Isometric and Isokinetic Assessment of Shoulder Rotator Muscle Strength, External/Internal Strength Ratios, and Fatigue Response in Competitive Male Gymnasts

This study evaluated shoulder rotator muscle strength, conventional and functional external/internal rotation (ER/IR) strength ratios, and fatigue responses in competitive male artistic gymnasts, compared to a control group consisting of physical education (PE) students. Twenty-six participants were included: 13 competitive gymnasts (22.7 ± 2.3 years) and 13 PE students (22.6 ± 1.5 years), free of shoulder disorders. Shoulder rotator muscle strength was assessed isometrically and isokinetically (60°·s−1 and 180°·s−1) before and after a fatigue protocol comprising 50 maximal concentric internal and external rotations at 240°·s−1. Gymnasts demonstrated significantly higher body mass-normalized peak torque than PE students across the key strength conditions. Before fatigue, conventional and functional strength ratios were generally comparable between groups. Following fatigue, condition-specific changes in ER/IR strength ratios were observed, with gymnasts generally maintaining their pre-fatigue values. Normalized peak torque progressively declined across the 50-repetition protocol in both groups, with no significant between-group difference in the pattern or rate of torque decline. Exploratory analyses of derived fatigue-related measures showed limited and condition-specific between-group differences. Overall, competitive gymnasts demonstrated greater shoulder rotator strength capacity than PE students, whereas the findings did not support a generalized between-group difference in fatigue-related responses. Comprehensive assessment of shoulder strength, ER/IR strength ratios, and fatigue responses may provide useful information for performance monitoring and individualized training.