Altered Scapulothoracic Muscle Activity in Overhead Athletes with Rotator Cuff-Related Shoulder Pain

Objective: The systematic review and meta-analysis aimed to compare the electromyographic (EMG) activity of the scapulothoracic muscles in overhead athletes with and without rotator cuff-related shoulder pain (RCRSP). Design: PubMed, Web of Science, Scopus and SPORTDiscus databases were searched from inceptions to May 2025. Methodological quality was evaluated using the Joanna Briggs Institute Appraisal Tool. Meta-analyses using random-effects models were conducted. The level of evidence was assessed using the GRADE approach. Results: Eleven studies (237 athletes with RCRSP and 205 healthy controls) were included. Very low-certainty evidence showed that athletes with RCRSP demonstrated increased upper trapezius (UT) activity (SMD=0.52; 95% CI: 0.07–0.96), decreased lower trapezius (LT) activity (SMD=−0.52; 95% CI: −0.94 to −0.11), and increased UT/LT ratios (SMD=1.20; 95% CI: −0.03–2.43) compared to healthy athletes. Delayed serratus anterior (SA) activation was also observed (SMD=1.01; 95% CI: 0.42–1.59). Conclusion: There is very low-certainty evidence that overhead athletes with RCRSP demonstrate altered scapular muscle activity. These findings may indicate an association rather than a causal relationship. Further high-quality, prospective studies are needed to confirm causal relationships and determine the clinical implications of altered scapular muscle activity in overhead athletes with RCRSP.