Abstract
BACKGROUND: There has been minimal research investigating injury and pitching performance differences between Major League Baseball (MLB) and other professional leagues. PURPOSE/HYPOTHESIS: This 2-team comparison between MLB and Japan's Nippon Professional Baseball (NPB) involved affiliated players over 5 years. We hypothesized that teams would differ in the injury incidence, mechanism of injury, pitch velocity, and pitch type usage. STUDY DESIGN: Descriptive epidemiology study. METHODS: Between 2015 and 2019, pitching data as well as injury statistics for the highest level and minor league affiliates of the Los Angeles Angels (MLB) and the Hiroshima Toyo Carp (NPB) were reviewed for significant differences in the injury prevalence, injury type, mechanism of injury, and days missed. In total, 3781 MLB and 371 NPB injuries were studied. RESULTS: MLB-affiliated players were significantly younger, taller, and heavier (P < .001) than were NPB-affiliated players. MLB-affiliated pitchers threw faster than did their NPB counterparts (P = .026). MLB minor league pitchers threw more curveballs than did NPB minor league pitchers (P = .004), and MLB minor league relief pitchers threw more sliders than did NPB minor league relief pitchers (P = .02). The MLB team had a 3.7-fold higher incidence of injuries versus the NPB team (0.030 vs 0.008 injuries per player-game, respectively) as well as more repeat injuries, with fewer days missed per injury (15.8 ± 54.7 vs 36.2 ± 55.1 days, respectively; P < .001). The MLB team also had a higher percentage of injuries that were throwing related (P < .001), were contact related (P < .001), and occurred outside of competition (P < .001) compared with the NPB team. CONCLUSION: This is the first empirical study examining injury trends and pitching characteristics between MLB and NPB athletes. MLB-affiliated pitchers threw faster and relied more on breaking pitches in comparison with NPB-affiliated pitchers. From injury data, MLB players were younger, taller, and heavier with a higher percentage of throwing-related injuries, contact injuries, and injuries sustained outside of competition. Overall, the MLB team indicated a 3.7-fold higher rate of reported injuries with fewer days missed per injury than did the NPB team. Competitive conditions are distinctly different between MLB and NPB, and thus, more extensive research collaborations in the future can identify best practices to advance health and performance for both leagues.