A multiple case history and systematic review of adoption, diffusion, implementation and impact of provincial daily physical activity policies in Canadian schools.

Few children meet physical activity (PA) recommendations, and are therefore at increased risk for overweight/obesity and adverse health outcomes. To increase children's opportunities for PA, several Canadian provinces have adopted school-based daily PA (DPA) policies. It is not clear why some jurisdictions have adopted DPA policies, and others have not, nor whether these policies have been implemented and have achieved their intended outcomes. The purpose of this study was to understand the processes underlying adoption and diffusion of Canadian DPA policies, and to review evidence regarding their implementation and impact.