BACKGROUND:
The Report of the Surgeon General on Physical Activity and Health (USDHHS, 1996) emphasized that regular physical activity has important health benefits including reducing the risk of heart disease, and helping to treat and prevent high blood pressure, high cholesterol, and diabetes, and to prevent osteoporosis and colon cancer. In addition, physical activity helps control weight, reduces feelings of depression and anxiety, and promotes psychological well being. Inactivity increases with age and is more common among women than men and among those with lower income, less education, and in minorities (USDHHS, 1996). Even though adolescents are more active than adults, many do not engage in recommended levels of physical activity, and participation declines with age throughout adolescence, especially in girls (USDHHS, 1996; CDC, 1997). Fourteen percent of teenage girls get no regular exercise, twice the percentage as for boys. The proportion of adolescent girls who participate in regular vigorous physical activity declines dramatically each year they are in high school, from 61 percent among 9th graders to 41percent among 12th grade girls. In high school, enrollment for girls in daily physical education classes dropped from 41 percent in 1991 to 25 percent in 1995. Both the CDC report (1997) and the Surgeon General's Report (USDHHS, 1996) recommended the need for research testing the effectiveness of a coordinated school-based physical activity intervention linked to community agency programs to increase physical activity by adolescent girls.
The study is the result of a Request for Applications released in January, 2000. Awards were made in September 2000.
DESIGN NARRATIVE:
The purpose of the multicenter randomized trial is to test the effectiveness of a multicomponent school-based and community-linked intervention in preventing the decline in physical activity levels and cardiovascular fitness in middle school girls (i.e., in grades 6-8). The interventions will provide skills-building, supportive environments, and opportunities for participation in physical activity during and outside of the school day. Phase 1 will be 24 months for protocol development and pilot work, Phase II is 44 months for two years of intervention and one year of follow-up, and Phase III is 4 months for close out of the Study Centers, and 16 months for the Coordinating Center to collaboratively analyze and report the results.
The randomized trial of 36 middle schools (6 per field site) will collect data by two-cross sectional samples, one taken at the sixth grade (at least 1,728 girls) in the Spring of 2003 and the other taken at the eighth grade (at least 3,456 girls) in the Spring of 2005. Follow-up data collection will also occur at the eighth grade in the Spring of 2006.
