Objective: To examine changes in physical activity during a 19-year period between 2 representative cohorts of adolescents from New South Wales, Australia.
Design: Repeat cross-sectional study.
Setting: Randomly selected secondary schools fromNew South Wales, the most populous state in Australia.
Participants: One thousand fifty-five adolescents surveyed in May through October 1985 (with the Australian Health and Fitness Survey) and 1226 adolescents surveyed in March through April 2004 (with the New South Wales Schools Physical Activity and Nutrition Survey). Participants were aged 12 to 15 years.
Main Outcome Measures: The proportion meeting current guidelines for physical activity (60 min/d of moderate to vigorous physical activity) and time spent in moderate to vigorous physical activity assessed by selfreported participation in physical activity using the same questionnaire at both time points.
Results: All of the age and sex groups reported increases in both the prevalence of physical activity (mean increase range, 11.7%-20.0%) and in the minutes per week spent in moderate to vigorous physical activity (median increase range, 135-175 minutes). These findings remained the same after additional adjustment for age, socioeconomic status, and cultural background.
Conclusions: Physical activity participation has considerably increased during the past 19 years among adolescents in the state of New South Wales, Australia. These findings provide important information about trends in compliance with physical activity recommendations and in time spent in physical activity. They could help to explain what aspects may need to be promoted to maximize the role of physical activity in reducing the high and increasing rates of child and adolescent obesity.