Abstract
Background
Rotator Cuff–Related Shoulder Pain (RCRSP) is the most common cause of shoulder pain and is associated with substantial functional limitations, reduced quality of life, and increased healthcare utilization. Although pain is the primary symptom, growing evidence suggests that shoulder muscle weakness represents a key impairment contributing to functional disability and persistent symptoms. However, the magnitude and distribution of strength deficits in individuals with RCRSP remain incompletely understood.
Objective
To systematically synthesize the available evidence regarding shoulder muscle weakness in individuals with Rotator Cuff–Related Shoulder Pain and to quantitatively estimate the extent of strength deficits compared with asymptomatic controls.
Methods
A systematic review and meta-analysis were conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020) guidelines. Electronic databases including MEDLINE (PubMed), Embase, Scopus, Web of Science, CINAHL, CENTRAL, SPORTDiscus, and PEDro were systematically searched from database inception through December 2025. Studies involving adults diagnosed with RCRSP and reporting quantitative measures of shoulder muscle strength were included. Methodological quality was assessed using the Cochrane Risk of Bias Tool Version 2 and the Newcastle–Ottawa Scale. Random-effects meta-analyses were performed, and pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated.
Results
A total of 10 studies involving 771 participants met the eligibility criteria and were included in the systematic review and meta-analysis. Individuals with RCRSP demonstrated significantly lower overall shoulder strength compared with asymptomatic controls (SMD = −0.82, 95% CI: −1.05 to −0.59, p < 0.001). Significant strength deficits were also observed in external rotation (SMD = −0.95, 95% CI: −1.24 to −0.66, p < 0.001), internal rotation (SMD = −0.71, 95% CI: −0.98 to −0.44, p < 0.001), shoulder abduction (SMD = −0.88, 95% CI: −1.17 to −0.59, p < 0.001), and shoulder flexion (SMD = −0.67, 95% CI: −0.97 to −0.37, p < 0.001). Moderate heterogeneity was observed across outcomes (I² = 41%–63%). Subgroup analyses indicated greater strength deficits among individuals with chronic symptoms and in studies utilizing isokinetic dynamometry.
Conclusion
Individuals with Rotator Cuff–Related Shoulder Pain exhibit significant reductions in shoulder muscle strength across multiple movement directions, with the largest deficits observed in external rotation and abduction. These findings suggest that shoulder weakness is a major clinical characteristic of RCRSP and should be considered a primary target of assessment and rehabilitation. Incorporating objective strength evaluation and targeted strengthening interventions may improve functional outcomes and optimize patient management