LAUSR

Step test protocols are typically based on the heart rate (HR) measured either during exercise or during recovery. This study developed a new step test protocol to estimate maximal oxygen consumption (V˙O2max\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}$$\end{document}) based on HRs measured during and after exercise, assessed the criterion validity of the model, and evaluated the protocol’s test–retest reliability. The protocol estimates V˙O2max\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}$$\end{document} from HR measurements made once a minute during 3 min of step exercise and 2 min of recovery. The model was derived using a group of 118 working adults and cross-validated using a second group of 74 working adults. Furthermore, V˙O2max\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}$$\end{document} was measured using a conventional treadmill test. While multiple regression analyses were used to develop prediction equations for V˙O2max\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}$$\end{document}, intraclass correlation coefficients (ICCs) were used to examine test–retest reliability. HRs during and after exercise significantly correlated with the measured V˙O2max\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}$$\end{document}. The highest correlation (r = − 0.61) was for an HR index that combined values of HRs during and after exercise. A model including age, sex, body mass index, and the HR index accounted for 60% of the variance in measured V˙O2max\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}$$\end{document} (standard error of the estimate, 4.05 mL kg−1 min−1 or 10.5%). Cross-validation analyses demonstrated good stability of the V˙O2max\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}$$\end{document} prediction models. The ICC for the HR index was 0.65 (0.53–0.74), indicating fair to good reliability. The HR index, based on a combination of HR measurements during and after stepping exercise, offers a validated V˙O2max\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\text{{V}}}{{\text{O}}}_{\text{2max}}$$\end{document} estimation procedure suitable for use in the workplace.