Sex differences and the built environment: possible solution for the increasing levels of sedentary behaviour

Abstract

OBJECTIVE: Prolonged sitting has become a pervasive component of adults’ lives. New evidence indicates that prolonged periods of inactivity, induced through sitting, have detrimental health effects. While recent cross-sectional evidence suggests a link between physical activity and built environment in adults, there is little research exploring the relationship between sedentary behavior and the built environment. We estimated the strength and shape of associations of GIS-determined walkability components of individual residential buffer zones with accelerometer-assessed sedentary time. We also explored whether these associations varied by gender, study site and type of day (weekday versus weekend). METHODS: The Understanding of the Relationship between the Built environment And Neighborhood (URBAN) study was conducted in forty-eight neighborhoods across four cities (Waitakere, North Shore, Christchurch, Wellington) in New Zealand between August 2008 and October 2010. Neighborhoods were stratified on GIS-based walkability measures. The outcome measure was average daily minutes of sedentary time estimated from the hourly accelerometer data from 1762 participants (aged 41.4 ± 12.1; 58% female). Participants wore an accelerometer for seven days. Sedentary time was operationalized as <100 accelerometer counts per minute. The exposure measures were GIS-based walkability components (dwelling density, street connectivity, land use mix and net retail floor area ratio) for residential buffers of 500 m and 1000 m radii. Data were analyzed using Generalized Additive Mixed Models in R. RESULTS: No significant main effects of GIS-based walkability were found on sedentary time. However, significant net retail floor area ratio by gender and street connectivity by study site interaction effects were observed. Retail floor area ratio was negatively associated with sedentary time in women. This effect was stronger and significant only for 500 m residential buffers. Among participants from Christchurch only, an increase of 1 decile in street connectivity was associated with a decrease of over 5 minutes of sedentary time per day. This effect was observed for both residential buffer sizes. CONCLUSIONS: Neighborhoods with retail within close distance are associated with less sedentary time in female residents. The effects of street connectivity were location specific as a significant association was found for one city only.