The purpose of this study was to compare sex-related responses to a self-paced all out high-intensity intermittent exercise (HIIE). 9 women and 10 men were submitted to a maximal incremental test (to determine maximum aerobic power - MAP and VO_2peak), and an HIIE cycling (60x8s:12s, effort:pause). During the protocol the mean value of V̇O₂ and heart rate for the entire exercise (VO_{2total and} HR_total) as well as the values only in the effort or pause (V̇O_2effort, VO_2pause and HR_effort and HR_pause) relative to VO_2peak were measured_. Anaerobic power reserve (APR), blood lactate [La] and the respiratory exchange ratio (RER) were also measured. These variables were compared between men and women using the unpaired t test. Men used greater APR (109 ± 12%MAP vs 92 ± 6%MAP) with similar V̇O_2total (74 ± 7 vs 78 ± 8% VO_2peak), however, when effort and pause were analysed separately, V̇O_2effort (80 ± 9 vs 80 ± 5%VO_2peak) was similar between sexes, while V̇O_2pause was lower in men (69 ± 6% vs 77 ± 11% VO_2peak, respectively). Women presented lower power decrement (30 ± 11 vs 11 ± 3%), RER (1.04 ± 0.03 vs 1.00 ± 0.02) and [La]_peak (8.6 ± 0.9 vs 5.9 ± 2.3 mmol.L^-1). Thus, we can conclude that men self-paced HIIE at higher APR but with the same cardiovascular/aerobic solicitation as women.

• Men self-paced high-intensity intermittent exercise at higher intensities than women.

• Men utilized greater anaerobic power reserve than women.

• Men and women had same cardiovascular solicitation.