Isokinetic Strength and Electromyographic Analysis of Knee Muscles in Parkinsonian Patients and Normal Subjects

Abstract

The purposes of this study were to analyze the peak torque and the electromyographic (EMG) activity of knee flexors and extensors at different speeds in normal subjects and patients with Parkinson's disease (PD). Five Parkinsonian patients (mean age 59.0 years, range 45 to 76 years old) and fifteen normal subjects (mean age 57.1 years, range 44 to 75 years old) participated in this study. The Parkisonian patients in Hoehn and Yahr stage of II-III were ambulatory and the mean duration of illness were 8.2 years (range 1-15 years). All subjects received isokinetic muscle strength testing of unilateral knee flexors and extensors by Cybex 6000 dynamometer (Lumex Co., U.S.A.). The patients sat in upright position and surface electrodes were placed at knee flexors and extensors to record quadriceps and hamstring EMG. The results were: (1) the concentric peak torques of knee extensors and flexors in Parkinsonian patients at 60°/sec, 90°/sec and 120°/sec were significantly less than those in normal subjects, (2) the initial EMG activities at 60°/sec in Parkinsonian patients were significantly less than that in normal subjects, (3) co-contraction ratios of flexors at 60°/sec and knee extensors at 120°/sec in Parkinsonian patients were significantly higher than that in normal subjects. The conclusion was that the muscle strengthening exercise combined with reciprocal inhibition (relaxation), especially at slow speed, would be beneficial for Parkinsonian patients.