The effect of prior high-intensity cycling exercise on the VO2 kinetics during high-intensity cycling exercise is situated at the additional slow component

In previous studies conclusions about the effect of prior exercise on (V) over dot O-2 kinetics of subsequent high-intensity exercise are generally based on observed changes in the overall (V) over dot O-2 response without considering the effects on the (V) over dot O-2 fast and slow component. The aim of the present study was to examine the effect on the (V) over dot O-2 fast and slow component separately. Therefore 10 subjects performed an exercise protocol consisting of an initial 3 min period of unloaded cycling followed by two constant-load work bouts at a work rate corresponding to 90% (V) over dot O-2 peak, separated by 3 min of rest and 3 min of unloaded cycling. (V) over dot O-2 was measured on a breath-by-breath basis, and the response curves were analysed by a biexponential model. To increase signal-to-noise ratio, subjects performed four repetitions of the exercise protocol, each separated by at least one day. There was no significant alteration in (V) over dot O-2 kinetic parameters of the primary, fast component after high-intensity exercise. However, there was a significant effect of prior high-intensity exercise on the (V) over dot O-2 kinetic parameters of the slow component. The time constant and the amplitude of the slow component were reduced by respectively 44% (from 231.0 +/- 111.7 s to 130.1 +/- 50.4s) and 49% (from 824 +/- 270ml.min(-1) to 417 +/- 134 mi min(-1)). The results of this study indicate that the effect of high-intensity exercise on the (V) over dot O-2 kinetics of a subsequent high-intensity exercise is probably limited to an effect on the slow component.