Wrist Kinematics During Pitching

Abstract

A computerized hand and wrist motion analysis system was modified to capture data at a rate of up to 1000 Hz. Using this system, wrist flexion and extension data were collected on five right-handed professional pitchers (75 pitches). A wrist position versus time graph was generated for each pitch. The pitch data produced a reproducible analysis of motion for the majority of the pitches regardless of pitcher. Based on the graphic display of data points, four phases of wrist motion during a pitch were identified. The first phase is the cocking phase, or the motion of the wrist as it moves into maximum extension. This is then followed by the most explosive phase, the acceleration phase, which represents ball propulsion. At ball release, the wrist progresses through flexion and there is a consistent decrease in wrist velocity, known as the deceleration phase. Finally, there is the recovery phase, or the return of the wrist toward neutral. Average values for wrist range of motion, length of phase, and angular velocity (degrees per second) were calculated for each phase of the pitch. This study represents a major step toward quantifying motion of the wrist during a pitch. The ability to quantify this motion may prove valuable in the assessment of throwing athletes after injury and rehabilitation.