Study objectives: To examine the effects of 6 weeks of exercise training above or below the lactate threshold (LT) on the slow component (SC) of pulmonary oxygen consumption (V̇o2).
Design: Randomized controlled trial.
Setting: University human performance laboratory.
Participants: Apparently healthy, untrained men (n = 18).
Interventions: Subjects were randomized to one of three groups: high-intensity exercise training (HI) [above the LT], moderate-intensity exercise training (MOD) [below the LT], or no exercise training (CON). Exercise groups performed cycle ergometry 4 d/wk for 6 weeks. Total work throughout training was constant between groups.
Measurements and results. Maximal cycle ergometry was performed at baseline and after training to assess power output at the LT (WLT), V̇o2 at the LT (V̇o2LT), and peak V̇o2 (V̇o2PK). High-intensity, constant-load cycling was performed at baseline and weeks 1, 2, 4, and 6 to assess SC adaptations. WLT, V̇o2LT, and V̇o2PK increased after 6 weeks in both exercise groups compared to the CON group (p < 0.05), although there were no differences between the training groups. SC of V̇o2 decreased 44% in the HI group following 1 week of exercise training vs MOD (20%, p < 0.05) and CON (12%, p < 0.01) groups. The SC attenuation was more prominent at all time points in the HI group compared to the MOD group. Total SC attenuation over the 6-week training period did not differ between the HI (71%) and MOD (57%) groups.
Conclusions: Training at HI or MOD produced similar improvements in the LT, V̇o2, and power output at peak exertion when total work output was held constant. Attenuation of the SC with training above and below the LT were similar, although above-LT training promoted faster SC adaptations.