By the treatment of the chondropathia patellae for example it is indispensable to use a closed-chain strength training, which allows to reach all major muscles of the lower extremity and gives the impulse for a static and dynamic accommodation. Isolated overloading or provocation of muscular imbalance can be counteracted. The following study will prove the practical use of a linear isokinetic device on the treatment of the chondropathia patellae.