Examining the state, quality and strength of the evidence in the research on built environments and physical activity among adults: An overview of reviews from high income countries.

Background: Built environments have been implicated in the development of chronic disease, with physical activity (PA) considered one of the critical mechanisms for this relationship. Substantial growth in research on built environments and PA makes navigating the available evidence challenging.

Objective: To examine and describe the current state, strength and quality of research investigating the associations between built environments and PA domains of active living (i.e., leisure, transportation, occupational) and total PA among adults (≥18 years) from high-income OECD countries.

Methods: We conducted an overview of systematic reviews. A systematic search of six bibliographic databases and grey literature from January 2000 to May 2020. Review quality was assessed with the AMSTAR2. Results by age group were synthesized narratively and direction of association displayed using harvest plots. Certainty of the evidence was assessed using a modified GRADE approach.

Results: The overview included 116 systematic reviews. Most evidence was cross-sectional and of low-to-very low quality. Moderate-to-high certainty of evidence supported positive associations between environments that support active transportation (e.g., walkability, walking infrastructure, street connectivity, land-use mix) and transportation PA among adults/working-aged adults. Across all age groups, there was very low-to-moderate certainty for consistent positive associations between point of decision prompts (e.g., signs in stairwells and along paths) and all PA. Evidence from older adults was of very low certainty and largely equivocal. There was little-to-no evidence for young and middle-aged adults and occupational PA.

Discussion: While there has been an increase in evidence from observational and natural experiment studies, most has been related to active transportation infrastructure and point of decision prompts. There remains a need for these studies to evaluate built environments for leisure and occupational PA and among younger and older adults, and for high quality reviews to summarize this evidence. Interventions that target changes to the built environment show promise for promoting PA among adults, providing an important means to combat the global physical inactivity crisis.