapular dyskinesis on the throwing arm side associated with a throwing-related shoulder injury compared to those with no scapular dyskinesis (p = 0.16). No relationship was identified between scapular dyskinesis on the throwing arm side and throwing-related elbow injury. Eighty-one percent of the scapular dyskinesis test results were not changed on the throwing side from the previous to the following year for those 18 pitchers who were followed for more than one season, whereas 42.9% of the results remained unchanged on the non-throwing side. Conclusion: The results suggest that collegiate baseball pitchers with dominant arm scapular dyskinesis likely are at increased risk of throwing-related shoulder injury. Level of evidence: Level 2, Prospective Cohort Study.

Four-year trend in shoulder and elbow injuries in competitive-level high school baseball pitchers: a repeated cross-sectional survey.

BACKGROUND: Shoulder and elbow injuries are the main cause of throwing disability among high school baseball pitchers. However, longitudinal studies on shoulder and elbow injuries among competitive-level high school baseball pitchers have been insufficient. This study aimed to investigate shoulder and elbow injuries in competitive-level high school baseball pitchers over a four-year period and elucidate the effects of implementing medical checkups on the incidence of shoulder and elbow injuries. METHODS: Five hundred fifty-two high school baseball pitchers, who received preseason medical checkups from February 2012 to February 2015, were enrolled in this study. Shoulder and elbow injuries occurring during the season after medical checkups were prospectively evaluated by a postseason questionnaire. Pitchers who were not able to pitch for >7 days owing to shoulder or elbow pain were defined as having shoulder and elbow injuries during the season. The incidence rates of shoulder and elbow injuries during the seasons were calculated and compared over the 4-year period. RESULTS: Ninety-six percent of medical checkup participants were included in the study. The mean questionnaire collection rate of the prospective study was 71.6% (range: 67.7-78.9%). The incidence of shoulder and elbow injuries significantly decreased from 20.0% in 2012 to 7.7% in 2015 (P = .013). CONCLUSION: The four-year trend in the incidence of shoulder and elbow injuries in competitive-level high school baseball pitchers was evaluated. The incidence of shoulder and elbow injuries during the season significantly decreased with a linear downward trend during the survey period after the implementation of medical checkups.

Relación entre variables psicológicas y lesiones deportivas en lanzadores de béisbol / Relação entre habilidades psicológicas e lesões desportivas em lançadores de beisebol / Relationship between psychological variables and sports injuries in baseball pitchers

RESUMEN Se realizó un estudio transversal, descriptivo y correlacional para determinar la relación entre variables psicológicas y lesiones en 34 lanzadores de béisbol de diferentes niveles competitivos. Se describieron las lesiones mediante análisis de frecuencias y distribución porcentual, así como media, desviación típica, asimetría y curtosis para las variables psicológicas; se realizó además la prueba de normalidad mediante K-S para una muestra. Se compararon las variables psicológicas entre grupos de lanzadores mediante Anova de un factor y se analizó la relación entre ambos grupos de variables mediante el coeficiente de correlación de Pearson. Se compararon las variables psicológicas en relación a las lesiones, empleando la prueba t para muestras independientes y Anova de un factor en cada caso, con un intervalo de confianza del 95 % donde p≤0.05. Fueron empleados el cuestionario de aspectos deportivos y lesiones, inventario de ansiedad rasgo-estado, inventario de ansiedad estado en competencia e inventario psicológico de ejecución deportiva. Se obtuvo una marcada presencia de lesiones y un perfil psicológico donde la ansiedad-rasgo, el control de la atención, la autoconfianza, el nivel motivacional y el control de afrontamiento positivo constituyen los puntos fuertes, existiendo diferencias en la ansiedad, según el nivel competitivo. Excepto el control de la actitud, las habilidades psicológicas mostraron relación con las lesiones. Los lanzadores con mayor cantidad y gravedad de lesiones durante las competencias presentan mayor ansiedad. Se concluye afirmando que la preparación psicológica del lanzador de béisbol debe poseer la finalidad de optimizar su rendimiento deportivo y preservar su estado de salud.

