Shoulder rotator isokinetic strength profile in young swimmers

Considering that some studies suggest that shoulder rotators muscle imbalances are related to joint pain and injury, and that there are no normative data for young swimmers, the aim of this study was: i) to describe the muscle balance, fatigue and isokinetic strength profile of the shoulder rotators in young swimmers; ii) to compare the results between swimmers and a group of young non-practitioners; iii) to contribute to the acquisition of normative data of unilateral ratios of shoulder rotators. We evaluated the shoulder rotators concentric strength and unilateral ratios (ratio between torque of external and internal rotators) of 60 swimmers (age: 14.55 ± 0.5 years old; body mass: 61.16 ± 7.08 kg) and 60 non-practitioners (age: 14.62 ± 0.49 years old; body mass: 60.22 ± 10.01 kg). The evaluation was performed in the sitting position (90° abduction and elbow flexion) at 60°.s^-1 and 180°.s^-1 angular speeds using an isokinetic dynamometer (Biodex System 3). The results of the fatigue ratios revealed no differences between the groups. Swimmers showed unilateral ratios of 73.39 ± 17.26% in the dominant limb (DL) and 77.89 ± 15,23% in the non-dominant limb (NDL) for assessments at 60°.s^-1. At 180°.s^-1, ratios were 74.77± 13.99% for DL and 70.11 ± 14.57% for NDL. Swimmers presented greater muscle imbalance, and differed from non-practitioners in the ability to produce power with the internal rotators, which was significantly higher in the former group.