Indirect measurement of left ventricular function during exercise.

The electrocardiogram, phonocardiogram and carotid pulse curve were recorded during increasing work loads on an electrically braked bicycle. Heart rate increased linearly with increasing work loads while total systole and tension period decreased. In contrast, during the first periods of light work, systolic ejection time increased. As work load increased, the ejection period also decreased. The findings were interpreted as indicating an early increase in stroke volume with exercise and a later increase in the velocity of ejection.