Studies on Cardiopulmonary Function of Swimming Athletes (2)

Abstract

Roentgenographic heart shadow and EKG of swimming athletes during rest and immediately after swimming were taken and the following results were obtained. A) Roentgenographic heart shadow. i) The enlargement of the heart shadow of sports athletes is fairly reversible and its mechanism is believed to be an adaptation to the working capacity. ii) The heart shadow of swimming athletes immediately after strenuous swim in most cases showed clear-cut contraction and this is believed to be chiefly due to large diastolic residual blood volume at rest. Thus the size of the heart shadow and the degree of contraction does not necessarily match and that an evident correlation with the working capacity was not seen is believed to be due to the inclusion of cases with irreversible change of enlargement. Moreover the working capacity is believed to be greatly influenced by periphera_??_ circulation including the lungs and by the autonomic nervous system and therefore the morphological change of the heart is rather the result of these factors. iii) The oxygen consumption of swimming athletes in step up test when compared with controls was high during exercise load but after completion of loading the opposity, i. e., reduction was seen. On the other hand, the changes of minute volume was about the same as controls. From these observations it is believed that the changes in the oxygen consumption seen in swimming athletes is caused chiefly by the increase of cardiac output. B) EKG i) During rest the ST segment of the left chest leads showed clear upward convex elevation in most of the cases and immediately after strenuous swim the tendency of this curve to become obscure was noted. This is believed to arise from the fact that a different ventricular gradient is seen from that found generaly. ii) Many cases showed a prolongation of the P-R interval during rest but these are some which showed a tendency to show an increase in prolongation immediately after strenuous swim. Therefore it is inadequate to explain a prolongation of P-R interval merely training-vagotony alone.iii) Cases showing incomplete right bundle branch block were relatively common and this finding was especially clear immediately after strenuous swim. This change can be interpreted as being the effect of ventricular dilatation due to extreme loading of the right ventricle but on the other hand, myocardial injury due to over strenuous training cannot be completely ignored.