Influence of rugby practice on shoulder internal and external rotators strength

Shoulder injuries are frequent in rugby, and muscular deficiency and/or imbalance of the internal (IR) and external (ER) shoulder rotators are considered as probable mechanisms of shoulder injuries. The purpose of this study was to investigate whether the rotators strength imbalances occur in rugby players by comparing IR and ER strength and ER/IR ratios between rugby players (RP) and nonathletic subjects. Fourteen RP and 19 healthy nonathletic subjects were evaluated in this cross-sectional controlled study with a Con-Trex ((R)) dynamometer. IR and ER isokinetic strength were performed at 60 degrees . s (-1) and 240 degrees . s (-1) in concentric, and 60 degrees . s (-1) in eccentric, for both sides. Strength values were higher for RP than nonathletic ones ( P<0.05), but if peak torque was normalised to body weight, there were no significant differences. There was no significant effect of laterality on the IR and ER peak torque, and no significant influence of rugby and/or laterality on the ER/IR ratio. In conclusions, our results reported no rotators muscles imbalance in RP as a possible risk factor of glenohumeral injury.