Voluntary control of the rate of increase of the isometric tension of human muscles.
Experiments were made with eight subjects to study the possibilities for voluntary control of the rate of increase of isometric muscle tension in m. biceps brachii and m. interosseus dig. dors. 1. In four consecutive experiments the voluntary effort was increased until maximum muscle tension was achieved. Each subsequent experiment was at a higher velocity. All subjects were able to rank the velocities. Repetition of performances with respect to the velocity values was low. A considerable difference existed between the group of chosen velocities which were very similar in the different subjects, and the maximum possible velocities which differed for each subject. Individually different was also the maximum muscle tension which in its turn was in a limited dependence on the rate of increase of the tension. No stable relations were established among the velocities, which could correspond to a standard description elaborated in the system for motor control.