Time Spent Above 90% and 95% of VO2max During Three High-Intensity Interval Cycling Protocols

Maximising time spent at high fractions of maximal oxygen uptake (V̇O2max) is considered an important target of high-intensity interval training (HIIT). This study compared the accumulated time spent at ≥90% and ≥95% of V̇O2max during three work- and effort-matched cycling HIIT protocols. Twelve level 3–4 male cyclists completed Short HIIT (15 × 43.5 s work/43.5 s recovery), Long HIIT (4 × 3 min work/3 min recovery), and decreasing power output HIIT (6 × 114.5 s work/114.5 s recovery) in a randomised crossover design. Pulmonary gas exchange was measured breath-by-breath, and the accumulated time above 90% and 95% of V̇O2max was calculated for each session. Significant differences were observed between protocols for both outcomes. Long HIIT produced greater time above 90% of V̇O2max (580 ± 61.8 s) than decreasing power output HIIT (512 ± 77 s) and short HIIT (422 ± 90 s). A similar pattern was observed above 95% of V̇O2max, with long HIIT (404 ± 126 s) exceeding decreasing power output HIIT (308 ± 131 s) and short HIIT (193 ± 69 s). Peak blood lactate concentrations did not differ between protocols. These findings suggest that, under matched 1:1 work-to-recovery conditions, longer intervals may provide a greater acute near-maximal aerobic stimulus than shorter intervals.