The effect of exercise on the volume of the blood

The purpose of this investigation is to compare measurements of the blood volume and related factors in normal persons and in cases of heart disease before and after exercise. Previous in-direct studies of the blood volume have indicated that as a result of exercise there is an increase in the concentration of the red blood cells and hemo-globin. Two explanations have been proposed to account for this change; (a) the red cells are ex-truded from the blood depots into the circulation, thereby increasing the volume of the blood and cells (1, 2, 3) and (b) there is a change in the concentration of the blood due to passage of fluid from the blood into the tissues (4, 5). The point at issue here should be readily clari