Abstract
Evidence exists to indicate that prolonged ventilatory work fatigues respiratory muscles and may limit exercise tolerance. However, the effects of short-duration, high-intensity ventilatory work on subsequent exercise remains in question. We tested the hypothesis that intense short-term volitional hyperpnea would result in respiratory muscle fatigue and would therefore hinder subsequent exercise tolerance. Pulmonary function was determined in ten healthy, male subjects before and after two constant load exercise tests to exhaustion on a cycle ergometer. Test 1 was a preliminary test to determine V̇O2max, peak exercise V̇E, and peak exercise power output. Test 2 was a constant load (85% peak power output) exercise test to exhaustion. Test 3 was identical to test 2 but was preceded by 10 min of volitional, isocapnic hyperpnea (85% of peak exercise V.E) at a controlled frequency and tidal volume. Pulmonary function measures (FVC, FEV1, FEV1/FVC, and peak flow) were not significantly (P < 0.05) altered by the volitional hyperpnea. Ventilation and gas exchange variables (V̇O2, V̇E, f, end-tidal PO2 and PCO2, V̇E/V̇O2, V̇E/V̇CO2, %SaO2) during exercise and time to exhaustion were not significantly (P < 0.05) different between treatments. These experiments failed to show any effect of short-term ventilatory work on pulmonary function or subsequent exercise performance.
Key words
Exercise - respiratory fatigue - pulmonary function
