To determine the effects of isokinetic resistance training of the quadriceps, 25 male volunteers were randomly assigned to five training groups: Concentric Slow (CS), Concentric Fast (CF), Concentric-Eccentric Slow (MS), Concentric-Eccentric Fast (MF), and Control (C). In training, subjects performed 20 contractions of each quadriceps using either 60 degrees/sec or 180 degrees/sec, for both sides, five days per week for 12 weeks. Testing consisted of measurement of peak torque, at intervals of 60 degrees/sec across a spectrum of velocities ranging from plus to minus 240 degrees/sec, at 0, 4, 8, and 12 weeks. Repeated MANOVA using planned comparisons showed that all trained subjects made significant peak torque gains (p < .05), but that the gains made by MS and MF were greater. These findings suggest that the addition of an eccentric training component to a concentric isokinetic training program may allow greater peak torque gains regardless of the velocity.