O2 uptake and muscle deoxygenation kinetics during the transition to moderate-intensity exercise in different phases of the menstrual cycle in young adult females

O2 uptake \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\dot{V}O_{2})$$\end{document} kinetics were examined during the follicular (F) and luteal (L) phases of the menstrual cycle to determine if there was an effect of altered sex hormones on the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2}$$\end{document} response to moderate-intensity exercise. Seven healthy women (age 21 ± 2 years; mean ± SD) performed six transitions from 20 W to moderate-intensity exercise (∼ 90 % \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hat{\theta}_{{{\rm L}}}$$\end{document}) during the F and L phase. \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2}$$\end{document} was measured breath-by-breath and deoxyhemoglobin/myoglobin (Δ HHb) was determined by near infrared spectroscopy. Progesterone and estrogen were significantly (P < 0.05) elevated during the L compared to F phase. \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2}$$\end{document} kinetics \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\tau \dot{V}O_{2})$$\end{document} were not different in the two phases of the menstrual cycle (F, 22 ± 5 s; L, 22 ±  6 s; 95% confidence intervals ±4 s) nor was the time course of the Δ HHb response (F, TD 11 ± 2 s, τ 11 ± 3 s; L, TD 12 ± 2 s, τ 12 ± 11 s; τHHb 95% confidence intervals ±3 s). Respiratory exchange ratio (RER) was not different between phases for baseline or steady-state exercise and the blood lactate response to exercise was not different. In conclusion, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2}$$\end{document} kinetics at the onset of moderate-intensity exercise are not affected by the phase of the menstrual cycle in young females suggesting either no change in, or no effect of metabolic activation on the on-transient kinetics of moderate-intensity exercise. Additionally, the similar adaptation of Δ HHb in combination with unchanged \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2}$$\end{document} suggests that there were no differences in the adaptation of local muscle O2 delivery.