Drift in Oxygen Consumption during Prolonged Sub-maximal Exercise in Subjects of Different Training Status

Abstract

This study investigated whether the drift in oxygen consumption ( _VO 2 drift) during prolonged cycling exercise at the lactate threshold (LT) is smaller in endurance-trained subjects than in sedentary subjects, and whether the change in muscle activity assessed using electromyography (EMG) during prolonged exercise is aŠected by training status and corresponds with _VO 2 drift. Seven sedentary (mean(SD), _VO 2 max, 41.8(5.9) ml･kg･min -1 ) and eight endurance-trained men ( _VO 2 max, 58.7(5.4) ml･kg･min -1 ) performed prolonged cycling exercise for 70 min at the LT. During the prolonged exercises, _VO 2 , _VCO 2 , and the electrical activity of four muscles (vastus lateralis, vastus medialis, biceps femoris, and gastrocnemius medialis) were measured continuously. During 70 min exercise at the LT, the absolute _VO 2 drift in endurance-trained group was higher than sedentary group (469(189) ml vs 309(77) ml, respectively), whereas the relative _VO 2 drift was not diŠered between the sedentary and endurance-trained groups (1.20(0.04) times vs 1.21(0.08) times, respectively). Additionally, RMS and iEMG did not change during prolonged exercise. These results suggest that the relative _VO 2 drift during 70 min exercise at the LT was not diŠered between with the subject groups with the diŠerent training status and endurance capacity. The _VO 2 drift during 70 min exercise at the LT did not correspond with the changes in muscle activity of leg muscles, EMGs of which did not change throughout the experiments.

Dose effects of New Zealand blackcurrant on substrate oxidation and physiological responses during prolonged cycling

“…Similarly, the time effect for V̇O2 would explain the time effect for relative intensity and cycling economy and is likely to result from V̇O2 drift caused by an increase in body temperature, recruitment of additional muscle fibres and fat oxidation (Ishijima et al 2011).…”