Shoulder functional ratio in elite junior tennis players
Received 27 July 2009; received in revised form 14 October 2009; accepted 17 November 2009. published online 11 December 2009.
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.
aNEO – Orthopedic Sports Medicine Research Center, Rua Botucatu, 591, cj 114, 11° andar, Vila Clementino, São Paulo, SP, Brazil, Cep: 04023-062
bCEFE/UNIFESP-EPM – Center for Physiology Exercises, Federal University of São Paulo, Rua Botucatu, 572, Vila Clementino, São Paulo, SP, Brazil, Cep: 04023-061
ABSTRACT