There have been few studies examining the possible correlations between PE enrollments and physical activity levels. Using the 1990 YRBSS data, Pate and colleagues (1996) found that 59 percent of high-active students were enrolled in PE as compared to 29 percent of low-active students. As described below, several large-scale school-based intervention studies have demonstrated increases in physical activity in PE classes, but only in isolated smaller scale studies have school interventions increased physical fitness, reduced obesity, or increased physical activity outside of PE classes.
To date, interventions focused on elementary school children have been the most successful at increasing activity levels, with interventions such as Go For Health (Simons-Morton et al., 1997) and SPARK (Sallis et al., 1997) reporting significant increases in the amount of moderate to vigorous physical activity performed during PE classes. In the SPARK intervention, students in the classes taught by physical education specialists spent more time being physically active (40 minutes) than those in the teacher-led classes (33 minutes) or those in control classes (18 minutes) (Sallis et al., 1997).
The largest elementary-school-based intervention to date has been CATCH, a multicenter trial (described above) that tested the effectiveness of a cardiovascular health promotion program in 96 elementary schools. Students in CATCH intervention schools participated in significantly more moderate-to-vigorous physical activity during PE classes than did students in control schools, but significant improvements in physical fitness levels or body weight were not observed (Luepker et al., 1996). An assessment of CATCH 5 years later found that the proportion of PE time spent in moderate to vigorous physical activity had been maintained in intervention schools, but vigorous activity levels declined (McKenzie et al., 2003). School-based programs are less likely to increase physical activity outside of PE classes, although students in the CATCH intervention schools did report participating in more vigorous physical activity during out-of-school hours, an effect that a 3-year follow-up study noted was still being maintained (Nader et al., 1999).
Although some elementary-school-based interventions have shown increased physical activity in PE classes, few have shown significant effects on physiological health risk variables such as body weight or composition. One notable exception was the South Australian Daily Physical Activity Program (Dwyer et al., 1983), which observed the effects of two interventions that markedly increased the exposure of elementary school children to PE. The first intervention emphasized participation in vigorous physical activity through endurance training for 75 minutes every day for 14 weeks, while the second maintained a traditional emphasis on motor-skill instruc-