Influence of stride length on upper extremity joint moments and ball velocity in collegiate baseball pitchers

Abstract

The initial stride down the mound is an important aspect of the baseball pitch. Understanding the implications of stride length is essential to appropriately coach baseball pitchers. The purpose of this study was to determine the association between normalised stride length and the elbow varus and glenohumeral internal rotation moments, ball velocity, trunk and pelvic rotation and forward trunk tilt. Motion analysis data collected from 99 collegiate pitchers were analysed for this study. A random intercept, mixed-effects regression model was used to determine if there were statistically significant associations between normalised stride length and the variables of interest. Secondary analyses were conducted to determine if an optimal stride length existed in this cohort. No significant associations were found between normalised stride length, ball velocity, or upper extremity joint moments. Additionally, no optimal stride length was identified; however, trends indicate that stride lengths between 131%-137% of a pitcher's leg length may be beneficial. Normalised stride length was associated with both trunk and pelvic rotation at foot contact (p < 0.001). Trunk and pelvic rotation has been previously shown to be associated with ball velocity and joint moments, indicating that stride length may have an indirect effect on ball velocity and joint moments.

Keywords: Biomechanics; mechanics; pitching.