RESUMO Foi realizado um estudo transversal, descritivo e correlacional para determinar a relação entre variáveis psicológicas e lesões em 34 lançadores de beisebol de diferentes níveis competitivos. As lesões foram descritas por análise de frequência e distribuição percentual, assim como média, desvio padrão, enviesamento e curtose para as variáveis psicológicas; o teste de normalidade K-S também foi realizado para a amostra. As variáveis psicológicas foram comparadas entre grupos de pitchers através de um fator único. Anova e a relação entre ambos os grupos de variáveis foi analisada por meio do coeficiente de correlação de Pearson. As variáveis psicológicas foram comparadas em relação às lesões, utilizando o teste t para amostras independentes e um fator Anova em cada caso, com um intervalo de confiança de 95 %, em que p≤0.05. Foi utilizado o questionário de aspectos e lesões desportivas, inventário de ansiedade do estado do traço, inventário de ansiedade do estado na competição e inventário psicológico do desempenho desportivo; uma presença marcada de lesões e um perfil psicológico onde a ansiedade do traço, o controlo da atenção, a autoconfiança, o nível motivacional e o controlo positivo da resposta constituem os pontos fortes obtidos, com diferenças na ansiedade, de acordo com o nível competitivo. Com restrição do controlo de atitude, as capacidades psicológicas mostraram relação com lesões. Os lançadores com maior quantidade e gravidade de lesões durante as competições apresentam maior ansiedade. Conclui-se que a preparação psicológica do lançador de beisebol deve ter o propósito de otimizar o seu desempenho desportivo e preservar a sua saúde.

ABSTRACT A cross-sectional, descriptive and correlational study was carried out to determine the relationship between psychological variables and injuries in 34 baseball pitchers of different competitive levels. Injuries were described by frequency analysis and percentage distribution, as well as mean, standard deviation, asymmetry and kurtosis for psychological variables; the K-S normality test was also performed for the sample. The psychological variables were compared between groups of pitchers by means of a one-factor Anova and the relationship between both groups of variables was analyzed by means of Pearson's correlation coefficient. Psychological variables were compared in relation to injuries, using the t-test for independent samples and one-factor Anova in each case, with a confidence interval of 95 % where p≤0.05. The questionnaire of sports aspects and injuries, trait-state anxiety inventory, state anxiety inventory in competition and psychological inventory of sports performance were used; a marked presence of injuries and a psychological profile where trait-anxiety, attention control, self-confidence, motivational level and positive coping control constitute the strong points were obtained, with differences in anxiety, according to the competitive level. Except for attitude control, psychological skills showed a relationship with injuries. The throwers with greater number and severity of injuries during the competitions present greater anxiety. It is concluded by affirming that the psychological preparation of the baseball pitcher should have the purpose of optimizing his sports performance and preserving his state of health.

Risk factors for throwing elbow injuries during pitching analyzed by simulation using human musculoskeletal model in youth baseball pitchers.

BACKGROUND: Pitching mechanics are believed to be risk factors for throwing elbow injury. Thus, a prospective study of abnormal mechanics in youth baseball players is needed. This study aimed to analyze the ulnar collateral ligament during normal pitching using SIMM (Software for Interactive Musculoskeletal Modeling) for analysis and investigate the risk parameters of throwing elbow injuries in youth baseball players. We hypothesized that excessive ulnar collateral ligament force during pitching would be a risk factor for throwing elbow injuries in this population. METHODS: In this cohort study, youth baseball pitchers (aged 9-11 years) were instructed to throw a ball into a netted target. Using a SIMM musculoskeletal model, we analyzed the force of the anterior band of the anterior oblique ligament, posterior band of the anterior oblique ligament (AOL_PB), and elbow varus moment during pitching (foot contact to ball release). We calculated the integral of each force of the anterior band of the anterior oblique ligament and AOL_PB during pitching and summarized these data to establish an impulse at the medial epicondyle. Each participant was followed up for 12 months to assess the occurrence of throwing elbow injury. RESULTS: During the 12-month follow-up period, 18 pitchers (28.1%) reported throwing elbow injuries in the throwing arm. The results of this study showed that the maximum AOL_PB force and the impulse at the medial epicondyle were risk factors for throwing elbow injuries. The maximum AOL_PB force was significantly higher in the throwing elbow injury group than in the uninjured group (59.4 ± 17.8 N vs. 47.1 ± 17.5 N, P = .014). The impulse at the medial epicondyle was also significantly different (11.1 ± 4.0 N ï½¥ s in the throwing elbow injury group vs. 8.3 ± 4.4 N ï½¥ s in the uninjured group, P = .025). CONCLUSIONS: Increasing the AOL_PB force or the impulse at the medial epicondyle may increase the risk of throwing elbow injuries in youth baseball pitchers. It may be possible to reduce injury risk by focusing on ways to decrease AOL_PB load and cumulative stress on the medial epicondyle throughout the throwing motion while still maintaining high levels of ball velocity.

