Results: Paired t tests showed significantly lower peak force during isokinetic protraction at high velocity (p,0.05), a significantly lower protraction/retraction ratio (p,0.01), and significantly lower electromyographic activity in the lower trapezius muscle during isokinetic retraction on the injured side than on the non-injured side (p,0.05).
Conclusion: These results confirm that patients with impingement symptoms show abnormal muscle performance at the scapulothoracic joint.