Background: There is little national research on longitudinal patterns of physical activity and sedentary behavior in ethnically diverse teens as they transition to adulthood.

Methods: Longitudinal questionnaire data from U.S. adolescents enrolled in Wave I (1994-1995) and Wave III (2001) of the National Longitudinal Study of Adolescent Health (n =13,030) were analyzed in January 2004. Incidence, reversal, and maintenance of achieving five or more weekly bouts of moderate to vigorous physical activity (MVPA) and < or =14 hours of weekly TV and video viewing, computer/video game use (screen time) were assessed. Multinomial logistic regression models examined the likelihood of achieving five or more weekly sessions of MVPA week and < or =14 hours screen time per week as an adolescent and/or young adult, controlling for household income, parental education, age of adolescent, and seasonality.

Results: Of those achieving five or more weekly sessions of MVPA and < or =14 hours of weekly screen time as adolescents, few continued to achieve these favorable amounts of activity (4.4%) and screen time (37.0%) as adults. More failed to maintain these favorable amounts of activity (31.1%) and screen time (17.3%) into adulthood. Black versus white females were more likely to maintain less [corrected] favorable amounts of activity from adolescence to adulthood (odds ratio [OR]=3.09; 95% confidence interval [CI]=1.49-6.42), while black males (OR=1.50; CI=1.05-2.14) and females (OR=2.00; CI=1.40-2.87) were more likely than whites to maintain less (versus more) favorable screen time hours.

Conclusions: The vast majority of adolescents do not achieve five or more bouts of moderate physical activity per week, and continue to fail to achieve this amount of activity into adulthood.