Efecto de las lesiones deportivas sobre variables psicológicas en lanzadores de béisbol / Effect of sports injuries on psychological variables in pitchers of baseball

Resumen La presente investigación se enmarca en el campo de las lesiones deportivas, teniendo como objeto de estudio su relación con las variables psicológicas, asociadas a la ejecución deportiva en lanzadores de béisbol. Se trabajó con 24 lanzadores lo que constituye una población heterogénea en cuanto a edad cronológica, edad deportiva, antecedentes y cantidad de lesiones sufridas. Para su evaluación, se utilizaron los siguientes instrumentos: cuestionario sobre aspectos deportivos y lesiones, el inventario del estado de ansiedad en competición y el inventario psicológico de ejecución deportiva. Los resultados obtenidos indican diferencias estadísticamente significativas en el estado de las variables psicológicas entre lanzadores con historial de lesiones y aquellos que no las presentaron en el momento del estudio, lo cual permitió determinar el efecto negativo de las lesiones sobre la autoconfianza, la ansiedad competitiva, el control del afrontamiento negativo, el control de la atención y el control visuoimaginativo. En el grupo de lanzadores con antecedentes de lesiones, se mostraron relaciones estadísticamente significativas en la autoconfianza y el control del afrontamiento negativo, estableciendo relaciones con la cantidad de lesiones sufridas, de manera tal, que, a mayor número de lesiones, mayor es la diferencia en ambas variables. Por otra parte, la motivación, el control de la actitud y el control del afrontamiento positivo no ofrecieron diferencias algunas entre lanzadores que se han lesionado y los que no lo han hecho. El efecto negativo de las lesiones sobre las variables psicológicas estudiadas mostró diferentes niveles de relación y dependencia en estos deportistas estudiados.

Abstract The present research is framed in the field of sports injuries, having as object of study its relation with the psychological variables associated to the sports performance in baseball pitchers. The work was developed with 24 pitchers constituting a heterogeneous population in terms of chronological age, sports age, history and number of injuries suffered. The following instruments were used for its evaluation: Questionnaire on Sports Aspects and Injuries, the Inventory of the State of Anxiety in Competition and the Psychological Inventory of Sports Execution. The results obtained indicate statistically significant differences in the state of the psychological variables between pitchers with a history of injuries and those who did not at the time of the study, which allowed determining the negative effect of the injuries on self-confidence, competitive anxiety, negative coping control, attention control and imaginative visual control. In the group of pitchers with a history of injuries, statistically significant relationships were shown in self-confidence and negative coping control, establishing relationships with the number of injuries suffered in such a way that the greater the number of injuries, the greater the difference in both variables. On the other hand, motivation, attitude control and positive coping control did not offer any differences between injured and uninjured pitchers. The negative effect of the injuries on the psychological variables studied showed different levels of relationship and dependence in these athletes studied.

Kerlan-Jobe Orthopaedic Clinic (KJOC) score and scapular dyskinesis test in collegiate baseball players.

BACKGROUND: The Kerlan-Jobe Orthopaedic Clinic (KJOC) score has been used to describe various parameters of throwing shoulder and elbow function for the return to play after a long period of rehabilitation, such as after ulnar collateral ligament reconstruction. No study has yet to identify how scapular dyskinesis (SD) in baseball players affects the KJOC score. This study investigated the relationship of the KJOC score to SD evaluated in collegiate baseball players with and without upper extremity injury. MATERIALS AND METHODS: The study participants were 30 male collegiate baseball players (13 pitchers) belonging to the National Collegiate Athletic Association D-I conference. Participants were assessed with the KJOC instrument in the beginning (PRE) and end (POST) of the season. The SD test was conducted (PRE) in shoulder flexion to identify SD RESULTS: The mean value of KJOC score was significantly less in POST than that of PRE for the pitchers with SD (89.3 and 60.5, respectively; P = .001), whereas no difference was found in the KJOC score between PRE and POST for the pitchers without SD. For the position players, no difference in the mean value of KJOC score was found between PRE and POST, regardless of SD. CONCLUSION: The results of this study provide evidence that collegiate baseball pitchers with mild SD may have lower KJOC scores, particularly setup or relief pitchers.

