Role of Pelvis and Trunk Biomechanics in Generating Ball Velocity in Baseball Pitching.

Orishimo, KF, Kremenic, IJ, Mullaney, MJ, Fukunaga, T, Serio, N, and McHugh, MP. Role of pelvis and trunk biomechanics in generating ball velocity in baseball pitching. J Strength Cond Res 37(3): 623-628, 2023-The purpose of this study was to determine the impact of pelvis rotation velocity, trunk rotation velocity, and hip-shoulder separation on ball velocity during baseball pitching. Fastball pitching kinematics were recorded in 29 male pitchers (age 17 ± 2 years, 23 high school, 6 college). Pelvis and trunk angular velocities and hip-shoulder separation were calculated and averaged for the 3 fastest pitches. Associations between peak pelvis velocity, peak trunk velocity, hip-shoulder separation at foot contact, and ball velocity were assessed using Pearson correlation coefficients and multiple regression. The average ball velocity was 33.5 ± 2.8 m·s -1 . The average hip-shoulder separation at foot contact was 50 ± 12°. The peak pelvis velocity (596 ± 88°·s -1 ) occurred at 12 ± 11% of the time from stride foot contact to ball release, with the peak trunk velocity (959 ± 120°·s -1 ) occurring at 36 ± 11%. Peak trunk velocity was predictive of ball velocity ( p = 0.002), with 25% of the variability in ball velocity explained. No combination of factors further explained ball velocity. Hip-shoulder separation at foot contact (17%, p = 0.027), peak pelvis velocity (23%, p = 0.008), and the timing of peak pelvis velocity (16%, p = 0.031) individually predicted peak trunk velocity. The combination of peak pelvis velocity, hip-shoulder separation at foot contact, and the timing of peak trunk velocity explained 55% of the variability in trunk rotation velocity ( p < 0.001). These data highlight the importance of interactions between pelvis and trunk for maximizing velocity in pitching. Training to improve pelvis-trunk axial dissociation may increase maximal trunk rotation velocity and thereby increase ball velocity without increasing training load on the shoulder and elbow.