Physical activity in the United States measured by accelerometer.
Level 4 - case-series / case-control
Cross-sectional survey of a representative population sample
PubMed 18091006 · doi:10.1249/mss.0b013e31815a51b3
What was done
Analyzed physical activity using objective accelerometer data from the 2003–2004 National Health and Nutrition Examination Survey (NHANES), a nationally representative sample of the civilian, noninstitutionalized US population. Activity was assessed across children (6–11 years), adolescents (12–19 years), and adults (20+ years) in 6,329 participants with at least 1 day of accelerometer wear and 4,867 participants with 4 or more days.
What was found
Males were more active than females across age groups. Physical activity declined steeply from childhood to adolescence and continued to decrease with age. Specifically, 42% of children (ages 6–11) achieved the recommended 60 min/day of activity, compared with 8% of adolescents (ages 12–19). Among adults (age 20+), fewer than 5% met the guideline of 30 min/day. Accelerometer-measured adherence to physical activity guidelines was substantially lower than rates typically derived from self-report.
Why it matters
This study established the first objective, nationally representative benchmark of physical activity in the United States, showing that actual physical activity levels are drastically lower than self-reported estimates suggest.
Limits
The cross-sectional design cannot establish individual longitudinal trajectories. Compliance dropped from 6,329 participants with 1 day of data to 4,867 participants with 4 or more days, and specific accelerometer intensity thresholds or activity types were not detailed in the abstract.
Cited by
- supports The average American gets less than 20 minutes of physical activity per day.