Pitching Kinematics and Kinetics Related to the Elbow Joint Load in Young Female Baseball Players: A Comparison With Young Male Baseball Players.

Background: Because the population of female baseball players has been increasing worldwide in recent years, it is important for female players to reduce the risk of elbow joint injuries, which occur frequently in baseball pitching. Although many biomechanical studies related to baseball pitching have clarified elbow joint loads, the participants in most of these studies were male baseball players, necessitating the expansion of investigations to female baseball players, particularly young female players.

Purpose: The objective of the present study was to elucidate the pitching mechanics related to the elbow joint load in young female players by comparing them with young male players.

Study design: Controlled laboratory study.

Methods: Overall, 295 participants, comprising 49 young female baseball players (mean age, 13.9 ± 2.0 years) and 246 young male baseball players (mean age, 14.3 ± 2.2 years), were included in the present study. Fastball pitching in the overhead style was assessed 3-dimensionally using a motion capture system and force plates. The pitching kinematics and kinetics were calculated, and sex differences were analyzed. Furthermore, multiple regression analysis evaluated the pitching kinematics and kinetics related to elbow varus moment (EVM).

Results: Stride, shoulder kinematics, EVM, ground-reaction forces, and ball velocity in the pitching of young female players were significantly lower than those in young male players. On multiple regression analysis, EVM in the pitching of young female players was associated with shoulder kinematics, and contrastingly, EVM in the pitching of young male players was related to ground-reaction force with respect to the lower body.

Conclusion: Although the pitching kinematics and kinetics in young female players were significantly lower than those in young male players, as in previous studies on adults, the pitching kinematics and kinetics that cause increases in the elbow joint load had a sex difference, and those in young female players depended on shoulder kinematics. This finding suggests that the mechanism of pitching injuries in young female players may differ from that in young male players.

Clinical relevance: Young female baseball players ought to learn proper pitching mechanics to reduce the injury risk, and the approach for learning in young female players should be different from that in young male players.