Background. This article presents the results of research on the impact of muscle training using Kotz phasal currents on rehabilitation outcome in patients with degenerative disease of the femoropatellar joint. <br /> Material and methods. Our research involved 40 patients undergoing isometric exercises of the quadriceps muscle of the thigh. In 20 of these patients (the experimental group) we also applied Kotz phasal currents. In the course of rehabilitation we measured any changes occurring in the circumference of the thigh 10 cm from the base of the patella, as well as muscle strength on the Lovett scale.<br /> Results. A significantly greater reduction in pain was achieved in the experimental group. After the first two weeks, the differences between the two groups in the circumference of the thigh and in muscle strength were only slight, but after the next two weeks visible changes emerged in both parameters. In the control group there was slight improvement in circumference of the thigh, but muscle strength remained unchanged. <br /> Conclusions. The results we obtained indicate that training with Kotz currents and isometric exercises are an effective means of treatment in rebuilding muscle mass and strength.