Effective ways of restoring muscular imbalances of the rotator cuff muscle group: a comparative study of various training methods.

BACKGROUND Many studies have compared different training methods for improving muscular performance, but more investigations need to be directed to the restoration of muscular imbalances. OBJECTIVE To determine the most effective training for altering strength ratios in the shoulder rotator cuff. METHODS Forty eight physical education students were randomly assigned to four groups (12 per group): (a) experimental group who carried out multijoint dynamic resistance training for shoulder internal and external rotation movement (pull ups or lat pull downs, overhead press, reverse pull ups, push ups) (MJDR group); (b) experimental group who exercised the same muscle group using dumbbells weighing 2 kg (isolated group); (c) experimental group who followed an isokinetic strengthening programme for the rotator cuff muscle group (isokinetic group); (d) control group who had no strength training. Testing was performed in the supine position with the glenohumeral joint in 90 degrees of abduction in the coronal plane, with a range of motion of 0-90 degrees of external rotation and 0-65 degrees of internal rotation at angular velocities of 60, 120, and 180 degrees /s. The test procedure was performed before and after the exercise period of six weeks. RESULTS One way analysis of variance found no differences between the groups for the initial tests. Analysis of variance with repeated measures showed that the strength ratios in all the experimental groups had altered after the exercise period, with the isokinetic group showing the most significant improvement. CONCLUSIONS Isokinetic strengthening is the most effective method of altering strength ratios of the rotator cuff muscle.