Effect of Exercise on Circulatory Dynamics of Normal Individuals

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Abstract
Studies of cardiac output and pulmonary arterial and "capillary" pressure were performed in 7 normal individuals at rest and during exercise in the recumbent position. All showed an increase of cardiac output and arterio-venous O2 difference. At O2 consumptions exceeding 400 ml./min./sq. cm. body surface, a rise of pulmonary arterial pressure, negligible rise of pulmonary "capillary" pressure, widening of the PA-"PC" mean pressure gradient, and no significant change of pulmonary arteriolar resistance occurred. Pressure-flow relationships in both left and right ventricles were analyzed. Work of the right ventricle against pressure increased about 3-fold and that of the left ventricle about 2 times over the resting levels when exercise produced an oxygen consumption of 500 ml./min./sq. m. body surface.