A method of recording from single muscle fibers or motor units in human skeletal muscle

¹ Biomechanics Laboratory, and Department of Orthopaedic Surgery, University of California, San Francisco, California

It is possible to record single muscle fiber and single motor unit potentials with a tungsten microelectrode inserted percutaneously (without discomfort) into human muscle. Potentials averaging 10–12 mv, 2–4 msec in duration, have been recorded from such muscles as the gastrocnemius and pectoralis major. Firing of the motor units can be followed almost to a maximum isometric contraction without the action potentials being lost in a mass of other motor unit potentials. A technique has also been developed whereby the position of a microelectrode in a human muscle during isometric contraction can be controlled by means of a micromanipulator. The possibility of inserting hard metal microelectrodes into human skeletal muscle percutaneously and positioning them with a micromanipulator substantially widens the range of the experimental work that can be carried on to elucidate the electrophysiological phenomena concerned in human skeletal muscle contraction.

Submitted on August 2, 1963