title: Adiposity is related to decrements in cardiorespiratory fitness in obese and normal-weight children.
abstract: BACKGROUND
  Obese children are typically less physically active than their normal-weight peers and are often assumed to be 'unfit'.
  
  
  OBJECTIVE
  Investigate the relationships between adiposity, physical activity levels and cardiorespiratory fitness (CRF) in obese and normal-weight children. A secondary aim was to examine obese/normal-weight differences in CRF.
  
  
  METHODS
  Obese (N = 107) and normal-weight (N = 132) 10-13-year-olds participated. Fat-free mass (FFM), percent fat, physical activity and peak oxygen uptake (VO2peak ) were assessed. Analyses were adjusted for socioeconomic status (SES).
  
  
  RESULTS
  Higher percent fat was inversely associated with VO2peak normalized for mass (r = -0.780, P < 0.001) even after controlling for physical activity (r = -0.673, P < 0.001). While higher percent fat was also inversely associated with VO2peak normalized for FFM, this was only significant in males (r = -0.247, P = 0.004) and did not persist after controlling for physical activity (r = -0.059 P = 0.526). Compared with normal-weight children, obese children had higher absolute VO2peak , lower VO2peak corrected for mass (P ≤ 0.009) and lower VO2peak corrected for FFM (P = 0.041) that did not persist after controlling for SES (P = 0.086).
  
  
  CONCLUSIONS
  Obesity-related inefficiencies in CRF were evident. Higher adiposity was associated with poorer CRF relative to mass, irrespective of physical activity levels. However, low physical activity levels may be responsible for associations between adiposity and CRF relative to FFM seen in boys, indicating the importance of encouraging physical activity.
authors.affiliation: Alliance for Research in Exercise, Nutrition and Activity, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia.
authors.forename: M D
authors.initials: MD
authors.lastname: Tsiros
authors.affiliation: Alliance for Research in Exercise, Nutrition and Activity, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia.
authors.forename: A M
authors.initials: AM
authors.lastname: Coates
authors.affiliation: Alliance for Research in Exercise, Nutrition and Activity, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia.|School of Biomedical Sciences & Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.
authors.forename: P R C
authors.initials: PR
authors.lastname: Howe
authors.affiliation: RMIT University, School of Health Sciences, Bundoora, Victoria, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Walkley
authors.affiliation: Mater Mothers' Hospital, Mater Research Institute, University of Queensland, South Brisbane, Queensland, Australia.
authors.forename: A P
authors.initials: AP
authors.lastname: Hills
authors.affiliation: School of Exercise and Nutrition Sciences, Queensland University of Technology, Kelvin Grove, Queensland, Australia.
authors.forename: R E
authors.initials: RE
authors.lastname: Wood
authors.affiliation: Alliance for Research in Exercise, Nutrition and Activity, Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia.
authors.forename: J D
authors.initials: JD
authors.lastname: Buckley
mesh_terms: D050154:Adiposity; D001315:Australia / Q000453:epidemiology; D015992:Body Mass Index; D002320:Cardiovascular Physiological Phenomena; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D063766:Pediatric Obesity / Q000150:complications / Q000503:physiopathology*; D010809:Physical Fitness; D012143:Respiratory Physiological Phenomena; D055105:Waist Circumference
keywords: Body mass index; child; cycle ergometry; peak oxygen uptake