The conduction velocity of the ulnar nerve and the spinal reflex time measured by means of the H wave in average adults and athletes.

Numerous papers on the conduction velocity of the nerve fibers have been published since the original report of Helmholtz and Baxt (1883). Among these papers, an experimental result was presented by Wagman and Lesse (1952) that the maximum conduction velocity of human ulnar nerve fibers may be attained as early as the fourth to fifth years of life and that it may not increase from these years onwards with the growth of the body. Their result is in agreement with Rexed's (1944) histological data that the fiber size distribution in the ventral root attains the adult distribution between the ages of five and nine years. Recently Thomas and Lambert (1960) have measured the conduction velocity of the ulnar nerve as well as the spinal reflex time by means of the H wave on human subjects and have reached the same conclusion as Wagman and Lesse. In the present experiments, the maximum conduction velocity of ulnar nerve fibers and the spinal reflex time in the tibial nerve by means of the H-wave have been measured, in the first place, on 30 average adults under the special con sideration of room temperature. In the second place, they have been measured also on 38 selected athletes for comparison with above noted data in order to elucidate whether the maximum conduction velocity of nerve fibers could increase following physical exercise during youth.