This study investigated differences in kinematic and temporal parameters between two velocity groups of baseball pitchers. Data were collected from 127 healthy college and professional baseball pitchers. Those who threw faster than 1 SD above the sample mean (>38.0 m/s) were assigned to the high velocity group (n = 29), and those who threw slower than 1 SD below the sample mean (<34.2 m/s) were assigned to the low velocity group (n = 23). Twelve kinematic parameters and 9 temporal parameters were measured and analyzed. The pattern of lead knee movement was also investigated. Maximum shoulder external rotation, forward trunk tilt at the instant of ball release, and lead knee extension angular velocity at the instant of ball release were significantly greater in the high velocity group. Maximum lead knee flexion angular velocity was significantly greater in the low velocity group. Seventy percent of the high velocity group showed knee extension during the approach to ball release, whereas the low velocity group showed a variety of knee movement patterns involving less knee extension and more knee flexion. The greater shoulder external rotation in the high velocity group produced an increased range of motion during the acceleration phase.
T. Matsuo is with the Faculty of Health & Sports Sciences at Osaka University, 1-17 Machikaneyama, Toyonaka, Osaka, 560-0043 Japan. R.F. Escamilla is with the Michael W. Krzyzewski Human Performance Laboratory in the Division of Orthopaedic Surgery at Duke University Medical Center, P.O. Box 3435, Durham, NC 27710. G.S. Fleisig, S.W. Barrentine, and J.R. Andrews are with the American Sports Medicine Institute, 1313 13th Street South, Birmingham, AL 35205.