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Background It has long been thought by many baseball coaches and players that throwing the fastball from the stretch is more stressful to the shoulder and elbow than throwing the fastball from the wind-up. However, no research has compared the biomechanics of these 2 pitch variations. Hypothesis There are differences in shoulder and elbow kinetics, kinematic position at front-foot contact, timing, and ball velocity between the 2 pitching variations. Study Design Controlled laboratory study. Methods Twenty-eight professional baseball pitchers (aged 22.1 ± 2.8 years) pitched fastballs from both the wind-up and stretch positions in an indoor laboratory setting. Three-dimensional motion-analysis systems were employed to capture the pitching motion. Kinetic variables, kinematic variables at lead-foot contact, and temporal variables of the 2 pitching variations were compared. Results There was no significant difference between the 2 pitch variations for the kinetic, kinematic, or temporal variables. The difference between the ball velocities was statistically significant, but the mean difference was only 0.2 m/s. Conclusions The pitching biomechanics between the wind-up and stretch fastball showed no statistical differences in joint kinetics, kinematics, or timing, and clinically insignificant differences in ball velocity. Clinical Relevance The current results suggest that pitching the fastball from the stretch is not necessarily more stressful to the shoulder and elbow.

Joint range of motion and physical capacities have been shown to change with age in both throwing athletes and non-athletes. The age of professional baseball pitchers could span from late teens to mid-40s. However, the effects of age on the pitching kinematics among professional baseball pitchers are still unknown. In this study, 67 healthy professional baseball pitchers were tested using a 3D motion analysis system. Their mean age was 23.7+/-3.3 years (range 18.8-34.4). The 12 pitchers more than one standard deviation older than the mean (i.e., older than 27.0 years) were categorized into the older group, and the 10 pitchers more than one standard deviation younger than the mean (i.e., younger than 20.4 years) were defined as the younger group. In all, 18 kinematic variables (14 position and 4 velocity) were calculated, and Student's t-tests were used to compare the variables between the two groups. Six position variables were found to be significantly different between the two groups. At the instant of lead foot contact, the older group had a shorter stride, a more closed pelvis orientation, and a more closed upper trunk orientation. The older group also produced less shoulder external rotation during the arm cocking phase, more lead knee flexion at ball release, and less forward trunk tilt at ball release. Ball velocity and body segment velocity variables showed no significant differences between the two groups. Thus, differences in specific pitching kinematic variables among professional baseball pitchers of different age groups were not associated with significant differences in ball velocities between groups. The current results suggest that both biological changes and technique adaptations occur during the career of a professional baseball pitcher.

Summary: Injuries to the elbow joint are becoming more and more prominent in today’s sporting society. This is largely because of the biomechanical demands during popular sports such as baseball, softball, and tennis; wherein the majority of elbow injuries occur. Implications for injuries in these sports range from overuse to incorrect mechanics, which cause increased loads at the elbow joint. This can be seen in the overhead throwing motion where a large varus torque leads to tensile injuries in the medial elbow and compressive injuries in the lateral elbow. The tennis serve produces large varus torque like in baseball pitching, but significantly less elbow extension velocity and elbow flexion torque. In cricket, elbow biomechanics play a very important role, as the rules prohibit elbow flexion during the arm acceleration of bowling. Windmill softball pitchers were once thought to not be at high risk for injury because of their style of throw. However, studies of windmill pitching reveal rapid kinematics and high kinetic loads that are leading to increased amounts of injuries. To improve on surgical treatment, physical therapy, and even prevention of elbow injuries, one must have a good understanding of the biomechanics of the elbow during these activities. This article presents recent advances in understanding elbow biomechanics during sports, based on studies published since the year 2000.

