Association between the physical activity environment in schools and childhood obesity: a view under the light of complex systems

Objective: to analyse the relationship between physical activity (PA) environment at schools and obesity in children, the light of complex systems. Methods: this is a cross sectional study involved 1.200 children (8.1 ± 1.0 years old and 50% boys) from eight public schools from socially vulnerable neighbourhoods of Petrolina, Brazil. Weight and height measurements were assessed to calculate the Body Mass Index (BMI) and classified as normal weight and overweight. To assess the PA environment at the school, a questionnaire about the structural and organizational environment of the school was applied through a face-to-face interview with the school´s manager was conducted. The association between the PA environment at school and obesity was tested using a Machine Learning technique (Network Analysis) performed on the Jasp software. Results: positive associations between BMI and Physical Education classes (0.847), physical education teacher (0.349), break duration (0.564) and indoor sports court (0.662) were observed. Negative associations were seen with sex (-0.212) age (- 0.387), extracurricular PA (-0.492) and playground (-0.557). Additionally, the centrality indicators highlighted extracurricular PA (1.789) as the variables with the highest betweenness values, and BMI with the highest closeness (2.239) and strength (1.230) values. Conclusion: Extracurricular PA and the presence of playgrounds at school´s environment are associated with a healthier weight status low-income children.