Effects of Gluteal Fatigue on Shoulder and Scapula Kinematics Among NCAA Division I Softball Athletes

Abstract

PURPOSE: The purpose of this study was to examine the effects of gluteal fatigue on shoulder and scapula kinematics during all phases of an overhead throw among National Collegiate Athletic Association (NCAA) Division I softball players. METHODS: Ten NCAA Division I softball players (19.89 1.36 years, 172.18 8.52 cm, 74.64 9.98 kg) volunteered. Over the course of three consecutive days athletes performed 60ft (18.3m) throws before and after a gluteal fatigue intervention. Kinematic data to describe the throwing motion were collected using an electromagnetic tracking system at a frequency of 100Hz. Repeated measures ANOVA were used to identify differences pre- and post-fatigue in shoulder elevation, rotation, and plane of elevation, scapula internal/external rotation, up/down rotation, and anterior/posterior tilt at all phases of throwing (foot contact, maximum external rotation, ball release, and maximum internal rotation). RESULTS: There was evidence of gluteal fatigue affecting the throwing motion in the Event x Test interaction for scapular anterior/posterior tilt [F(3,7) = 29.35, p < .01] and scapular up/down rotation [F(3,7) = 5.54, p = .03], and the main effect of Day and Test for shoulder elevation [F(2,8) = 5.01, p = .04, F(1,9) = 21.82, p < .01]. Shoulder plane of elevation, shoulder elevation, and scapula internal/external rotation revealed no statistical significance. CONCLUSION: The overhead throwing motion places great demands on the shoulder joint. Research has shown shoulder injuries are among the most common injuries in overhead throwing athletes. Appropriate sequencing of scapular and shoulder motion reduces the risk of injury as well as improves ball velocity and accuracy.