Impact of a school-level intervention on leisure-time physical activity levels on school grounds in under-resourced school districts.

Even the best school physical education programs fall short of providing enough physical activity (PA) to meet students' PA guidelines thus increasing PA at other times throughout the school day could help students meet recommended PA levels. Unstructured leisure-time periods during the school day represent an opportunity to promote PA, particularly among students in underserved school districts. Between 2014 and 2018, we partnered with 14 elementary and 5 secondary schools in low-income Latino communities to increase students' leisure time moderate to vigorous physical activity (MVPA). Schools received consultation and technical assistance on their wellness policy, and some created wellness committees. Schools selected 1-2 PA/nutrition promotion activities for the academic year. Following the System for Observing Play and Leisure Activity in Youth protocol, we conducted a pre- vs. post- analysis of observations of school time student PA (levels of MVPA, energy expenditure, proportion of areas in which games and sports were prominent) in 4936 pre-intervention play areas and 4404 post-intervention areas before school, during lunch recess, and after school. We utilized linear and logistic regression analyses to test pre/post changes in these dependent variables using school area characteristics, period of observation, and temperature as covariates. Following our intervention, MVPA levels before school, during lunch recess, and after school increased significantly from 19.8% at baseline to 25.6% among elementary girls and from 25.4% to 33.2% among elementary boys. Decomposition of these effects suggested that the benefits were partially mediated by increased adult playground supervision. We did not observe any significant changes in PA levels among secondary school girls or boys. Our school-level intervention aimed at promoting PA was associated with modest but meaningful increases in leisure-time PA among elementary, but not secondary, school students. The effects were attributable in part to increased adult supervision on the playground.