The aim of the investigation was to study and compare the effect of two basically different training methods on muscle strength and knee function on a consecutive and prospective series of 26 conservatively treated patients with chronic anterior cruciate ligament injury. The two training models were: model Q directed towards specific training of knee extensor muscle strength and model F aiming at training of the lower extremity and trunk muscles in functional weightbearing patterns. The parameters evaluated were: isometric and isokinetic muscle strength, a performance test (one-leg hop test), and a functional score. The results after a three-month training period showed in both groups a significant increase of muscle strength in both knee extensors and knee flexors. No significant difference of isokinetic strength values between the two groups was observed. The isometric gain of knee extension was significantly higher in the Q group. The one-leg hop test value and the functional score were also significantly increased in both groups. However, the hop test indicated a more favourable result in the group who were trained functionally.