"A short leg can be moved more rapidly than a long one," the study observed. "Alternatively, the short legs may not be directly associated with the high speed but, indirectly, through an association with the large muscles also characteristic of the sprinter. In an analysis of the body measurements of ordinary students, we found that men with big muscles had relatively short legs. This comes about during growth as a result of muscular boys maturing and ceasing growth slightly earlier than others. As the legs are growing relatively faster than the trunk just before puberty, an early puberty deprives them of further increments more than it does the trunk. It is for the physical educationist to analyze whether the lever effect or the large muscle size is of greater importance in sprinting; practically, the two go together.
"This explanation would not hold for the long-distance runners; here it seems certain that short legs confer some mechanical and physiological advantage. The walkers also have short legs, and perhaps the speed of movement of the ankle is of first importance to them as to the sprinter. A long-legged man spends too much time with his feet in the air. The few 110-meter hurdlers, be it noted, do not have the short legs of their flat-racing companions. The hurdler has to clear the hurdles, and a center of gravity high above the ground is imperative for him. Only a very large hurdler indeed could afford to have short legs relative to his trunk. This is an event where one might expect, and within limits, one obtains, Negro predominance."
Other studies found further physical differences in the races. Albert Damon of Harvard University's department of anthropology, writing in Human Biology, reported on an anthropometric survey undertaken at Fort Devens, Mass. with respect to lung function. The study covered 529 Army drivers.
"On forced expiration," the article reported, "the vital capacity of some 30 soldiers approached or exceeded the six-liter limit of the recording machine. Surprisingly, none of these 30 pulmonary athletes was a Negro, although at least five Negroes might have been expected, since 17% of the soldiers were Negroes and since the Negroes as a group seemed to try as hard as the whites, [and] were no smaller and were actually more muscular and stronger."
While stressing the importance of social, cultural and motivational factors that have kept the black man from excelling in some sports, Dr. Edward E. Hunt Jr., professor of anthropology at Pennsylvania State University, has noted that the black athlete has "hyperextensibility—or what the layman might call being double-jointed."
"The Negro has more tendon and less muscle than the white," he said. "The black man's heel doesn't protrude as much and his leg and foot give him tremendous leverage for jumping."
On the other hand, since the black athlete tends to have less body fat, Dr. Hunt observed, his muscles tend to get chilled sooner in cold climates, and this might affect his performance in such sports as ice hockey, or football when played in extreme northern areas.
Then there is the theory of Lloyd (Bud) Winter, the former San Jose State track coach, who holds that black athletes "have a distinctive ability to relax under pressure."
"Their antagonistic muscles—the muscles that extend—stay loose," he says. "I remember one of my quarter-milers, Thelmo Knowles. I kept saying to him, automatically, to stay loose. One day Thelmo answered, 'Coach, if I relax any more I'm going to fall in a heap.'
"What heritage or heredity brought the black athlete this ability to keep out tension, no one knows. Yet, prior to the big day the black athlete, as a rule, can go through his daily motions or his sleep period normally, and when the big moment comes he can react normally. In white athletes the conscious mind often takes over and the tensions mount."