Comparative study of isokinetic eccentric and concentric quadriceps training

The purpose of this study was to compare the effects of eccentric and concentric isokinetic training exercises on eccentric and concentric quadriceps performance in 63 healthy subjects during a six-week training period. The subjects were randomly divided into three groups: eccentric training, concentric training, and no training. Members of the training groups exercised their right quadriceps only. Orientation, training, and testing were performed on a computer-assisted isokinetic dynamometer (KIN-COM) at 100°/sec. All subjects were tested concentrically and eccentrically on both quadriceps; and peak torque, total work, and position angle at peak torque were measured. Analysis of variance and post hoc analyses were performed on the mean changes (pretest and posttest differences) for all groups. The concentric training group demonstrated the most significant increases in concentric torque and work; the eccentric training group demonstrated the most significant increases in eccentric torque and work. No significant changes were seen in the untrained left limbs of any group. These results support the concept of mode specificity in isokinetic exercise training.