Biomechanical Comparisons Among Fastball, Slider, Curveball, and Changeup Pitch Types and Between Balls and Strikes in Professional Baseball Pitchers.

BACKGROUND: In professional baseball pitchers, pitching biomechanics have not been examined for the slider, and the only known study for the curveball and changeup examined limited kinetics. Moreover, no known studies have investigated pitching biomechanics between strikes and balls. Purpose/Hypothesis: The purpose was to compare pitching biomechanics in professional baseball pitchers among the fastball, slider, curveball, and changeup and between balls and strikes. It was hypothesized that pitching kinematics and kinetics would be similar among the slider, fastball, and curveball; shoulder and elbow forces and torques would be significantly lower in the changeup; and pitching biomechanics would be similar between balls and strikes. STUDY DESIGN: Controlled laboratory study. METHODS: Among 18 professional baseball pitchers, 38 reflective markers were positioned on the body and each player threw 32 to 40 maximum effort pitches-consisting of the fastball, curveball, slider, and changeup pitch types-from a regulation mound to a catcher. The markers were tracked by 18 high-speed 180-Hz cameras, and data were processed and run through a computer program to calculate 25 kinematic parameters, 7 kinetic parameters, and 4 temporal parameters for each pitch type and for both strikes and balls. A 2-way repeated-measures analysis of variance ( P < .01) was used to assess pitching biomechanical differences among pitch type and pitch result (balls vs strikes). RESULTS: During arm cocking, elbow varus torque was 8% to 9% greater in the fastball and slider compared with the changeup, shoulder horizontal adduction torque was 17% to 20% greater in the slider and curveball compared with the changeup, and shoulder anterior force was 13% greater in the curveball compared with the changeup. During arm deceleration, elbow flexor torque was 9% to 14% greater in the fastball compared with the curveball and changeup, and elbow and shoulder proximal forces were 10% to 14% greater in the fastball, slider, and curveball compared with the changeup. At ball release, forward trunk tilt was 16% to 19% greater in the fastball and curveball compared with the changeup, contralateral trunk tilt was 26% to 41% greater in the curveball compared with the slider and changeup, knee flexion was 18% greater in the changeup compared with the fastball, and the knee extended 7° more from lead foot contact to ball release in the fastball compared with the changeup. During arm cocking, pelvis angular velocity was 7% to 8% greater in the fastball compared with the curveball and changeup, and upper trunk angular velocity was 5% greater in the fastball compared with the changeup. During arm acceleration, shoulder internal rotation angular velocity was 6% to 7% greater in the fastball, slider, and curveball compared with the changeup, and ball velocity at ball release was 11% to 18% greater in the fastball compared with the slider, changeup, and curveball and 6% greater in the slider compared with the curveball. For all the kinematic, kinetic, and temporal parameters, analysis showed no significant differences between balls and strikes and no significant interactions between pitch type and pitch result. CONCLUSION: Nearly all kinetic differences among pitch types occurred between the changeup and the remaining 3 pitch types. Shoulder and elbow forces and torques and injury risk were greater among the fastball, slider, and curveball compared with the changeup but were similar among the fastball, slider, and curveball. Body segment and joint positions were similar among all pitch types at lead foot contact and at maximum shoulder external rotation; however, at ball release, throwing a fastball and curveball resulted in greater knee extension and more forward and contralateral trunk tilt compared with throwing a changeup and slider. Movement speeds for the pelvis, upper trunk, and shoulder were greatest in the fastball and least in the changeup and were generally similar among the fastball, slider, and curveball. The timing of when pelvis, upper trunk, elbow, and shoulder velocities occurred among the fastball, slider, curveball, and changeup was similar, and no kinematic or kinetic differences were noted between throwing balls and strikes. CLINICAL RELEVANCE: The results from the current study will help clinicians understand differences in pitching biomechanics in professional baseball pitchers among the fastball, slider, curveball, and changeup; the study provides limited insight into shoulder and elbow injury risk associated with different types of pitches.

Pitching form determines probabilistic structure of errors in pitch location.

