The effects of wrist height at lead foot contact on shoulder and elbow joint moments in baseball pitching.

Abstract

The effects of arm position at lead foot contact (FC) on shoulder and elbow joint kinetics are not well understood. This study investigated the effects of wrist height relative to the shoulder at FC on the joint moments and pitching kinematics in high school and collegiate pitchers using a motion capture system. Peak elbow varus and shoulder internal rotation moments, along with upper extremity, pelvis, and upper torso kinematics, were compared among pitchers with the wrist positioned below, at, or above the shoulder at FC. Compared with pitchers whose wrist remained below the shoulder, those with the wrist above the shoulder demonstrated greater elbow varus and shoulder internal rotation moments, greater shoulder external rotation and upper torso rotation throughout most of the arm-cocking phase, a shorter arm-cocking phase, and earlier timing of key pitching events. Delaying the throwing arm motion during the stride by having a wrist below the shoulder at FC may help elongate the arm-cocking phase and minimize joint moments. Wrist height at lead foot contact may provide a simple and practical method for identifying pitchers who may be experiencing elevated joint loading. The findings also support the concept that pitching mechanics at lead foot contact influence kinematics throughout the subsequent phases of the pitching motion.