Investigation of pitching performance and physical changes associated with fatigue

Abstract In this study, the impact of repeated pitching on the shoulder performance and physical parameters was examined in 21 male baseball players, averaging 23.1 years old. Pitching performance and physical changes were assessed across six cycles of 15 pitches with 10-minute rest intervals. The visual analogue scale was used to measure fatigue levels, while the active shoulder range of motion was also measured before and after each pitching cycle. The Rapsodo Pitching system was used to measure ball velocity, release point height, spin rate, and strike rate to evaluate pitching performance. Fatigue levels significantly increased after pitching cycle (p < 0.01), coupled with decreases in shoulder flexion on the throwing side (p = 0.02) as well as flexion and abduction on the non-throwing side (p = 0.03 and 0.02, respectively). The ball velocity decreased in the last cycle (p = 0.03), while no significant changes were observed in release point height, ball spin rate, or strike rate. Active shoulder flexion on the throwing side emerged as a more sensitive indicator of pitching-related fatigue than overall pitching form. These findings underscore the importance of post-game recovery for both the throwing and non-throwing sides to mitigate the effects of pitching fatigue on shoulder performance.