FIG. 1.

Experimental arrangement. (A) Surface EMG electrodes were attached to six muscles of the ipsilateral leg (indicated by arrows) and two contralateral leg muscles. A potentiometer strapped to the lateral malleolus of the ipsilateral leg registered ankle joint angle. (B) Rectified and unprocessed (lower) soleus surface EMG to show two consecutive bursts of EMG during clonus. The period of relative EMG silence between them was defined as the interburst. Dashed lines and a dotted line mark the beginning of the EMG burst and interburst, respectively. A clonus cycle was composed of one EMG burst and the subsequent interburst.