title: Objectively measured physical activity and fat mass in a large cohort of children.
abstract: BACKGROUND
  Previous studies have been unable to characterise the association between physical activity and obesity, possibly because most relied on inaccurate measures of physical activity and obesity.
  
  
  RESULTS
  We carried out a cross sectional analysis on 5,500 12-year-old children enrolled in the Avon Longitudinal Study of Parents and Children. Total physical activity and minutes of moderate and vigorous physical activity (MVPA) were measured using the Actigraph accelerometer. Fat mass and obesity (defined as the top decile of fat mass) were measured using the Lunar Prodigy dual x-ray emission absorptiometry scanner. We found strong negative associations between MVPA and fat mass that were unaltered after adjustment for total physical activity. We found a strong negative dose-response association between MVPA and obesity. The odds ratio for obesity in adjusted models between top and the bottom quintiles of minutes of MVPA was 0.03 (95% confidence interval [CI] 0.01-0.13, p-value for trend <0.0001) in boys and 0.36 (95% CI 0.17-0.74, p-value for trend = 0.006) in girls.
  
  
  CONCLUSIONS
  We demonstrated a strong graded inverse association between physical activity and obesity that was stronger in boys. Our data suggest that higher intensity physical activity may be more important than total activity.
authors: Department of Oral and Dental Science, University of Bristol, United Kingdom. Andy.Ness@bristol.ac.uk
authors: Andy R
authors: AR
authors: Ness
authors: Sam D
authors: SD
authors: Leary
authors: Calum
authors: C
authors: Mattocks
authors: Steven N
authors: SN
authors: Blair
authors: John J
authors: JJ
authors: Reilly
authors: Jonathan
authors: J
authors: Wells
authors: Sue
authors: S
authors: Ingle
authors: Kate
authors: K
authors: Tilling
authors: George Davey
authors: GD
authors: Smith
authors: Chris
authors: C
authors: Riddoch
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000473:pathology; D001823:Body Composition; D015992:Body Mass Index; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods; D009043:Motor Activity / Q000502:physiology; D009765:Obesity / Q000473:pathology*