Torque variations during repeated passive isokinetic movements of the knee in subjects with Parkinson's disease and healthy control subjects.

The purpose of this study was to quantify response variations during isokinetic passive movements of the knee in subjects with Parkinson's disease. Parkinsonian patients demonstrated a greater decrease of resistive torque compared to healthy control subjects, particularly in tests at higher velocities and during knee flexion movements. Responses were influenced by electromyographic activity in stretched and shortened muscle groups and also by mechanical factors. The results indicate that repetition of movements needs to be taken into account when measuring hypertonia in parkinsonian subjects.