Time Spent Near Maximal Oxygen Uptake During Exercise at Different Regions of the Severe-Intensity Domain.

Faricier, R, Fleitas-Paniagua, PR, Iannetta, D, Millet, GY, Keir, DA, and Murias, JM. Time spent near maximal oxygen uptake during exercise at different regions of the severe-intensity domain. J Strength Cond Res 39(2): e106-e114, 2025-This study applied the critical power (CP) model and several bouts of constant-power exercise within different regions of the severe-intensity domain to determine whether there exists an optimal intensity to maximize time spent near V̇ o2 peak. Subjects visited the laboratory 9 times. After a ramp-incremental test to determine V̇ o2 peak and peak power output (PO peak ), 9 active individuals (5 females) performed 4 constant-power bouts to task failure between 65 and 100%PO peak to estimate CP and total finite work above CP (W'). Subjects then completed 4 additional exhaustive trials predicted to result in task failure in ∼3, 6, 9, and 12 minutes. Time spent at V̇ o2 peak was calculated as the duration at which V̇ o2 ≥ 95% of the trial-specific V̇ o2 peak. The level of significance set for the study was p < 0.05. Mean CP and W' were 201 ± 48 W and 17.6 ± 8.4 kJ, respectively. For each bout, time to task failure was 2.7 ± 0.5, 6.3 ± 0.6, 9.5 ± 1.2, and 13.1 ± 3.1 minutes for the 3-, 6-, 9-, and 12-minute conditions. Time spent at V̇ o2 peak during the 3-minute trial (45 ± 22 seconds) was shorter than during the 9-minute (204 ± 104 seconds; p = 0.002) and 12-minute trials (260 ± 155 seconds; p < 0.001). The 6-minute trial (117 ± 46 seconds) had shorter ( p = 0.005) time spent at V̇ o2 peak compared with the 12-minute trial. At least when performing single bouts of exercise, intensities closer to CP (i.e., those sustainable for ∼9 minutes or longer) seem preferable compared with POs in the upper regions of the severe-intensity domain to maximize time at V̇ o2 peak.