title: Measures of cardiorespiratory fitness in relation to measures of body size and composition among children.
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.
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland.|Institute of Biomedicine/Physiology, University of Eastern Finland, Kuopio, Finland.
authors.forename: Tuomo
authors.initials: T
authors.lastname: Tompuri
authors.affiliation: Institute of Biomedicine/Physiology, University of Eastern Finland, Kuopio, Finland.
authors.forename: Niina
authors.initials: N
authors.lastname: Lintu
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland.|Kuopio Research Institute of Exercise Medicine, Kuopio, Finland.
authors.forename: Kai
authors.initials: K
authors.lastname: Savonen
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland.
authors.forename: Tomi
authors.initials: T
authors.lastname: Laitinen
authors.affiliation: Department of Internal Medicine, Kuopio University Hospital, Kuopio, Finland.
authors.forename: David
authors.initials: D
authors.lastname: Laaksonen
authors.affiliation: Department of Pediatrics, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland.
authors.forename: Jarmo
authors.initials: J
authors.lastname: Jääskeläinen
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland.|Institute of Biomedicine/Physiology, University of Eastern Finland, Kuopio, Finland.|Kuopio Research Institute of Exercise Medicine, Kuopio, Finland.
authors.forename: Timo A
authors.initials: TA
authors.lastname: Lakka
mesh_terms: D000465:Algorithms; D000886:Anthropometry / Q000379:methods*; D001823:Body Composition / Q000502:physiology*; D049628:Body Size / Q000502:physiology*; D002648:Child; D000067576:Child Health; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D010809:Physical Fitness; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: adiposity; ergometer; exercise testing; lean mass; maximal oxygen uptake; maximal workload