title: Physical activity in the United States measured by accelerometer.
abstract: OBJECTIVE
  To describe physical activity levels of children (6-11 yr), adolescents (12-19 yr), and adults (20+ yr), using objective data obtained with accelerometers from a representative sample of the U.S. population.
  
  
  METHODS
  These results were obtained from the 2003-2004 National Health and Nutritional Examination Survey (NHANES), a cross-sectional study of a complex, multistage probability sample of the civilian, noninstitutionalized U.S. population in the United States. Data are described from 6329 participants who provided at least 1 d of accelerometer data and from 4867 participants who provided four or more days of accelerometer data.
  
  
  RESULTS
  Males are more physically active than females. Physical activity declines dramatically across age groups between childhood and adolescence and continues to decline with age. For example, 42% of children ages 6-11 yr obtain the recommended 60 min x d(-1) of physical activity, whereas only 8% of adolescents achieve this goal. Among adults, adherence to the recommendation to obtain 30 min x d(-1) of physical activity is less than 5%.
  
  
  CONCLUSIONS
  Objective and subjective measures of physical activity give qualitatively similar results regarding gender and age patterns of activity. However, adherence to physical activity recommendations according to accelerometer-measured activity is substantially lower than according to self-report. Great care must be taken when interpreting self-reported physical activity in clinical practice, public health program design and evaluation, and epidemiological research.
authors: National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA. troianor@mail.nih.gov
authors: Richard P
authors: RP
authors: Troiano
authors: David
authors: D
authors: Berrigan
authors: Kevin W
authors: KW
authors: Dodd
authors: Louise C
authors: LC
authors: Mâsse
authors: Timothy
authors: T
authors: Tilert
authors: Margaret
authors: M
authors: McDowell
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001294:Attitude to Health; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D015438:Health Behavior; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009749:Nutrition Surveys; D015995:Prevalence; D036301:Qualitative Research; D014481:United States