[Physical activity and cardiorespiratory equilibrium]

Abstract

Nowadays it is believed that each patient can participate in a physical activity adapted to his or her pathology, based on a rationale. In cardiorespiratory patients, the crucial point is an excessive hyperventilation at submaximal exercise. The "dyspnea spiral" is a good model for understanding this particular response. The lung and cardiac function impairment induces dyspnea during moderate exercise. To avoid this dyspnea, the patient develops a sedentary lifestyle which induces deconditioning, i.e., regression of the aerobic pathway. For a given load, anaerobic glycolysis plays an increasingly important role. This leads to an increase in blood lactate concentration during exercise. The buffering of lactic acidosis by blood bicarbonate produces an additional amount of CO2, and results in a proportional increase in ventilation requirement, which increases dyspnea. The patient again decreases his physical activity, and the downward spiral continues. Thus in cardiorespiratory patients dyspnea has two origins. The primary disease is the heart or lung disease. The deconditioning is a true secondary disease. The aim of exercise training in cardiorespiratory patients is to treat secondary disease in order to relieve dyspnea, and increase exercise tolerance and therefore quality of life. Training sessions usually last 45 minutes, two or three times a week, at the intensity of anaerobic threshold, this latter being more precise and individualized than an arbitrary percentage of maximal heart rate. The results show a decrease in ventilation at submaximal level of exercise up to 20-30% with a systematic alleviation of dyspnea and an increase in exercise tolerance and in quality of life. Exercise training in considered to be the best treatment of dyspnea in cardiorespiratory patients.