Abstract INTRODUCTION: A common low-volume high-intensity interval training (HIIT) protocol involves repeating 1-min near-maximal bouts interspersed with 1-min rest 10 times within a session and has demonstrated greater excess post-exercise oxygen consumption (EPOC) than moderate-intensity continuous training (MICT). While typical MICT protocols (≥30 min) are longer than low-volume HIIT (20 min), yielding greater oxygen consumed (VO2) during exercise, higher-volume HIIT protocols of similar duration to MICT (≥28 min) have been shown to elicit similar during-exercise VO2 while eliciting greater EPOC. PURPOSE: To examine effects of extending the 20-min low-volume HIIT protocol to 30 min (by adding 5 additional exercise bouts) on overall VO2 and post-exercise fat oxidation compared to MICT. METHODS: Nine recreationally active males (age: 22±4 y, V̇O2max: 48.2±7.6 ml⋅kg-1⋅min-1, HRmax: 193±8 bpm) completed four randomized sessions: (1) no-exercise control (CTRL); (2) MICT (30 min at 60% VO2max); (3) low-volume HIIT (10x1-min at 90% HRmax, 1-min rest); and (4) higher-volume HIIT (15x1-min at 90% HRmax, 1-min rest). Between-session differences for overall VO2 and fat oxidation were assessed. RESULTS: V̇O2 during exercise was elevated in all exercise sessions versus CTRL (P0.001). Modified-HIIT and MICT increased fat oxidation post-exercise compared to CTRL (P< 0.015). CONCLUSION: Modifying low-volume HIIT with extra bouts to match MICT duration produces greater responses to exercise metabolism.
Jahanfar et al. (Thu,) studied this question.