Shoulder-Focused Exercise for External-Rotator Capacity and Rotator-Cuff Strength Balance in Overhead Athletes: A Systematic Review and Meta-Analysis

Background: Shoulder-focused exercise is widely used to improve external-rotator capacity and rotator-cuff strength balance in overhead athletes, but effects may vary according to contraction mode, sport, and clinical context. Methods: PubMed, Scopus and CENTRAL were searched from inception through 15 August 2026; SPORTDiscus and ClinicalTrials.gov were additionally searched from inception through 7 October 2026. The protocol was registered in PROSPERO (CRD420261506247). Random-effects meta-analyses used restricted maximum likelihood estimation with modified Knapp–Hartung inference. Risk of bias was assessed using RoB 2 and certainty of evidence using GRADE. Results: Ten independent randomized trials contributed to the five primary meta-analyses. Isometric ER strength showed an SMD of 0.25 (95% CI −0.48 to 0.98; five trials, 240 endpoint participants; very low certainty), and concentric ER strength showed an SMD of 0.25 (95% CI −0.29 to 0.80; four trials, 138 participants; low certainty). Their approximate 95% prediction intervals were −1.53 to 2.03 and −0.63 to 1.14, respectively. Eccentric ER strength showed an SMD of 0.47 (95% CI −1.76 to 2.71; two trials, 95 randomized participants; very low certainty). Conventional concentric and isometric ER:IR ratios showed MDs of 0.06 (95% CI −0.54 to 0.65; two trials, 62 participants) and 0.03 (95% CI −0.26 to 0.32; two trials, 138 contributing participants), respectively, both with very low certainty. All primary confidence intervals included no between-group difference. Two-study syntheses were exploratory. Functional-ratio comparisons were reported separately. Conclusions: The available randomized evidence does not establish a clear effect of shoulder-focused exercise on external-rotator strength or ER:IR strength ratios in overhead athletes. All primary pooled confidence intervals included no between-group difference. Because the strength and ratio syntheses included different combinations of trials, the findings do not establish that exercise improves ER strength more consistently than strength balance. More precise trials reporting ER strength, IR strength, and their ratios together are needed.