The authors have studied the efficacy of 3 different muscle training programs (electromyostimulation, isokinetic training and isometric training) in cases of patellar chondromalacia. The evaluation of the results was made by measuring the isokinetic strength on a Cybex II+ dynamometer at a low (30 degrees/sec) and a high (300 degrees/sec) angular velocity. The clinical evaluation was based on a modified score determined by the Arpege group. The results showed a better improvement of the muscular strength after electromyostimulation or isokinetic training. The clinical improvement was better on patients of groups I and III.