Determination of the maximal fat oxidation point in obese children and adolescents: validity of methods to assess maximal aerobic power

We aimed to examine the interchangeability of techniques used to assess maximal oxygen consumption (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}_{2\text{max}}}$$\end{document}) and maximal aerobic power (MAP) employed to express the maximal fat oxidation point in obese children and adolescents. Rate of fat oxidation were measured in 24 obese subjects (13.0 ± 2.4 years; Body Mass Index 30.2 ± 6.3 kg m−2) who performed a five 4-min stages submaximal incremental cycling exercise. A second cycling exercise was performed to measure \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}_{2\text{max}}}$$\end{document}. Results are those of the 20 children who achieved the criterion of RER (>1.02) to assess the attainment of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}_{2\text{max}}}$$\end{document}. Although correlations between results obtained by different methods were strong, Bland–Altman plots showed little agreement between the maximal fat oxidation point expressed as a percentage of measured \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}_{2\text{max}}}$$\end{document} and as % \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}_{2\text{max}}}$$\end{document} estimated according to ACSM guidelines (underestimation : −5.9%) or using the predictive equations of Wasserman (−13.9%). Despite a mean underestimation of 1.4% several values were out of the limits of agreement when comparing measured MAP and Theoretical MAP. Estimations of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ifmmode\expandafter\dot\else\expandafter\.\fi{V}{\text{O}_{2\text{max}}}$$\end{document} lead to underestimations of the maximal fat oxidation point.