The decrease in the (V) over-dot-O2 slow component induced by prior exercise does not affect the time to exhaustion

In previous studies decreases in the (V) over dot O-2 slow component were observed after prior heavy exercise. The observed effects after prior low-intensity exercise were rather controversial. The purpose of the present study was to more thoroughly examine the effects of prior low-intensity exercise on the (V) over dot O-2 slow component. Furthermore, it has been suggested that the (V) over dot O-2 slow component may be a determinant of exercise tolerance. Therefore we tested the hypothesis whether an attenuated (V) over dot O-2 slow component induced by prior exercise could affect the time to exhaustion. Ten subjects performed four exercise protocols consisting of heavy cycling exercise (95% (V) over dot O(2)peak) until exhaustion. This constant-load exercise was performed without prior exercise (protocol NPE), or was preceded by 6 min heavy cycling exercise (protocol 6HPE), 12 min low-intensity cycling exercise (protocol 12LPE) or 6 min low-intensity cycling exercise (protocol 6LPE). The (V) over dot O-2 slow component quantified as Delta(V) over dot O2(end-2) (669+/-90 ml x min(-1) in NPE) was significantly reduced after heavy as well as low-intensity exercise (respectively 47%, 29% and 17% in 6HPE, 12LPE and 6LPE). This reduction lead to a significantly lower end (V) over dot O-2 in 6HPE and 12LPE. The time to exhaustion (594+/-139 s in NPE), however, was unaffected by prior exercise rejecting our hypothesis that the attenuated (V) over dot O-2 slow component could improve the capability to sustain exercise performance.