Measures of cardiorespiratory fitness in relation to measures of body size and composition among children

Clin Physiol Funct Imaging. 2015 Nov;35(6):469-77. doi: 10.1111/cpf.12185. Epub 2014 Aug 27.

Abstract

Background: In the exercise testing measures of cardiorespiratory fitness need to be scaled by body size or composition to enable comparison between individuals. Traditionally used weight-proportional measures are potentially confounded by body adiposity that hampers their interpretation and applicability in the clinical assessment of cardiorespiratory fitness.

Objective: We aimed to find the most appropriate measure of body size or composition for scaling of measures of cardiorespiratory fitness among children.

Methods: We assessed body weight and height, maximal workload (W MAX ) and maximal oxygen uptake (VO2 MAX ) using cycle ergometer exercise test with respiratory gas analysis and body lean mass (LM) and fat mass (FM) by dual-energy X-ray absorptiometry and by bioimpedance analysis among 38 children. The data were analysed using Pearson's coefficients for correlation and stepwise linear regression models.

Results: Lean mass (r > 0.54) and height (r > 0.51) had stronger positive correlations with absolute W MAX and VO2 MAX than weight (r > 0.30) in girls and boys. None of the measures of body size or composition correlated with LM-proportional W MAX or VO2 MAX in girls or boys. Only LM correlated positively with height-proportional W MAX (r = 0.65) and VO2 MAX (r = 0.71) in boys. FM correlated negatively with weight-proportional W MAX (r < -0.58) and VO2 MAX (r < -0.64) in girls and boys. FM was even stronger determinant of weight-proportional W MAX (β = -0.68) and VO2 MAX (β = -0.61) than exercise performance in multivariate linear regression models.

Conclusions: While assessing cardiorespiratory fitness, LM is the most appropriate measure of body size or composition for scaling of W MAX and VO2 MAX, because scaling by body weight introduces confounding by body adiposity.

Keywords: adiposity; ergometer; exercise testing; lean mass; maximal oxygen uptake; maximal workload.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms*
  • Anthropometry / methods*
  • Body Composition / physiology*
  • Body Size / physiology*
  • Child
  • Child Health*
  • Exercise Test / methods*
  • Female
  • Humans
  • Male
  • Physical Fitness
  • Reproducibility of Results
  • Sensitivity and Specificity