Alterations in Upper Extremity Motion after Scapular-Muscle Fatigue

Abstract

Objective: To determine the effect of scapular fatigue on shoulder and elbow kinematics and accuracy. Design: Pretest–posttest. Setting: Laboratory. Participants: 30 healthy men. Interventions: Subjects performed seated overhead throws into a target before and after a standardized scapular-muscle-fatigue protocol. Main Outcome Measurements: Shoulder and elbow kinematic data were analyzed during throwing. Scapular upward rotation was measured (0°, 45°, and 90° humeral elevation in scaption) with an inclinometer. Throwing accuracy was measured as mean error distance from the target (cm). Results: After fatigue, there was a significant increase in total elbow motion (12 % more in cocking phase, P < .05) and elbow velocity in the follow-through phase (average and maximum into flexion, P < .05). Throwing accuracy decreased 26% after fatigue ( P < .05). Conclusions: Scapular-muscle fatigue results in compensatory motions at the elbow that might affect performance and contribute to elbow pathologies.