Original article
Patterns and Determinants of Physical Activity in U.S. Adolescents

Present address of Dr. G. A. Colditz: Washington University School of Medicine, St. Louis, MO.
https://doi.org/10.1016/j.jadohealth.2007.11.143Get rights and content

Abstract

Purpose

The objectives of this study were to describe longitudinal trends in adolescent physical activity in a sample of U.S. adolescents and to assess the effect of multiple individual, parental, and environmental factors on initial level and rates of change in adolescent physical activity.

Methods

Study subjects were 12,812 boys and girls 10 to 18 years of age who were participating in the Growing Up Today Study and their mothers. We used accelerated longitudinal analysis to describe trajectories of physical activity from 1997–1999, and random effects linear mixed models to determine which factors were independently associated with baseline physical activity and changes in physical activity over time.

Results

Mean hours of physical activity ranged from 7.3–11.6 hours per week in boys and from 8.0–11.2 hours per week in girls. Physical activity was best modeled as a quadratic function of age, increasing until early adolescence and declining after age 13 in boys and girls. Multivariable modeling demonstrated that variables associated with physical activity level at baseline in boys and girls were age, body mass index, psychosocial variables, personal attitudes about body shape, perceived peer attitudes about body shape/fitness, parental attitudes about physical activity, parental physical activity, and environmental barriers to physical activity. Age was the only factor that predicted change in physical activity over time.

Conclusions

Interventions to increase physical activity in adolescents should begin before adolescence. Interventions may be more effective if they are multimodal and focus on modifiable individual, parental, and environmental factors.

Section snippets

Study sample

Study participants were a subset of participants in the Growing Up Today Study (GUTS), a longitudinal study of U.S. adolescents that began in 1996 [11]. The study originally involved adolescents who were offspring of women participating in the Nurses’ Health Study II, a national longitudinal cohort study of >100,000 female nurses. The baseline study was conducted in 1996, and the questionnaire was returned by 9039 girls and 7843 boys. Annual follow-up questionnaires have been returned by 81% to

Results

Hours per week of moderate plus vigorous physical activity in each age cohort by follow-up year are shown in Table 1. Mean hours of physical activity ranged from 7.3 to 11.6 hours per week in boys and from 8.0 to 11.2 hours per week in girls. Using these data, trajectory profiles for moderate plus vigorous physical activity were created for boys and girls (Figure 1, Figure 2). Generally, boys reported higher number of hours of physical activity than girls from approximately age 9 to 12, but

Discussion

In this study, we examined patterns of physical activity over time in a national sample of U.S. adolescents, using recently developed statistical techniques. We also assessed the effect of multiple individual, parental, and environmental factors on initial level and rates of change in adolescent physical activity. In this sample, age was a significant predictor of trends in physical activity over time. Physical activity did not decline in a linear fashion over time with age, but instead

Acknowledgments

This study was funded by the American Cancer Society (RSGPB-04-009-01-CPPB, Dr. Frazier, PI) and the National Institutes of Health (K23 AI50923, Dr. Kahn, PI).

References (39)

  • J.F. Sallis

    Age-related decline in physical activity: a synthesis of human and animal studies

    Med Sci Sports Exerc

    (2000)
  • M. Pratt et al.

    Levels of physical activity and inactivity in children and adults in the United States: current evidence and research issues

    Med Sci Sports Exerc

    (1999)
  • J.F. Sallis et al.

    Correlates of physical activity in a national sample of girls and boys in grades 4 through 12

    Health Psychol

    (1999)
  • P. Gordon-Larsen et al.

    Inequality in the built environment underlies key health disparities in physical activity and obesity

    Pediatrics

    (2006)
  • S.C. Duncan et al.

    A cohort-sequential latent growth model of physical activity from ages 12 to 17 years

    Ann Behav Med

    (2007)
  • C.S. Berkey et al.

    One-year changes in activity and in inactivity among 10- to 15-year-old boys and girls: relationship to change in body mass index

    Pediatrics

    (2003)
  • C.S. Berkey et al.

    Activity, dietary intake, and weight changes in a longitudinal study of preadolescent and adolescent boys and girls

    Pediatrics

    (2000)
  • B.E. Ainsworth et al.

    Compendium of physical activities: classification of energy costs of human physical activities

    Med Sci Sports Exerc

    (1993)
  • K.E. Peterson et al.

    Validation of the Youth Risk Behavioral Surveillance System (YRBSS) Questions on Dietary Behaviors and Physical Activity among Adolescents in Grades 9 through 12

    (1996)

    • Cited by (0)

    View full text
    Copyright © 2008 Society for Adolescent Medicine. Published by Elsevier Inc. All rights reserved.