In the process of training, the getting wind, as it is called, is largely a gradual increase in the capability of the heart.... The large heart of athletes may be due to the prolonged use of their muscles, but no man becomes a great runner or oarsman who has not naturally a capable if not a large heart.1 THE heart of an athlete has certain functional and morphologic adaptations that distinguish it from other hearts. The capacity to perform vigorous physical activity depends on the integrated functioning of many systems. The cardiovascular system plays a pivotal part, since continuous muscular . . .