Impact of the Lower Body on Softball Pitching Velocity.

BACKGROUND: Pitch velocity plays a critical role in fastpitch softball success because it reduces the time a batter must react and contact the ball. Despite its importance, there is limited literature on the biomechanical contributions to pitch velocity, particularly from the lower extremities.

PURPOSE: To examine the lower extremity and pelvic kinematic, kinetic, and center of mass (COM) velocities associated with fastball pitch velocity.

METHODS: A total of 90 female high school and collegiate softball pitchers were included in the analysis. Motion capture data were collected for each participant, and the fastest 3 fastballs were averaged for analysis. Kinematics and kinetics were extracted for subsequent analysis. A Pearson correlation and a backward stepwise multiple regression were performed to identify kinematic and kinetic variables associated with, and predictive of, fastball velocity.

RESULTS: Peak vertical COM velocity (r = 0.51; P < .001) showed the strongest positive association with pitch velocity, followed by anterior COM velocity (r = 0.44; P < .001), mediolateral ground-reaction force (GRF) (r = 0.38; P < .001), and vertical GRF (r = 0.31; P = .001), while negative (clockwise) pelvic rotational velocity was inversely related (r = -0.26; P = .006). Backward stepwise regression identified COM velocities, GRFs, pelvic rotational velocity, and body mass as significant predictors, explaining 57% of the variance in pitch velocity (R 2 = 0.57; F(7, 82) = 15.51; P < .001).

CONCLUSION: These results suggest that the lower body plays a critical role in generating pitch velocity. Continued research is needed to determine how to optimize lower extremity function to enhance pitching performance while minimizing injury risk.

CLINICAL RELEVANCE: Improving fastball velocity in softball pitching depends on effective lower body and COM kinematics and kinetics. These findings support training the lower extremity to generate high force to improve pitch velocity while potentially reducing the mechanical demand placed on the upper extremity.

STUDY DESIGN: Descriptive laboratory study.