FREQUENCY AND SIZE OF MUSCLE FIBERS IN ATHLETIC BODY BUILD

In one prototype athletic subject and two persons of more average body build complete mid‐point cross sections of the biceps brachii muscle were made. All three cross‐sections were photomicrographed on overlaping fields, and composite photomicrographs of the complete muscle cross section were made. An individual fiber count on these photomicrographs was carried out. The number of individual muscle fibers in the athlete and the other two persons amounted to 316,243, 227,233 and 199,240 fibers respectively. Sampling methods were also tried on the sections for the evaluation of different estimation procedures. Fiber size distributions were arrayed in frequency polygons in each case. Six thousand fibers, randomly chosen from different parts of the section were measured in each case by means of an automatic counter. The mean fiber diameters are 42.26 ± 7.616 μ in the athletic subject and 24.1 ± 4.583 μ and 22.54 ± 4.919μ in the other two subjects. Copyright © 1968 Wiley‐Liss, Inc.