title: Relations of moderate and vigorous physical activity to fitness and fatness in adolescents.
abstract: BACKGROUND
  It is unclear how moderate and vigorous intensities of physical activity (PA) are associated with cardiovascular fitness (CVF) and percentage of body fat (%BF) in adolescents.
  
  
  OBJECTIVE
  We tested the hypothesis that vigorous PA, to a greater degree than moderate PA, would be associated with better CVF and lower %BF.
  
  
  METHODS
  This was a cross-sectional study of 421 black and white high school students (x age: 16 y). PA was measured with 5 d of accelerometry and expressed in min/d of moderate or vigorous PA. CVF was measured with a multistage treadmill test and was expressed as the oxygen consumption at a heart rate of 170 bpm. %BF was measured with dual-energy X-ray absorptiometry. Multiple regressions were used to determine the degree to which variance in CVF and %BF was explained by PA, after control for age, sex, race, and the sex x race interaction.
  
  
  RESULTS
  A higher index for CVF was associated with higher amounts of moderate and vigorous PA; more variance was explained by vigorous than by moderate PA. Lower %BF was associated with higher amounts of vigorous PA but not with the amount of moderate PA.
  
  
  CONCLUSIONS
  Black and white adolescents who engaged in relatively large amounts of free-living vigorous exercise were likely to be relatively fit and lean.
authors.affiliation: Georgia Prevention Institute, Department of Pediatrics, Medical College of Georgia, Augusta, GA, USA. bgutin@mcg.edu
authors.forename: Bernard
authors.initials: B
authors.lastname: Gutin
authors.forename: Zenong
authors.initials: Z
authors.lastname: Yin
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Humphries
authors.forename: Paule
authors.initials: P
authors.lastname: Barbeau
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000378:metabolism; D000293:Adolescent; D041923:Adolescent Development / Q000145:classification*; D001823:Body Composition; D003430:Cross-Sectional Studies; D005260:Female; D005845:Georgia; D006801:Humans; D007702:Kinetocardiography / Q000379:methods; D008297:Male; D010809:Physical Fitness; D012044:Regression Analysis