School Food and Physical Activity Environment: A Longitudinal Analysis of Four School Districts in New Jersey

Exposures to favorable environments in childhood, including those in schools, are associated with healthy habits among children. In this study, we developed a series of indices aimed at measuring students' exposure to different dimensions of the school food and physical activity (PA) environment. We implemented these indices to investigate how different aspects of the school food and PA environment changed over time and examined their correspondence with known changes in relevant policies and programs.

All public schools (n= 141) in four school districts in New Jersey provided detailed food and PA environment data for each school year from 2010-2011 to 2015-2016. Seven food environment indices, three PA environment indices, and two additional indices that capture health-promoting initiatives at the school level and at the state or federal level were developed.

Although the school PA environment largely remained unchanged, several dimensions of the school food environment changed between 2010-2011 and 2015-2016. Overall, the number of healthy items increased over time in vending machines (p < .001), a la carte (p < .05), or through reimbursable school lunches (p < .001); decreases in number of unhealthy items were only detected in school lunches (p < .05). For most food indices, both the number of items offered and the trend over time varied across school levels.

Schools are a key venue for implementing policy and environment interventions aimed to promote healthy behaviors. Indices developed from easy-to-use survey questions captured multiple dimensions of the school food and PA environments and were sensitive to policy changes over time.