Figure 3.

Respiratory gases during an incremental test. Running similarly increased general O₂ consumption ($\dot{\mathrm{V}}$O₂, A,B) and CO₂ production ($\dot{\mathrm{V}}$CO₂, E,F) in males and females at different speeds up to 33 m/min. $\dot{\mathrm{V}}$O_2max was similar between the sexes (C) total $\dot{\mathrm{V}}$O₂ (D) and $\dot{\mathrm{V}}$CO₂ (G) was only higher in males due to higher running speeds. Proestrus increased submaximal $\dot{\mathrm{V}}$O₂ (B and D) and $\dot{\mathrm{V}}$CO₂ (G) at lighter intensities of ergospirometry (30–35% $\dot{\mathrm{V}}$O_2max). Values are expressed as mean ± standard error of mean (SEM). N = 8–10 animals/group. *P < 0.05 vs. male, ^#P < 0.05 vs. females (ANOVA, Bonferroni post hoc test).