摘要：Objectives. Using data from a large cohort of adults aged 45 to 84 years-old, we investigated whether availability of recreational resources is related to physical activity levels. Methods. Data from a multiethnic sample of 2723 adult residents of New York City, NY; Baltimore, Md; and Forsyth County, NC, were linked to data on locations of recreational resources. We measured the availability (density) of resources within 0.5 (0.8 km), 1, 2, and 5 miles of each participant’s residence and used binomial regression to investigate associations of density with physical activity. Results. After adjustment for potential confounders, individuals in the tertile of participants residing in areas with the highest density of resources were more likely to report physical activity during a typical week than were individuals in the lowest tertile. Associations between availability of recreational resources and physical activity levels were not present for the smallest area assessed (0.5 miles) but were present for areas ranging from 1 to 5 miles. These associations were slightly stronger among minority and low-income residents. Conclusions. Availability of resources may be 1 of several environmental factors that influence individuals’ physical activity behaviors. The growing attention to obesity as a public health problem has generated interest in how features of residential environments, including the built environment, influence physical activity. 1 – 3 A parallel body of work has shown that neighborhood socioeconomic characteristics are related to cardiovascular risk, even after control for individual socioeconomic indicators. 4 , 5 The extent to which these associations are causal and the processes through which neighborhood effects might be mediated remain subjects for research. Availability of physical activity resources is 1 mechanism postulated to explain neighborhood differences in cardiovascular risk. Past work on residential environments and physical activity has been hampered by limited data on the specific features of residential environments that may be relevant. 6 A growing body of recent work has begun to measure features of the physical environment using survey data as well as objective measures of the location of recreational facilities. 7 The presence of a positive association between objective availability of resources and physical activity would suggest that improving spatial access to resources is an appropriate strategy to increase population levels of activity. Evidence on whether availability of physical activity resources is an important predictor of physical activity behavior is mixed. 8 – 22 Although important, existing research has focused largely on simple measures, such as distance to selected facilities or number of facilities within a given area, 8 – 10 , 13 – 19 , 22 that do not account for the resources offered at a particular location. In addition, these studies have viewed space as discrete areas rather than a continuous field. Questions remain regarding the relevant spatial scale and sensitivity of empirical results to different spatial scales. Using data from a large, multiethnic cohort of adults aged 45 to 84 years-old, we investigated associations between objective measures of the availability of recreational resources and physical activity. We used geographic information system methods to quantify the density (per area and per population) of physical activity resources weighted by the number and types of activities available at each location. We hypothesized that greater availability of recreational resources would be associated with a greater probability of residents being physically active. Because individual characteristics may result in individuals being more or less dependent on local resources, we also investigated whether any associations observed differed according to individual-level income or race/ethnicity. In the absence of an a priori theory on how the distance one must travel to access recreational resources affects one’s use of those resources, we explored areas (“windows”) of different sizes (0.5 miles [0.8 km], 1 mile, 2 miles, and 5 miles) around each person’s home. Our a priori assumption was that, within a window of a given size, resources closer to one’s residence would have more effect on physical activity than those further from one’s residence. Therefore, kernel densities (which assign more weight to resources closer to one’s residence than those closer to the boundary of the window) were our primary measure of resource availability. However, in addition, we examined whether results differed when simple densities (which assume equal effects of all resources located within the window) were used. Although the presence of a resource may affect physical activity regardless of the number of people who reside in the area, the presence of a larger population also implies more competition for the resources available. We therefore examined whether our results differed when density of resources was calculated in terms of population or simply in terms of area.
