Problems with the hyperventilatory response to exercise and hypoxia.

Abstract

To achieve the optimal ventilatory response to heavy exercise, several criteria must be satisfied. First, alveolar hyperventilation must be adequate to meet not only the rising CO2 flow to the lungs but also to compensate the progressive development of metabolic acidosis and to ensure a high overall \(\rm\dot{v}\)A/\(\rm\dot{Q}\)C and diffusion gradient in the face of marked reductions in mixed venous PO2 and shortened capillary transit time. Secondly, the mechanical limits of the lung and chest wall — in terms of respiratory muscle force, energy stores and rate of energy supply — must be sufficient to meet these ventilatory demands. Third, the regulation of respiratory muscle length and the timing of muscle contraction must be regulated so as to optimize chest wall function.