Abstract
The purpose of the present study was to determine whether the linear relationship between CO2 output (V˙CO2) and pulmonary ventilation (V˙ E) is altered during incremental cycling performed after exercise-induced metabolic acidosis. Ten untrained, female subjects performed two incremental cycling tests (15 W · min−1 up to 165 W) on separate days. One incremental exercise test was conducted without prior exercise, whereas the other test was preceded by a 1-min bout of maximal cycling. The ventilatory equivalent for O2 (V˙ E/V˙O2) was only elevated above control values at 15–60 W during incremental cycling performed after high-intensity exercise. In contrast, the ventilatory equivalent for CO2 (V˙ E/V˙CO2) was significantly increased above control levels at nearly every work stage of incremental work (all except 165 W). Hyperventilation relative to V˙CO2 was confirmed by the significantly lower end-tidal CO2 tension (P ETCO2) obtained throughout the incremental cycling that was performed after high-intensity exercise (except at 165 W). V˙ E and V˙CO2 were significantly correlated under both treatment conditions (r > 0.99; P < 0.001). Moreover, both the slope and y-intercept of the linear regression were found to be significantly elevated during the incremental cycling performed after high-intensity cycling compared to control conditions (P < 0.01). The increase in the slope of the V˙ E-V˙CO2 relationship during incremental exercise performed under these conditions does not represent an uncoupling of V˙ E from V˙CO2, but could be accounted for by the significantly lower P ETCO2 observed during exercise.
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Accepted: 20 June 1997
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Schneider, D., Berwick, J. V˙E and V˙CO2 remain tightly coupled during incremental cycling performed after a bout of high-intensity exercise. Eur J Appl Physiol 77, 72–76 (1997). https://doi.org/10.1007/s004210050302
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DOI: https://doi.org/10.1007/s004210050302