Refractory period studies in a human neuromuscular preparation.

A subtraction technique has been employed to study refractoriness in the median nerve and thenar muscles in man. The absolutely refractory periods of the distal motor nerve branches and of the muscle fibres were found to be similar, the majority being within the 2.5--3.0 ms range; the values were distributed in a unimodal manner. The relatively refractory periods of the motor nerve terminals were about 5 ms. In some experiments it was possible to record non-propagated potentials at the endplate zones of the muscle fibres.