Acid-Base Regulation and Ventilatory Control during Exercise and Recovery in Man
At rest, 9 millimoles per minute of acid equivalents in the form of CO2 are produced in a typical man. This rate increases to 45 mmol/min during moderate pace walking and up to 200 mmol/min during heavy exercise in a fit man. The primary mechanism by which an overwhelming body acidosis is avoided is by increasing alveolar ventilation (̇VA) in proportion to the metabolic rate. If ̇VA failed to excrete only 10% of metabolically produced CO2, the pH would fall by approximately 0.03 pH units per minute and the pH would decrease to approximately 7.1 after 10 min of walking. Since so many physiological functions depend on the pH of the perfusing blood, a well-designed ventilatory control system would take into account the acid load, including the rate of volatile (carbonic) and non-volatile (e. g. lactic) acid production.
KeywordsLactic Acidosis Work Rate Ventilatory Control Work Intensity Heavy Exercise
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