The effects of concentric versus eccentric isokinetic strength training of the rotator cuff in the plane of the scapula at various speeds.

This study compares the effects of three modes of isokinetic resistance training at the shoulder--concentric, eccentric, and a combination of both concentric and eccentric, with a group that received no training at all. Twenty-eight healthy volunteers (male and females), 18 to 36 years of age, with no history of shoulder pathology, were randomly assigned to one of four groups; concentric training, eccentric training, a combination of both concentric and eccentric training, or control (no training). Testing and training of the dominant shoulder was performed on an isokinetic dynamometer. All subjects were pretested and post-tested both concentrically and eccentrically for humeral internal/external rotation and abduction at speeds of 60 degrees/sec and 120 degrees/sec. Each training session consisted of a total of twelve sets of ten maximal repetitions, and was repeated three times a week for four weeks. The absolute and percent difference in peak force and peak torque for each group between the pretest and post-test was calculated for each combination of position, mode, and speed. A significant difference between the concentric/eccentric group and the eccentric group was found for abduction (p < 0.05). The eccentric group showed a significantly greater increase from the pretest to post-test for absolute differences in peak force and peak torque compared to the concentric/eccentric group (p < 0.05).