Conduction velocity in human muscle fibers in situ. Study in upper and lower limbs in healthy adults.

The muscle fibers of the human biceps brachii and vastus medialis muscles were stimulated with low voltages in their distal portion by means of monopolar needles in 50 healthy adults. The electrical activity was recorded proximally by means of a SFEMG electrode. The conduction velocity of the muscle fibers in situ calculated with this method had a Gaussian distribution for both muscles, showed values slightly higher in males than in females, did not decrease significantly with ageing, and was significantly related to limbs perimeter. The recorded potentials and their propagation velocity were the same before than after curarization. The possible interest of the method for testing the muscle fiber function and size in pathological conditions of the nerve and muscle is suggested.