Because youth athletes are smaller and weaker than their adult counterparts, smaller equipment and fields are often used in youth sports. Previous research has shown that youth baseball pitchers use similar motions to older pitchers, but generate lower kinetics and angular velocities at the shoulder and elbow. The purpose of this study was to determine potential biomechanical benefits for youth pitchers to use lighter baseballs. Thirty-four youth (11.1 ± 0.7 years) pitchers pitched both standard [5 ounce (142 g)] and lightweight [4 ounce(113 g)] baseballs in a laboratory setting. Kinematic and kinetic parameters were measured with a six-camera high-speed motion analysis system. Three repeated measures MANOVAs were used to compare (p > 0.05) position, velocity, and kinetic parameters between the standard and lightweight baseballs. Subjective data were also collected. Pitching the lightweight ball produced no difference in arm position, but greater shoulder, elbow, and ball velocities. With the lightweight ball, pitchers produced decreased kinetics.Post-hoc analysis of the kinetic data revealed significant decreases in elbow varus torque and shoulder internal rotation torque. The data suggest that playing with lightweight baseballs may reduce the risk of overuse injury in the youth pitcher and also help develop arm speed. However, before introducing lightweight baseballs into the youth game, the effect of lighter, faster pitched balls for the batters and fielders should also be considered.

BackgroundThere is little evidence supporting current safety recommendations for adolescent pitchers.HypothesisPitching practices of adolescent pitchers without history of arm injury will be significantly different from those of adolescent pitchers who required shoulder or elbow surgery.Study DesignCase control study; Level of evidence, 3.MethodsNinety-five adolescent pitchers who had shoulder or elbow surgery and 45 adolescent pitchers who never had a significant pitching-related injury completed a survey. Responses were compared between the 2 groups using t tests and analyses. Multivariable logistic regression models were developed to identify the risk factors.ResultsThe injured group pitched significantly more months per year, games per year, innings per game, pitches per game, pitches per year, and warm-up pitches before a game. These pitchers were more frequently starting pitchers, pitched in more showcases, pitched with higher velocity, and pitched more often with arm pain and fatigue. They also used anti-inflammatory drugs and ice more frequently to prevent an injury. Although the groups were age matched, the injured group was taller and heavier. There were no significant differences regarding private pitching instruction, coach's chief concern, pitcher's self-rating, exercise programs, stretching practices, relieving frequency, pitch type frequency, or age at which pitch types were first thrown.ConclusionPitching practices were significantly different between the groups. The factors with the strongest associations with injury were overuse and fatigue. High pitch velocity and participation in showcases were also associated with increased risk for injury.Clinical RelevanceNew recommendations were made based on these results. Adherence to the recommendations may reduce the incidence of significant injury to adolescent pitchers.

Background: The risk of elbow or shoulder injury for young baseball pitchers is unknown. Purpose/Hypothesis: The purpose of this study was to quantify the cumulative incidence of throwing injuries in young baseball pitchers who were followed for 10 years. Three hypotheses were tested: Increased amount of pitching, throwing curveballs at a young age, and concomitantly playing catcher increase a young pitcher’s risk of injury. Study Design: Cohort study; Level of evidence, 3. Methods: In sum, 481 youth pitchers (aged 9 to 14 years) were enrolled in a 10-year follow-up study. Participants were interviewed annually. Injury was defined as elbow surgery, shoulder surgery, or retirement due to throwing injury. Fisher exact test compared the risk of injury between participants who pitched at least 4 years during the study and those who pitched less. Fisher exact tests were used to investigate risks of injury for pitching more than 100 innings in at least 1 calendar year, starting curveballs before age 13 years, and playing catcher for at least 3 years. Results: The cumulative incidence of injury was 5.0%. Participants who pitched more than 100 innings in a year were 3.5 times more likely to be injured (95% confidence interval = 1.16 to 10.44). Pitchers who concomitantly played catcher seemed to be injured more frequently, but this trend was not significant with the study sample size. Conclusion: Pitching more than 100 innings in a year significantly increases risk of injury. Playing catcher appears to increase a pitcher’s risk of injury, although this trend is not significant. The study was unable to demonstrate that curveballs before age 13 years increase risk of injury. Clinical Relevance: The risk of a youth pitcher sustaining a serious throwing injury within 10 years is 5%. Limiting the number of innings pitched per year may reduce the risk of injury. Young baseball pitchers are encouraged to play other positions as well but might avoid playing catcher.

