A mathematical model of cardiovascular response to dynamic exercise

A mathematical model of cardiovascular response to dynamic exercise is presented. The model includes the pulsating heart, the systemic and pulmonary circulation, a functional description of muscle exercise hyperemia, the mechanical effects of muscle contractions on hemodynamics, and various neural regulatory mechanisms working on systemic resistance, venous unstressed volume, heart rate and ventricle contractility. These mechanisms comprehend the direct effect of motor command signals on cardiovascular and respiratory control centers (the so called central command), arterial baroreflex and the lung-stretch receptor reflex. The model is used to simulate the steady state response of the main cardiovascular hemodynamic quantities (systemic arterial pressure, heart rate, cardiac output, systemic vascular conductance, and blood flow in working muscle) to various intensity levels of two-legs dynamic exercise. A good agreement with physiological data in the literature has been obtained. The model sustains the hypothesis that motor command signals emanating from cerebral cortex provide the primary drive for changes of circulation and respiration during exercise. The model may represent an important tool to improve understanding of exercise physiology.