The effect of inspired oxygen fraction on peak oxygen uptake during arm exercise

It has been shown that peak oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{V}}$$ \end{document}O2peak) during leg exercise is enhanced by an increased inspiratory oxygen fraction (FiO2), indicating that oxygen supply is the limiting factor. Whether oxygen supply is a limiting factor in arm exercise performance is unknown. The purpose of this study, therefore, was to examine the effect of different levels of FiO2 on \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{V}}$$ \end{document}O2peak during arm exercise in healthy individuals. Nine men successfully performed three incremental arm-cranking exercise tests with FiO215%, FiO221% and FiO250% applied in counterbalanced order. A significant FiO2 dependency was observed for \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{V}}$$ \end{document}O2peak (p=0.02) and power output (p=0.03) and post hoc tests revealed a significant difference in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{V}}$$ \end{document}O2peak between 15 and 50% FiO2 (p=0.02), but not between 15 and 21% FiO2, and 21 and 50% FiO2. The results of this study show that \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{V}}$$ \end{document}O2peak is enhanced with increasing FiO2, and suggest that \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\dot{V}}$$ \end{document}O2peak during arm exercise is limited by oxygen supply rather than by the metabolic machinery within the muscle itself.