Increases in Ball Weight and Size Decrease Elbow Varus Torque During Baseball Pitching

Abstract

Background: The rates of ulnar collateral ligament injury and surgery continue to rise in baseball. Increased ball velocity and elbow varus torque may correlate with the increased risk of injury. Hypothesis: Increased ball weight and/or size correlate with decreased elbow varus torque during pitching. Study Design: Controlled laboratory study. Methods: Motion capture data of 20 healthy professional and high-level collegiate baseball pitchers pitching fastballs with 4 types of baseballs were collected. The baseballs were 5 oz (standard weight) or 6 oz, with a circumference of 9 inches (standard size) or 5% larger. Five kinetic parameters, 25 kinematic parameters, and 7 ball movement parameters were calculated. Differences for each parameter were compared using 2-factor (ball weight × size) repeated-measures analysis of variance (P