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Open Access Research

Walkability parameters, active transportation and objective physical activity: moderating and mediating effects of motor vehicle ownership in a cross-sectional study

Ulf Eriksson1*, Daniel Arvidsson1, Klaus Gebel345, Henrik Ohlsson1 and Kristina Sundquist12

Author Affiliations

1 Center for Primary Health Care Research, Lund University, Malmö, Sweden

2 Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, California, USA

3 City Futures Research Centre, Faculty of the Built Environment, University of New South Wales, Sydney, Australia

4 School of Education, University of Newcastle, Newcastle, Australia

5 Prevention Research Collaboration, Sydney School of Public Health, University of Sydney, Sydney, Australia

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International Journal of Behavioral Nutrition and Physical Activity 2012, 9:123  doi:10.1186/1479-5868-9-123

Published: 5 October 2012

Abstract

Background

Neighborhood walkability has been associated with physical activity in several studies. However, as environmental correlates of physical activity may be context specific, walkability parameters need to be investigated separately in various countries and contexts. Furthermore, the mechanisms by which walkability affects physical activity have been less investigated. Based on previous research, we hypothesized that vehicle ownership is a potential mediator. We investigated the associations between walkability parameters and physical activity, and the mediating and moderating effects of vehicle ownership on these associations in a large sample of Swedish adults.

Methods

Residential density, street connectivity and land use mix were assessed within polygon-based network buffers (using Geographic Information Systems) for 2,178 men and women. Time spent in moderate to vigorous physical activity was assessed by accelerometers, and walking and cycling for transportation were assessed by the International Physical Activity Questionnaire. Associations were examined by linear regression and adjusted for socio-demographic characteristics. The product of coefficients approach was used to investigate the mediating effect of vehicle ownership.

Results

Residential density and land use mix, but not street connectivity, were significantly associated with time spent in moderate to vigorous physical activity and walking for transportation. Cycling for transportation was not associated with any of the walkability parameters. Vehicle ownership mediated a significant proportion of the association between the walkability parameters and physical activity outcomes. For residential density, vehicle ownership mediated 25% of the association with moderate to vigorous physical activity and 20% of the association with the amount of walking for transportation. For land use mix, the corresponding proportions were 34% and 14%. Vehicle ownership did not moderate any of the associations between the walkability parameters and physical activity outcomes.

Conclusions

Residential density and land use mix were associated with time spent in moderate to vigorous physical activity and walking for transportation. Vehicle ownership was a mediator but not a moderator of these associations. The present findings may be useful for policy makers and city planners when designing neighborhoods that promote physical activity.

Keywords:
Accelerometer; Neighborhood walkability; Geographic information system; Mediator; Moderator