Increases in V˙O2max exhibited in response to different HIIT regimes are due to improvements in oxygen delivery.

No abstract

Data revealed significant (p < 0.001) improvements in VO2max in LO (22.3 ± 6.9 %) and HI (21.9 ± 11.6 %) that were similar (p > 0.05) between groups. Approximately 60 % of the increase in VO2max in HI was observed in the initial 3 weeks, compared to only 20 % in LO. No change (p > 0.05) in body weight or body composition was revealed in response to training. Results demonstrate that a relatively prolonged regimen of moderate or more intense interval training induces similar improvements in cardiorespiratory fitness, although HI induced greater increases in VO2max early on in training than LO. Completion of more intense interval training may be an effective means to expedite increases in VO2max soon after initiation of exercise training.