1. ^*Center for Human Nutrition, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
2. ^†Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina
3. ^**Department of Exercise and Sport Sciences, University of North Carolina, Chapel Hill, North Carolina
4. ^‡Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, Pennsylvania
5. ^§Department of Exercise Science, University of South Carolina, Columbia, South Carolina
6. ^¶Graduate School of Public Health, San Diego State University, San Diego, California
7. ^††Department of Physiology, University of Arizona, Tucson, Arizona
8. ^‡‡National Heart, Lung, and Blood Institute, Bethesda, Maryland
9. ^§§Department of Biostatistics, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana

Correspondence: Margarita S. Treuth Center for Human Nutrition, The Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205. E-mail: mtreuth@jhsph.edu

^*The costs of publication of this article were defrayed, in part, by the payment of page charges. This article must, therefore, be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

Received 31 March 2006; Revised  0000; Accepted 5 January 2007.

Abstract

Objective: To describe the patterns (specifically comparing weekdays and weekends classified by intensities) of physical activity (PA) measured by accelerometry in adolescent girls.

Research Methods and Procedures: Healthy sixth grade girls (n = 1603), 11 to 12 years old, were randomly recruited from 36 schools participating in the Trial of Activity in Adolescent Girls. Age, ethnicity, socioeconomic status, weight, and height were taken. PA patterns were measured for 6 days using accelerometry.

Results: Adolescent girls spend most of their time in sedentary (52% to 57% of the day) and light activity (40% to 45% of the day) on weekdays and weekends. In all girls, total PA comprised 44.5% of the day (41.7% light, 2.2% moderate, and 0.7% vigorous) with sedentary activity comprising 55.4% . Moderate-to-vigorous PA (MVPA) was higher (p < 0.001) on weekdays than weekends in all girls, but MVPA was lower in at-risk of overweight + overweight girls (p < 0.001) on both weekdays and weekends compared with normal-weight girls.

Discussion: Adolescent girls are more active at moderate and vigorous intensities on weekdays than on weekends, and at-risk of overweight and those overweight spend less time engaging in MVPA than normal-weight girls.