Do Pitching Biomechanics Differ Between Windup and Stretch Pitching Deliveries From a Dirt Surface Mound in College...

It is unknown how pitching biomechanics in college baseball pitchers differ between windup and stretch pitching deliveries from a dirt surface mound. The purpose was to assess differences in shoulder and elbow kinetics and pitching kinematics in college pitchers between windup and stretch pitching deliveries from a dirt surface mound. Eighteen college pitchers pitched from a dirt surface mound using windup and stretch pitching deliveries. All pitchers were tested using a 240-Hz, 12-camera motion analysis system, and 28 kinematic and 7 kinetic parameters were calculated. Paired within-subjects t tests (P < .05) were used to assess biomechanical differences between windup and stretch deliveries. Maximum shoulder horizontal adduction torque, maximum shoulder anterior force, maximum lead knee height, ball velocity at ball release, forward trunk tilt at ball release, maximum upper trunk angular velocity, maximum elbow extension angular velocity, and maximum shoulder internal rotation angular velocity were all significantly greater using a windup delivery compared with a stretch delivery. Pelvic drift at maximum lead knee height was the only parameter that was significantly greater in a stretch delivery compared with a windup delivery. Nine of the 35 (26%) biomechanical parameters were significantly different between windup and stretch deliveries. Shoulder injury risk may be slightly lower using a stretch delivery compared with a windup delivery due to overall lower shoulder kinetics during the stretch delivery.