Impact of Park Size and Access and Neighbourhood Walkability on Physical Activity and Obesity: A Cross-Sectional Analysis

Background: We examined whether higher access to parks and greenspace is independently associated with an increase in physical activity and lower rates of obesity when neighbourhood walkability is accounted for, and to examine whether neighbourhood walkability and park access have synergistic effects on these outcomes. Materials and Methods: We used cross-sectional data from the Canadian Community Health Survey between 2007 and 2014 for adults aged 20 to 74 in Ontario, Canada. Neighbourhood-level access to parks exposures included size of parks and number of parks within 800m of residential areas, and neighbourhood walkability was based on a validated index. The main outcomes were physical activity during leisure time (LPA), both leisure and transportation physical activity (LTPA), and obesity. Descriptive and multivariate logistic regression analyses were conducted, stratified by age groups, accounting for sex, income, ethnicity, and season. Results: Among 41,945 respondents, park access was associated with higher LPA and LTPA, with effects modified by neighbourhood walkability (p< 0.001). Physical activity was highest in neighbourhoods with high walkability and park access and lowest in low walkability areas without parks. In highly walkable neighbourhoods, ≥1 small- or medium-sized park was associated with 29% higher odds of LPA (OR:1.29, 95%CI:1.21–1.37) and 48% higher odds of LTPA (OR:1.48, 95%CI:1.38–1.57) than low walkability/no park access. In contrast, associations were modest in low walkability neighbourhoods (4–7%). High walkability was also associated with lower obesity and marked reductions with very high access to large parks (OR:0.72, 95%CI:0.55–0.94). Findings were consistent across age groups. Conclusion: High neighbourhood walkability was the strongest predictor of physical activity and lower obesity risk, with park access providing additional benefits primarily in already walkable environments. These findings suggest that population health interventions targeting urban design need to consider the combined benefits of neighbourhood walkability and park access on health.