The aim of the study was to investigate the effect of a muscular training program on soccer players’ performance which initially appeared imbalanced or bilaterally asymmetrical. During the preparation period, 35 soccer players performed an isokinetic measurement of knee flexors and extensors (60°.-1 and 180°sec.-1). 15 of these had muscular imbalances or deficits and followed a specific isokinetic training program for 2 mo., 3 times per week. After the completion of the isokinetic training program, the 35 players underwent the same isokinetic test. Significant differences were noted between the pre- and posttraining measures at both angular velocities in peak torque values, in differences from one limb to the other, and in peak torque ratios for flexors and extensors. Consequently, the application of this specific isokinetic training program can restore imbalances in knee muscle strength efficiently.