According to recent motor control studies, it is important to know probabilistic structure of his/her own motor errors to choose an optimal motor plan (i.e., where you aim at) to maximise the expected gain. In this study, we questioned if pitching form determines the probabilistic structure of pitching errors in baseball pitchers. Eighteen collegiate baseball pitchers with various pitching forms including right- and left-handed overarm, sidearm and underarm throwers threw 100 pitches aiming at a target located 90 cm above the ground. Two dimensional distribution of pitch location was fitted by using bivariate normal distribution and 95% confidence ellipse was calculated. In order to quantify the pitching form, the direction of the throwing arm trajectory in frontal plane was calculated. The direction of the long axis was dependent on each participant's pitching form (e.g., right overarm pitchers pitched along a right-up-left-down ellipse and left overarm pitchers pitched along a left-up-right-down ellipse). This was confirmed by circular correlation analysis (P = 0.98). These results suggest that different mechanisms, potentially errors in pitching mechanics and errors in ball release timing, might contribute to errors along the long axis and those along the short axis.

Lower thoracic rib stress fractures in baseball pitchers.

Stress fractures of the first rib on the dominant throwing side are well-described in baseball pitchers; however, lower thoracic rib fractures are not commonly recognized. While common in other sports such as rowing, there is scant literature on these injuries in baseball. Intercostal muscle strains are commonly diagnosed in baseball pitchers and have a nearly identical presentation but also a highly variable healing time. The diagnosis of a rib stress fracture can predict a more protracted recovery. This case series presents two collegiate baseball pitchers on one team during the same season who were originally diagnosed with intercostal muscle strains, which following magnetic resonance imaging (MRI) were found to have actually sustained lower thoracic rib stress fractures. The first sustained a stress fracture of the posterior aspect of the right 8th rib on the dominant arm side, while the second presented with a left-sided 10th rib stress fracture on the nondominant arm side. In both cases, MRI was used to visualize the fractures as plain radiographs are insensitive and commonly negative early in patient presentation. Patients were treated with activity modification, and symptomatic management for 4-6 weeks with a graduated return to throwing and competition by 8-10 weeks. The repetitive high stresses incurred by pitching may cause either dominant or nondominant rib stress fractures and this should be included in the differential diagnosis of thoracic injuries in throwers. It is especially important that athletic trainers and team physicians consider this diagnosis, as rib fractures may have a protracted course and delayed return to play. Additionally, using the appropriate imaging techniques to establish an accurate diagnosis can help inform return-to-play decisions, which have important practical applications in baseball, such as roster management and eligibility.

Asymmetric Hip Rotation in Professional Baseball Pitchers.

BACKGROUND: There is a renewed interest in examining the association between hip range of motion and injury in athletes, and the data on baseball players are conflicting. Understanding whether asymmetrical hip rotation is a normal adaptation or a risk factor for injury will help therapists, trainers, and physicians develop rehabilitation programs to improve kinetic energy transfer and prevent injury. As our knowledge of hip pathology among baseball pitchers improves, establishing baselines for hip motion is critical in the further assessment of injury. HYPOTHESIS: Because of the repetitive nature of throwing sports and the adaptive changes documented in the shoulder, elite baseball pitchers would have characteristic patterns of hip internal and external rotations on their dominant throwing side (stance) and their nondominant side (stride) in extension. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Computer software was used to measure passive internal and external rotations on digital photographs of 111 professional baseball pitchers. RESULTS: In right-handed pitchers, there was significantly more internal rotation in the stance hip than the stride hip (32.2° ± 8.2° vs 30.8° ± 8.4°; P = .0349) and significantly more external rotation in the stride hip than the stance hip (36.3° ± 7.7° vs 30.8° ± 9.7°; P < .0001). While the mean difference in external rotation was 4.7°, 32% of the subjects had a >10° increase in external rotation on the stride hip relative to the stance hip. This population was statistically different from the remaining group for older age (P = .0053), lower body mass index (P = .0379), and more years in professional baseball (P = .0328). In the smaller number of left-handed pitchers, side-to-side differences in hip rotation were found but were not statistically significant. CONCLUSION: Pitchers showed more internal rotation on their stance hip and more external rotation on their stride hip. Although the mean differences are small, there is a subset of pitchers with defined characteristics in whom larger differences exist.