THE CIRCULATION IN ATHLETES 1

Abstract

Measurements of the arteriovenous O2 difference, O2 consumption, min. vol. output, stroke vol., vital capacity, cardiac size, circulation time, venous pressure, arterial pressure, and heart rates were made of 14 college athletes, and to serve as controls of 11 healthy, young, adult [male][male] who were living a sedentary life. Electrocardiograms were also recorded. The measurements of the cardiac output were made by the acetylene method, 3 samples of gas being taken. All measurements were made while the individuals were in a basal metabolic state. In athletes, the average arteriovenous O2 difference was 63.9 cc, cardiac output 2.12 l./sq.m./min., stroke vol. 65 cc. per beat, stroke vol. per kg. 0.80 cc, left ventricular work per beat 1.06 g.m. per kg., venous pressure 92 cm., circulation time 15.4 sec., transverse diam. of heart 13.3 cm., and cardio-thoracic ratio 42.9%. With one exception, there was no significant difference in these objective measurements between those made on the athletes and those derived from the normal sedentary group. The stroke vol. of the athletes (65 cc.) was slightly greater than in the normal subjects (59 cc). This difference was apparently related to body size since the stroke vol. per kg. of body wt. and the cardiac index for the 2 groups were approximately the same. The values for the cardiac output and related measurements, as well as the form of the electrocardiograms, were within the accepted limits of normal in every case of both groups. The work of the left ventricle, when plotted against the heart vol., was found to be proportional to the size of the heart in every case. Although these studies, carried out under basal metabolic conditions, revealed no significant differences between the functional capacity of the heart of the athletes as compared with the normal control subjects, it obviously does not necessarily follow that the individuals used as controls can perform the same amt. of work as efficiently as the athletes.