Age-related change in physical activity in adolescent girls

J Adolesc Health. 2009 Mar;44(3):275-82. doi: 10.1016/j.jadohealth.2008.07.003. Epub 2008 Oct 29.


Purpose: To determine the annual rate at which physical activity changes in girls during middle school using both objective and self-report measures of physical activity.

Methods: Participants were sixth- and eighth-grade girls from the control schools in the Trial of Activity for Adolescent Girls (TAAG). Random cross-sectional samples initially were drawn from sixth-grade girls (n=786) and 2 years later from eighth-grade girls (n=1545). A cohort of 501 girls was in both the sixth- and the eighth-grade samples. The girls wore an accelerometer for 6 days and completed the 3-Day Physical Activity Recall. Data were summarized using 3.0-, 4.6-, and 6.5-metabolic equivalent cutpoints for accelerometry and self-reported physical activity. Analyses were performed using repeated-measures analysis of variance in PROC MIXED.

Results: More than 40% of the girls were white, approximately 20% were African American, and 20% were Hispanic. The annual percent decrease in physical activity in the cross-sectional sample was approximately 4% (-1.76 min moderate-to-vigorous physical activity/day), using accelerometer data. The percent decrease in physical activity based on self-report data was higher, 6% to 13%, depending on the physical activity variable. Declines tended to be larger in African American girls, but the ethnic differences were not statistically significant.

Conclusions: Based on comparisons of cross-sectional samples of sixth- and eighth-grade girls, objectively measured physical activity declined at a rate of 4% per year.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Age Factors
  • Body Mass Index
  • Cross-Sectional Studies
  • Exercise*
  • Female
  • Humans
  • Monitoring, Physiologic / instrumentation
  • Self Disclosure
  • United States