Medical aspects of competitive athletics.

In longer races an increasing proportion of the energy for running comes from the aerobic mechanism of energy liberation. Aerobic mechanisms contribute just over half the total energy required in running a mile but more than three-quarters of the energy required in running three miles. In the presence of adequate supplies of oxygen, pyruvic acid is not converted to lactic acid but itself undergoes oxidative reactions. Since the anaerobic reactions are a relatively inefficient source of energy, the