Comparison of Biomechanical Variables and Pitching Timing in Professional Baseball Pitchers According to Ball Velocity.

This study aimed to identify key kinematic and kinetic factors that affect ball velocity in professional baseball pitchers, focusing on the role of pitching timing. It was hypothesized that pitchers in the high-velocity group (HG) would exhibit delayed timing of key pitching events, as well as greater pelvic and trunk kinematics, and higher ground reaction force (GRF) than those in the low-velocity group (LG). Based on ball velocity, this study categorized 40 professional pitchers registered with the Korea Baseball Organization into HG and LG. A Vicon motion capture system, force plates, and a speed gun were utilized to collect data on body segment motion, joint angular velocity, and GRF. Independent t-tests were conducted to compare differences between the 2 groups. The results revealed that the HG exhibited notably higher trunk angular velocity, drive leg anterior GRF impulse, and stride leg vertical GRF than the LG. Moreover, the HG demonstrated later stride foot contact, maximal external rotation, and ball release, indicating that delayed pitching timing contributes to increased ball velocity. These results highlight the importance of trunk rotation and GRF production for achieving high ball velocity. Furthermore, the timing of key pitching events is considered a distinguishing factor among elite pitchers.