A Mathematical Model of the Human Respiratory Control System during Exercise

H. Thamrin (Indonesia) and D.J. Murray-Smith (UK)


Biomedical modelling, respiratory control system, exercise, simulation


This paper describes a respiratory control system model and the associated computer simulations for human subjects during incremental exercise, involving work rates from zero up to the highest level in the heavy exercise domain. Modelling the respiratory control system for conditions above lactate threshold has rarely been attempted because many subsystems begin to lose proportionality in their responses. Our model is built on the basis of putative mechanisms and is based on information identified from a large body of published work. Simulation results are presented and validated using experimental results from published sources. The model confirms that the human body employs an open-loop control strategy for ventilation during exercise, which contrasts with the negative feedback control mode employed for the rest condition. It is suggested that control of ventilation simultaneously involves at least two variables, one being proportional to the pulmonary CO2 output and another being proportional to blood acidity.

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