Background
Many states have passed legislation to mandate a minimum amount of physical education (PE) per week for students. Though there is evidence that such policies increase PE attendance, time requirement policies may not reduce socioeconomic disparities in physical activity for multiple reasons. First, PE attendance is not where socioeconomic disparities lie; adolescents of low socioeconomic status (SES) generally have lower activity levels despite having similar rates of PE. Second, many students are not physically active during PE. A small number of states have supplemented PE time requirements with policies to require a minimum amount of moderate-to-vigorous physical activity (MVPA) during PE class. Such policies may be more effective at reducing socioeconomic disparities in activity.

Objectives
To determine if socioeconomic disparities in physical activity are smaller in states with PE time requirement policies or states with both PE time requirement policies and policies regarding a minimum amount of MVPA during PE class, relative to states with neither policy.

Methods
Data on student physical activity, PE attendance, and household SES were obtained for 6,300 eighth-grade public school students in 40 states in Spring 2007 as part of the Early Childhood Longitudinal Study - Kindergarten Class. Students were asked to report the number of days on which they “exercised or participated in physical activity that made them sweat and breathe hard for at least 20 minutes,” within the past seven days, and the number of days they attend PE in an average week. Student SES was measured using an index that combined data on household income, parental education, and parental occupation, as reported in an interview with parents. State policies regarding PE time requirements and MVPA during PE were compiled by the Bridging the Gap Program through primary legal research methods, and verified against secondary sources. Analyses are based on middle school policies in the 2006-07 school year.  States were categorized based on whether they had a policy requiring a minimum amount of PE per week, but no policy regarding MVPA during PE (n=9); required both a minimum amount of PE per week and a minimum amount of MVPA during PE (n=5); or had neither policy (n=26). General linear models, with an identity link, were used to estimate the differences between categories in average days of PE and average days of activity per week among 8th grade students. After estimating overall differences, interaction terms between policy category and SES quintile were used to estimate the difference between categories in SES disparities of PE and physical activity. Models were stratified by gender and adjusted for age, race/ethnicity, Census region, and locale. A robust standard error was used to account for state clustering.

Results
Girls and boys in the lowest SES quintile reported an average of 3.81 and 4.50 days of activity, respectively, while those in the highest SES quintile reported an average of 4.69 and 5.00 days of activity, respectively. Days of PE were similar across all SES quintiles in both gender groups (mean=3.07). In states that had PE time requirement policies but no policy regarding MVPA during PE, girls’ mean PE attendance was 0.99 days/week higher (95% confidence interval (CI): 0.18, 1.80), relative to states with neither policy, but their mean days of activity was similar (β=0.08, 95% CI: -0.12, 0.29). Girls in states with both PE time requirement policies and policies regarding MVPA during PE also had the same mean days of activity (β=0.07, 95% CI: -0.25, 0.40). None of the associations between state policy and PE or physical activity varied by SES quintile among girls. Boys, in contrast, reported more days of activity if they resided in states with PE time requirement policies (β=0.34, 95% CI: 0.16, 0.51) or policies regarding MVPA during PE (β=0.32, 95% CI: -0.01, 0.51). The association between PE time requirement policies and days of activity was similar across SES quintiles; even in states with PE time requirements, boys in the highest SES quintile reported an average of 0.54 more days of activity than boys in the lowest SES quintile. The disparity in activity was significantly smaller in states that required a minimum amount of MVPA during PE, however (β=-0.64, 95% CI: -1.23, -0.06), such that boys at opposite ends of the SES distribution had nearly identical levels of activity. Boys in the lowest SES quintile in those states reported an adjusted mean of 4.90 days of activity (95% CI: 4.55, 5.24).

Conclusions
State policies that require students to participate in PE may be effective at increasing PE attendance for the overall student population, particularly among girls, but they are ineffective at reducing socioeconomic disparities in physical activity. Policies that require a minimum level of MVPA during PE may be a more promising method of reducing socioeconomic disparities in activity among boys.

Support/Funding
The Robert Wood Johnson Foundation and the National Heart, Lung, and Blood Institute.