Shoulder functional ratio in elite junior tennis players

Abstract Objective To evaluate shoulder rotation strength and compare the functional ratio between shoulders of elite junior tennis players. Design This cross-sectional study evaluated muscular rotation performance of 40 junior tennis players (26 male and 14 female) with an isokinetic dynamometer. Main outcome measures Strength variables of external (ER) and internal rotators (IR) in concentric and eccentric modes were considered. For the peak torque functional ratio, the eccentric strength of the ER and the concentric strength of the IR were calculated. Results All variables related to IR were significantly higher on the dominant compared to the non-dominant side in males and females ( p < 0.05), but only boys exhibited this dominance effect in ER ( p < 0.05 and p < 0.001). Regarding functional ratios, they were significantly lower for the dominant shoulder ( p < 0.001) and below 1.00 for both groups, indicating that the eccentric strength of the ER was not greater than the concentric strength of the IR. Conclusion Elite junior tennis players without shoulder injury have shoulder rotation muscle strength imbalances that alter the normal functional ratio between rotator cuff muscles. Although these differences do not seem to affect the athletic performance, detection and prevention with exercise programs at an early age are recommended.