Studies of the movement of pronation-supination of the forearm during pursuit tracking task.

In ten healthy men, we studied on the movement in pronation-supination of the forearm. A luminescent spot oscillating semicircularly on the surface of Braun tube was made to track by the movements of pronation-supination of forearm with the elbow flexed to 90°. EMGs by electrodes with 70μ enamel coating embeded in 4 muscles comprising the pronator quadrtus, the pronator teres, the supinator and the biceps brachii were integrated at the time-constant of 0.16 sec to get the integrated wave. Then mean values of difference between peak and bottom in integrated ENG were calculated and plotted in each frequency of 0.5 to 3Hz, and in the same way, mean values of bottom were obtained as the fruquency response of EMG. It is considered that each frequency responses represent dynamic or static activities of EMG respectively.In this series, the complete pursuit was done within 1Hz. The pronator quadrates and the supinator indicate high activities below 1Hz. The pronator teres and the biceps brachii show high activities above 2Hz. On the other hand, static activities of EMGs of 4 muscles, all indicate high activity above 2Hz.