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

Aim. The aim of this study was to compare the oxygen uptake (V̇O 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 V̇O2, running speed associated with the peak V̇O2 (Vpeak), running speed at the lactic threshold and the V̇O2 fraction elicited at the lactic threshold. Methods. Fourteen male endurance-trained runners underwent several 6-min bouts of level (LTR) and 10.5% uphill treadmill running. V̇O2 SC was calculated as the difference between mean V̇O2 during the 6th and the 3rd minutes. Results. The highest mean values for the SC were 181.9±240.2 mL·mur-1 for level running at ∼94% peak V̇O2 and 105.4±154.6 mL·min-1 for uphill running at ∼90% peak V̇O2. The SC observed during the last bout of the LTR correlated with peak V̇O2 and with Vpeak (-0.71 and -0.76, P<0.05, respectively). Conclusion. 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 endurancetrained runners the SC does not correlate with indicators of aerobic fitness.