tion but increased the duration and frequency to 75 minutes every day. Both of these interventions were compared to traditional PE classes for 30 minutes three days per week. Only the intervention that emphasized vigorous physical activity produced a significant reduction in skinfold thickness and an increase in objectively measured physical fitness, while traditional PE, even at increased frequency and duration, did not. The findings of this study suggest that physical education has the potential to improve body composition in children, but only if activity is at high intensity, with increases in frequency and duration. Physical education classes of 75 or more minutes are not feasible within most current school days; however, the impact of this intervention on students’ BMI encourages the development of approaches for increasing physical activity that can realistically be implemented.

The other PE intervention that has demonstrated significant effects on body weight was the Stanford Dance for Health intervention, which substituted popular and aerobic dance classes (40 to 50 minutes, three times per week, over 12 weeks) for the standard physical activity class (Flores, 1995). In a randomized controlled trial among mostly low-income African-American and Latino middle-school students, girls who were randomized to the dance intervention significantly improved their physical fitness and reduced their BMI gain compared to girls in the standard class. There were no significant differences among boys. As in the South Australian study, changes in fitness and body weight/fatness were seen when the content of PE was made more vigorous.

A small number of school-based studies have focused on increasing physical activity in older students. The Lifestyle Education for Activity Program was a group randomized trial that examined the effects of a comprehensive school-based intervention on high school girls’ physical activity levels. Girls in the intervention schools were significantly more likely to participate in vigorous physical activity, both in PE classes and in other settings, than girls in the control schools (Dishman et al., 2004). The Middle-School Physical Activity and Nutrition study tested the effects of an environmental and policy intervention on physical activity and fat intake in 24 middle schools. Boys in the intervention schools participated in significantly more physical activity than boys in the control schools, both in and out of PE classes. The same across-the-board effect was not observed for girls, although girls in the intervention schools did participate in more physical activity during PE classes (Sallis et al., 2003). The study found significant reductions in the BMIs of boys in the intervention schools as compared to boys in the control schools, based on self-reports of height and weight; however, similar results were not seen for girls. Issues regarding gender differences had been considered (e.g., the outside-of-PE component of the intervention was staffed primarily by female volunteers and the study

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