Shoulder rotators isokinetic profile according to instability and/or sport specificity: Implications for rehabilitation: Shoulder rotators isokinetic profile.

Abstract

To (i) describe the shoulder rotator muscle profiles across healthy, unstable, and athletic contexts, and (ii) to compare the usual Peak Torque (PT-method) and the Angular Range (AR-method). Retrospective analysis of data collected cross-sectionally. Hospital. Each participant participated in isokinetic evaluations of the shoulder rotator muscles at 60°.s^-1 (concentric/eccentric) for both shoulders. 239 participants of 24.7 (7.5) years INTERVENTION: None. We recorded the PT and AR mean torque by 10°, and we calculated the antagonist/agonist ratios. We used a two-way repeated measures ANOVA with a correction for multiplicity to compare laterality (i.e., side-to-side) and contexts (i.e., no-overhead sports healthy, no-overhead sports with unstable shoulder, overhead sports healthy and overhead sports with unstable shoulder RESULTS: Concentric PT of external rotators were significantly lower in no-overhead athletes with shoulder instability than healthy no-overhead athletes (p=0.007) and than healthy overhead athletes (p=0.029). The AR highlighted significant (p<0.05) lower concentric external and internal rotator muscles strength: i) in no-overhead athletes with shoulder instability than in healthy no-overhead athletes; ii) in healthy overhead athletes than in healthy no-overhead athletes; iii) in no-overhead athletes with shoulder instability than in healthy overhead athletes. No significant difference was observed in the eccentric modality or in the PT/AR ratios. Significant side-to-side differences (p<0.05) between dominant and non-dominant sides were reported by both PT and AR methods. Only the concentric muscle profiles differed across context groups. The AR allowed for a more precise detection of shoulder muscle adaptations by identifying unique muscle signatures in the moment-angle relationship. These 10° angular range measurements offer complementary information and enhance the clinical utility of isokinetic profiling compared to the traditional PT-method.