The Effects of Isokinetic Versus Plyometric Training on the Shoulder Internal Rotators

Abstract

Plyometric training has become a popular training and rehabilitation tool. The purpose of this study was to compare the effects of plyometric and isokinetic concentric/eccentric training of the shoulder internal rotators. Female subjects (N = 78) were randomly assigned to three groups: control, isokinetic training, and plyometric training. Pre-/posttesting measurements included: 1) concentric/eccentric isokinetic power measurements of the shoulder internal rotators at 60 degrees/sec, 180 degrees/sec, and 240 degrees/sec; 2) kinesthetic measurements of shoulder internal rotation, external rotation < 45 degrees, and external rotation > 45 degrees; and 3) a softball distance test. Both groups trained twice a week for 8 weeks. Power and kinesthetic data were analyzed using multiple analyses of variance with repeated measures. A one-way analysis of variance was performed on the softball throw data. No significant (p < .05) pre-/posttest differences were found with kinesthetic testing or the softball throw. Pre-/postpower differences were significantly greater for the isokinetic group at 60 degrees/sec eccentric, 120 degrees/sec concentric and eccentric, and 240 degrees/sec concentric and eccentric. Isokinetic training of the shoulder internal rotators increases isokinetic power, but neither isokinetic nor plyometric training resulted in a functional improvement with the softball throw.