Slow component of VO2 during level and uphill treadmill running : relationship to aerobic fitness in endurance runners

The aim of this study was to compare the oxygen uptake (VO^sub 2^) slow component (SC) during level and uphill running in endurance runners, and to identify associations between the SC and the following aerobic fitness indicators: peak VO^sub 2^, running speed associated with the peak VO^sub 2^ (Vpeak), running speed at the lactic threshold and the VO^sub 2^ fraction elicited at the lactic threshold. Fourteen male endurance-trained runners underwent several 6-min bouts of level (LTR) and 10.5% uphill treadmill running. VO^sub 2^ SC was calculated as the difference between mean VO^sub 2^ during the 6th and the 3rd minutes. The highest mean values for the SC were 181.9±240.2 mL*min^sup -1^ for level running at ~94% peak VO^sub 2^ and 105.4±154.6 mL*min^sup -1^ for uphill running at ~90% peak VO^sub 2^. The SC observed during the last bout of the LTR correlated with peak VO^sub 2^ and with Vpeak (-0.71 and -0.76, P<0.05, respectively). The results show that for endurance-trained runners the magnitude of the SC is not affected by the treadmill gradient and that within a homogeneous sample of endurance-trained runners the SC does not correlate with indicators of aerobic fitness.