Effect of high-intensity interval training and detraining on extra {\dot{{V}}\hbox{O}_{2}} and on the {\dot{{V}}\hbox{O}_{2}} slow component

To examine the effect of 6-week of high-intensity interval training (HIT) and of 6-week of detraining on the \({\dot{{V}}\hbox{O}_{2}}\)/Work Rate (WR) relationship and on the slow component of \({\dot{{V}}\hbox{O}_{2},}\) nine young male adults performed on cycle ergometer, before, after training and after detraining, an incremental exercise (IE), and a 6-min constant work rate exercise (CWRE) above the first ventilatory threshold (VT1). For each IE, the slope and the intercept of the \({\dot{{V}}\hbox{O}_{2}}\)/WR relationship were calculated with linear regression using data before VT1. The difference between \({\dot{{V}}\hbox{O}_{{\rm 2max}}}\) measured and \({\dot{{V}}\hbox{O}_{{\rm 2max}}}\) expected using the pre-VT1 slope was calculated (extra \({\dot{{V}}\hbox{O}_{2}}\)). The difference between \({\dot{{V}}\hbox{O}_{2}}\) at 6th min and \({\dot{{V}}\hbox{O}_{2}}\) at 3rd min during CWRE \({(\Delta\dot{{V}}\hbox{O}_{2(6^{\prime}-3^{\prime})})}\) was also determined. HIT induced significant improvement of most of the aerobic fitness parameters while most of these parameters returned to their pre-training level after detraining. Extra \({\dot{{V}}\hbox{O}_{2}}\) during IE was reduced after training (130 ± 100 vs. −29 ± 175 ml min−1, P = 0.04) and was not altered after detraining compared to post-training. \({\Delta\dot{{V}}\hbox{O}_{2(6^{\prime}-3^{\prime})}}\) during CWRE was unchanged by training and by detraining. We found a significant correlation (r 2 = 0.575, P = 0.02) between extra \({\dot{{V}}\hbox{O}_{2}}\) and \({\Delta\dot{{V}}\hbox{O}_{2(6^{\prime}-3^{\prime})}}\) before training. These results show that an alteration of extra \({\dot{{V}}\hbox{O}_{2}}\) can occur without any change in the \({\dot{{V}}\hbox{O}_{2}}\) slow component, suggesting a possible dissociation of the two phenomena. Moreover, the fact that extra \({\dot{{V}}\hbox{O}_{2}}\) did not change after detraining could indicate that this improvement may remain after the loss of other adaptations.