Exercise respiratory pattern in elite cyclists and sedentary subjects

We investigated the breath-by-breath pattern of ventilatory response to bicycle exercise in seven elite male cyclists (VO2max = 71.7 ml X min-1 X kg-1) and ten sedentary males (VO2max = 47.3 ml X min-1 X kg-1) to analyze differences in breathing patterns between individuals with normal and high exercise ventilations (VE). The mean VEmax of the athletes (ATH) exceeded that of the sedentary subjects (SED) by 34.6% (183 vs 136 l X min-1) and was proportional to the difference in VCO2max between the groups (5.9 vs 4.23 l X min-1). The ATH used an average of 89% of their 15-s maximum voluntary ventilation (MVV) during maximum exercise while SED used only 71%. The ATH had slightly, but not significantly, larger vital capacity (FVC). Both groups used about half of their FVC at maximum tidal volume (VT), VT was 47% and 49% of FVC in ATH and SED, respectively. The ATH achieved the higher VEmax by achieving a greater increase in respiratory frequency (63/min vs 49/min), which was accomplished by significant decreases in both inspiratory (T1) and, more importantly, expiratory (TE) time. There was a tendency for athletes to have a somewhat more regular breathing pattern. Both 1/T1 and mean inspiratory flow (VT/T1) were highly correlated with VE, but there were no differences in these relationships between ATH and SED. Highly-conditioned athletes, therefore, respond to the increased demand for CO2 elimination by utilizing a higher respiratory frequency achieved through a reduction of both inspiratory and expiratory duration, but not by utilizing a larger tidal volume (i.e., as percent FVC) than less fit individuals.