BackgroundThe curveball has been anecdotally considered as a dangerous pitch among youth pitchers, especially for their ulnar collateral ligaments. No biomechanical studies have been conducted among youth pitchers comparing different types of pitches.HypothesisThe kinetics of the baseball throw varies significantly between the fastball, curveball, and change-up for youth pitchers. Kinematic and temporal differences are also expected.Study DesignControlled laboratory study.MethodsTwenty-nine youth baseball pitchers (age, 12.5 ± 1.7 years) pitched 5 fastballs, 5 curveballs, and 5 change-ups with maximum effort in an indoor laboratory setting. Data were collected with a 3-dimensional motion analysis system. Kinetic, kinematic, and temporal parameters were compared among the 3 pitches.ResultsFor elbow varus torque, shoulder internal rotation torque, elbow proximal force, and shoulder proximal force, the fastball produced the greatest values, followed by the curveball and then the change-up. The fastball also produced the greatest elbow flexion torque. Shoulder horizontal adduction torque and shoulder adduction torque were the least for the change-up. Several differences in body segment position, velocity, and timing were also found.ConclusionsIn general, elbow and shoulder loads were the greatest in the fastball and least in the change-up. Kinematic and temporal differences were also found among the 3 pitch types.Clinical RelevanceThe curveball may not be more potentially harmful than the fastball for youth pitchers. This finding is consistent with recent epidemiologic research indicating that amount of pitching is a stronger risk factor than type of pitches thrown.

Background Controversy exists about whether breaking pitches are more stressful than are fastballs. Previous biomechanical studies compared kinematics but not kinetics. Hypothesis Elbow and shoulder forces and torques are statistically different among the fastball, curveball, change-up, and slider. Study Design Descriptive laboratory study. Methods Twenty-one healthy collegiate pitchers were studied with a high-speed automated digitizing system. All subjects threw fastballs (n = 21), most threw curveballs (n = 20) and change-ups (n = 19), and a few threw sliders (n = 6). Wrist, elbow, and shoulder kinetics were calculated using inverse dynamics. Nine kinetic and 26 kinematic parameters were compared among the different pitch types using repeated-measures analysis of variance. Results At the shoulder, internal rotation torque, horizontal adduction torque, abduction torque, and proximal force were significantly less in the change-up than in the other 3 pitches. Shoulder horizontal adduction torque was greater in the fastball than in the curveball and slider. Shoulder proximal force was greater in the slider than in the curveball. Elbow proximal force was less in the change-up than in the other 3 pitches. Elbow varus torque was greater in the fastball and curveball than in the changeup. Elbow flexion torque was greater in the curveball than in the change-up. The curveball and change-up demonstrated kinematic differences from the fastball, consistent with previous studies. Conclusion There were significant kinematic differences between the fastball and curveball but few kinetic differences. The change-up had lower joint kinetics, lower angular velocities, and different body positions than the other 3 pitch types had. Results for the slider were inconclusive because of small sample size. Clinical Relevance Because the resultant joint loads were similar between the fastball and curveball, this study did not indicate that either pitch was more stressful or potentially dangerous for a collegiate pitcher. The low kinetics in the change-up implies that it is the safest.

In throwing activities, the elbow is sometimes stressed to its biomechanical limits. In this article, forces, torques, angular velocities, and muscle activity about the elbow are reviewed for the baseball pitch, the football pass, the javelin throw, the windmill softball pitch, the tennis serve, and the golf swing. The elbow goes through rapid extension in baseball pitching (about 2400 degrees/s) and rapid flexion in the javelin throw (about 1900 degrees/s). During baseball pitching, the elbow joint is subject to a valgus torque reaching 64 Nm, and requires proximal forces as high as 1000 N to prevent elbow distraction. The ulnar collateral ligament (UCL) rupture in baseball pitching, lateral epicondylitis in the tennis backhand, and other injury mechanisms are also discussed.