Article

With hemiplegic subjects the EMG-force ratio is often increased. Amongst others this can be due to (i) an increased activity of antagonistic muscles, (ii) a change of the composition of the muscle with respect to motor unit type of (iii) a very early appearence of fatigue. In order to test these hypotheses a number of experiments were performed at the plantar and dorsal flexors of the foot with 19 hemiplegic subjects. The exerted isometric force and the EMG signals of agonist and antagonist were recorded during short contractions and during a long contraction at 50% MVC. Afterwards these signals were analysed (amplitude histogram and power density function). The twitch contraction curves were determined of the anterior tibial and the triceps surae muscles. From these the twitch contraction time and the half relaxation time were calculated. The data of the hemiparetic side were compared with the unaffected side. We found a large decrease of maximum force and often a prolonged contraction time at the hemiparetic side. We found no significant increase of antagonist activity and no significant differences in the changes of the EMG during prolonged contractions.

Langue : ANGLAIS

Identifiant basis : 1985002376