School-Day and Overall Physical Activity Among Youth

In an effort to curb childhood obesity, policy and programs aimed at increasing school-day physical activity are often implemented. These strategies, however, may not increase total physical activity if youth compensate by reducing physical activity outside of school. This study tested whether higher school-day physical activity is associated with higher overall daily physical activity among youth.

Using accelerometer data from the National Health and Nutrition Examination Surveys (NHANES) conducted in 2003-2004 and 2005-2006, researchers estimated physical activity levels during the school day (8am-3pm) among youth aged 6-19 years. Analyses were conducted in 2012.

Key Findings:

  • The 2,548 participants provided an average of 5.7 days of valid monitor data and 14.0 hours of average daily monitor wear time.
  • Physical activity declined significantly as children transitioned into adolescence, as other studies have also found.
  • Controlling for covariates, each additional minute of school-day moderate-to-vigorous physical activity (MVPA) was associated with an additional 1.14 minutes of total daily MVPA, or 0.14 additional minutes outside the school day.

Limitations to this study include the use of a waist-mounted accelerometer and the lack of a measure of urbanicity. This nationally representative, objectively measured study of physical activity among youth shows that school-based physical activity can play an important role in increasing youth’s overall physical activity.