Shoulder muscle onset timing during clinical assessment movements is the same in elite handball players as non-athletes: Implications for clinical assessment

Abstract

Objectives: This study examines neuromuscular firing patterns in overhead athletes and non-athletes of the periscapular, prime-moving, and rotator cuff muscles during “clinical” cardinal plane physiological movements. Design: Cohort prospective study. Setting: EMG recordings were taken of the periscapular, prime-moving, and rotator cuff muscles during flexion, scaption, and abduction performed at fast, medium, and slow speeds with a loaded (3 kg) and unloaded arm. Participants: 14 Handball players and 20 non-athletes. Differences in firing patterns between groups were analyzed by fitting mixed linear models with random intercepts per subject, and fixed factors for group, muscle, movement type, speed, and load. Main outcome measures. No difference in timing of activation was seen between the professional athletes and non-athletes. Results: Speed and load appear to independently vary muscle activation timing in a non-intuitive manner in both athletes and non-athletes. Onset timing of periscapular, prime movers and rotator cuff muscles are prior to movement in all scenarios studied, with rotator cuff muscles firing last. Conclusions: Onset activation patterns in overhead athletes are not different to non-athletes during cardinal plane movements.