Reliability of Shoulder Movement Kinematics in Healthy Young Adults

Abstract

Shoulder biomechanics research is crucial for understanding mobility and managing injuries but lacks consistency in methodology and findings when compared to studies focusing on the lower limbs. This study aimed to evaluate the reliability of a shoulder biomechanical protocol in healthy, young individuals to enhance the understanding of shoulder function and contribute to standardization. Thirteen participants completed five standardized shoulder function tasks across two sessions separated by up to two weeks. Tasks included elevation (maximum abduction, flexion, comb through hair) and non-elevation (tie apron, floor to shoulder lift). Motion capture assessed three-dimensional scapulothoracic (ST) and glenohumeral (GH) kinematics. Reliability of kinematic variables was evaluated using the Intraclass Correlation Coefficient (ICC). Non-elevation tasks showed better reliability, with 61.1% of variables rated good to excellent, compared to 31.5% for elevation tasks, which also had greater variability. While the protocol reliably assesses some tasks, further investigation is needed to standardize elevation-based tasks.