Excess post-exercise oxygen consumption following HIIT between males and females across the menstrual cycle

BACKGROUND: Recovery from high-intensity exercise is critical to solidify increases in fitness and to prepare the body for the next exercise session. However, most research on exercise recovery focuses on males, and it is unclear how relevant recovery recommendations may be to females throughout their menstrual cycle. PURPOSE: To characterize differences in excess post-exercise oxygen consumption (EPOC) following high intensity interval training (HIIT) between males and females at 3 phases of the menstrual cycle. METHODS: Twenty two physically active adults (12 male, 10 female; age: 20.2 ± 1.6 yrs; BMI 25 ± 2.7 kg/m 2 ) completed a preliminary treadmill test of maximal oxygen consumption (VO 2 ) followed by 1 or 3 sessions of HIIT on a treadmill. Female participants reported consistent menstrual cycles (MC) and no contraceptive use. Female participants completed HIIT sessions during the early follicular (EF), late follicular (LF), and mid-luteal (ML) phases of their MC, while male participants completed one HIIT session. Heart rate (HR), VO 2 , and respiratory exchange ratio (RER) were analyzed for a 20 minute seated period following exercise. EPOC measurements were compared across menstrual cycle phases using repeated measures ANOVAs and between males and females using one-way ANOVAs. RESULTS: There were no significant differences in HR or RER between sexes or menstrual cycle phases during acute exercise recovery (p > 0.05). In post hoc analysis, recovery VO 2 was not significantly different between sexes except for 3 of the 20 measured post-exercise time points (12 min, 13 min, and 20 min). VO 2 had no significant interaction between MC phases over recovery time (F38,342=0.82; p=0.77; eta2 = 0.08). CONCLUSION: Menstrual cycle phase did not affect cardiovascular or metabolic recovery from HIIT exercise. More robust research is needed on sex differences during EPOC. It may not be necessary to control for menstrual cycle phase when conducting exercise recovery research with female participants. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.