Influence of Body CO2 Stores on Ventilatory-Metabolic Coupling During Exercise
During the steady state of moderate exercise, ventilation (̇VE) is closely matched to pulmonary gas exchange rates (̇VO2, ̇VCO2) and, therefore, to current metabolic demands. This maintains arterial PCO2(PaCO2), pH (pHa) and PO2 at, or close to, their resting levels. For the nonsteady state, however, the presence of intervening gas stores and circulatory delays between the sites of increased metabolic rate and the lungs transiently dissociates pulmonary and tissue gas exchange. The influence of the appreciable body CO2 capacitance educes ̇VCO2 kinetics which are substantially slower than for ̇VO2 but similar to those of ̇VE.1, 2, 3, 4 The close co-relation between ̇VCO2 and ̇VE kinetics (with little change of PaCO2) has led to the proposal of a CO2-linked control of ̇VE during moderate exercise, although the precise mechanisms involved remain conjectural.
KeywordsLactic Acidosis Carotid Body Anaerobic Threshold Moderate Exercise Lactate Threshold
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