A Mathematical Model of the Cardiovascular System under Exercise

A mathematical model, based on our previous pulsatile nonlinear multi-element cardiovascular model, was tested and improved to study cardiovascular response under graded exercise levels. Ten healthy subjects were studied using cycle-ergometry exercise test with constant workloads ranging from 25 Watt to 125 Watt. Breath by breath gas exchange, heart rate, cardiac output, stroke volume and blood pressure were measured at each stage. Based on the experimental data, firstly we proved that our previous model is capable to regenerate the cardiovascular variables observed in the subjects under different exercise levels. Secondly, we improved the model by incorporating a robust and efficient function to estimate metabolic demand. Then the new model can estimate both cardiovascular variables and metabolic demand with its simulation results within the range of SD (Standard Deviation, N=10) of the experimental data.