Impulse activity of a single motor unit upon the rhythm of the summated muscle activity

The impulses of single motor units (MUs) are recorded using the method of selective leading off with surface bipolar electrodes with small interpolar distance. Parallel recording is made of the summated EMG and of its apparatus-transformed form-the mean voltage curve of the EMG. The correct position of the electrodes with regard to the MU is controlled by means of a vector-electromyographic (VEMG) method. The statistical parameters of the impulse series of the individual MUs and of the groups of impulses in the summated EMG are determined, as well as the time interrelations between the impulses of the selected MUs and the groups of impulses in the mean voltage curve of the EMG. The delay in the appearance of the impulses from the selected MUs with regard to the beginning of the group of impulses, proved a statistically distributed value according to a bimodal type which becomes more pronounced upon rating to the intervals.