Impaired Upper-Extremity Performance and Isometric Strength in Swimmers With Shoulder Pain: A Cross-Sectional Study

INTRODUCTION: Shoulder pain is common and debilitating in swimmers. This is largely attributed to the repetitive, high-intensity use of the upper limbs during swimming. While many shoulder-specific risk factors have been described, differences in muscle strength and physical performance across the upper kinetic chain between swimmers with and without shoulder pain remain unclear. Our aim was to compare isometric muscle strength and physical performance related to the upper kinetic chain between swimmers with and without shoulder pain. METHODS: We included 34 swimmers (17 with shoulder pain and 17 asymptomatic) in our cross-sectional study. Participants underwent the following tests: Modified Closed Kinetic Chain Upper-Extremity Stability Test; Upper Quarter Y Balance Test; Upper Limb Rotation Test; and isometric muscle strength testing of scapular elevators, internal and external shoulder rotators, lower trapezius, serratus anterior, trunk extensors, trunk flexors and rotators, hip flexors, extensors, abductors, external rotators, and knee extensors. RESULTS: Swimmers with shoulder pain had lower performance in the number of touches (mean difference [MD] = -5.82; 95% confidence interval [CI] -10.15 to -1.50) and in the normalized score (MD = -3.53; 95% CI -5.94 to -1.13) of Modified Closed Kinetic Chain Upper-Extremity Stability Test, the medial direction of the Upper Quarter Y Balance Test (MD = -7.83; 95% CI -14.10 to -1.57), and the Upper Limb Rotation Test (MD = -4.49; 95% CI -7.50 to -1.48) compared with asymptomatic controls. No differences were found in the superolateral, inferolateral, or composite scores of the Upper Quarter Y Balance Test. Swimmers with shoulder pain had lower strength in trunk extensors (MD = -0.85; 95% CI -1.41 to -0.29), quadriceps (MD = -1.07; 95% CI -1.97 to -0.18), and shoulder elevators than controls (MD = -0.50; 95% CI -0.84 to -0.15), while no differences were observed in other muscle groups. CONCLUSIONS: Swimmers with shoulder pain had deficits in physical performance and isometric muscle strength across some components of the upper-extremity kinetic chain.