Built environment and physical activity: nine-country study of adults with objective measures

Abstract

PURPOSE: The purpose of the present study was to document the strength, shape, and generalizability of associations of built environment variables to total physical activity, using objective measures of independent and dependent variables in an international sample of adults. METHODS: The International Physical activity and Environment Network (IPEN) Adult Study was a coordinated international study, with each country following standard methods as much as possible. The study design was to recruit participants from neighbourhoods selected to be high or low on walkability and high or low on income. Present analyses were done with 6822 adults aged 18-66 years from 14 cities in 9 countries from 5 continents. Seven indicators of walkability, transit access, and park access were assessed in 1-km street network buffers around each participant’s home using Geographic Information Systems (GIS)-based methods. Total minutes of moderate-to-vigorous physical activity (MVPA) were measured by 4+ days of waistworn accelerometer monitoring. Associations of environmental variables with MVPA were estimated using generalized additive mixed models (GAMMs) with Gamma variance and logarithmic link functions, and numerous covariates. RESULTS: Four of 7 individual environmental variables were significantly and linearly related to MVPA: net residential density, intersection density, transit density, and number of parks. Mixed land use variables and distance to nearest transit point were unrelated. The proportional differences in MVPA between residents living in areas with the lowest and highest observed values in individual environmental attributes ranged from ~25% to ~69%. All associations generalized across study sites (i.e., non-significant interactions with site). When adjusting for other environmental variables, only two variables remained significant, with net residential density jointly explaining 10% of between-site and 20% of between-neighbourhood differences in MVPA. CONCLUSION: Using objective data in a study of 14 cities in 9 countries, residential density, intersection density, transit access, and number of parks were positively related to total moderateto-vigorous physical activity, with residential density being the strongest correlate. Generalizability of findings across cities suggests built environment interventions hold promise as a strategy reduce the health burden of the global physical inactivity pandemic.