Surface-EMG analysis of rectus femoris in patients with spastic hemiparesis undergoing rehabilitation treatment.

In the present study a surface-EMG investigation of the rectus femoris muscle was performed in patients with spastic hemiparesis before and after rehabilitation treatment. The EMG activity was detected during 50% of the maximum voluntary contraction by means of FFT automatic analysis; the mean power frequency (MPF) and the time-course of the frequencies of the surface-EMG signals showed significant changes after physiokinesitherapy. In hemiparetic patients a particular distribution of the frequencies of the surface-EMG signals towards the lowest values were observed. These findings could be related to the preferential atrophy of type II fibers which has been demonstrated in morphological studies. Furthermore the surface-EMG analysis after a period of rehabilitation treatment showed some significant modifications of MPF and time-course of the EMG signals. These changes corresponded to an improvement of the spasticity as evaluated by clinical rating-scale. This neurophysiological investigation seem to be a simple and reliable method for better evaluating some effects of the rehabilitation therapy.