Research article
Built Environment, Adiposity, and Physical Activity in Adults Aged 50–75

https://doi.org/10.1016/j.amepre.2008.03.021Get rights and content

Background

Few studies have investigated the built environment and its association with health—especially excess adiposity—and physical activity in the immediate pre-Baby Boom/early-Baby Boom generations, soon to be the dominant demographic in the U.S. The purpose of this study was to examine this relationship.

Methods

This study used a cross-sectional, multilevel design with neighborhoods as the primary sampling unit (PSU). Residents (N=1221; aged 50–75) were recruited from 120 neighborhoods in Portland OR. The independent variables at the PSU level involved GIS-derived measures of land-use mix, distribution of fast-food outlets, street connectivity, access to public transportation, and green and open spaces. Dependent variables included resident-level measures of excess adiposity (BMI ≥25), three walking activities, and physical activity. Data were collected in 2006–2007 and analyzed in 2007.

Results

Each unit (i.e., 10%) increase in land-use mix was associated with a 25% reduction in the prevalence of overweight/obesity. However, a 1-SD increase in the density of fast-food outlets was associated with a 7% increase in overweight/obesity. Higher mixed-use land was positively associated with all three types of walking activities and the meeting of physical activity recommendations. Neighborhoods with high street connectivity, high density of public transit stations, and green and open spaces were related in varying degrees to walking and the meeting of physical activity recommendations. The analyses adjusted for neighborhood- and resident-level sociodemographic characteristics.

Conclusions

Findings suggest the need for public health and city planning officials to address modifiable neighborhood-level, built-environment characteristics to create more livable residential communities aimed at both addressing factors that may influence unhealthy eating and promoting active, healthy lifestyles in this rapidly growing population.

Introduction

The incidence and prevalence of overweight and obesity have reached epidemic proportions in the U.S.,1, 2 and they pose a serious threat to public health.3 Although physical activity is known to be important in preventing or decreasing weight gain, research indicates that the majority of U.S. adults are either insufficiently active or sedentary.4, 5, 6, 7, 8 It is well documented that obesity, physical inactivity, or the combination is associated with an increased risk of common chronic diseases, including coronary heart disease, stroke, some cancers, and type 2 diabetes.9 While obesity and physical inactivity result from the interaction of genetic, behavioral, and environmental factors, there is growing research interest in how these problems are associated with the built environment.10, 11, 12, 13, 14, 15, 16, 17, 18 In this respect, accumulating evidence—primarily from cross-sectional studies—has shown how social, physical, and built-environment conditions may adversely affect health by facilitating unhealthy eating and compromising physical activity.19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30

Despite the increase in research on obesity and physical inactivity, there is a paucity of information on built-environment factors and their associations with health and physical activity in a population inclusive of the immediate pre-Baby Boom/early-Baby Boom generations, which will become the major demographic related to healthcare utilization in the next 20 years. According to the U.S. Census Bureau,31 by 2030 people aged ≥50 will constitute 36% of the total U.S. population (compared to 24.9% currently), and the numbers of those aged ≥60 will more than double from current levels (ranging from an 82% increase in people aged 60–64 to a 126% increase in those aged ≥85). The continuing increase in the number of older adults who are overweight or obese32 or who do not regularly engage in physical activity4 makes critical an understanding of how neighborhood built-environments may affect health and physical activity in this population.

This study examined, via a cross-sectional design, the associations among built-environment factors (representing dimensions of urban form), the prevalence of overweight/obesity, and various forms of physical activity among middle-aged and older adults. It was postulated that the neighborhood built-environment factors specified in this study would independently account for neighborhood-level variation in residents' levels of being overweight/obese and physically active. On the basis of prior research,19, 20, 22, 25, 26, 27, 29, 33 the specific hypotheses were that neighborhoods with lower mixed-land use and higher densities of fast-food outlets would be associated with more residents being overweight/obese, and that residents living in neighborhoods with higher mixed-land use, high street connectivity, better access to public transportation, and more green and open spaces for recreation would be more likely to engage in neighborhood and utilitarian-related walking, as well as to meet the recommended guidelines for physical activity.

Section snippets

The Study's Geographic Area

The study's geographic area covered the Portland OR metropolitan region's urban growth boundary (UGB). The UGB, created as part of the statewide land-use planning program, is a legal boundary to protect farms and forests from urban sprawl and to promote the efficient use of land, public facilities, and services inside the boundary. The 2005 UGB contained 798 census block groups (a subdivision of U.S. census tracts), encompassing approximately 400 square miles (about 256,345 acres) across the

Dependent Measures

Objective anthropometric measures of body weight (in pounds) and height (in inches) were obtained from the study participants. BMI was calculated as weight/height2 (kg/m2) and assigned to two categories: 1=overweight or obese (BMI ≥25); 0=otherwise (BMI <25). Physical activity measures were: (1) neighborhood walking; (2) walking for transportation (e.g., to catch a bus, light rail, or train); (3) walking for household errands (e.g., shopping or banking); and (4) measures of physical activity

Sample Characteristics

Valid responses were obtained from 1221 respondents (a 48% response rate from all selected participants initially contacted). All participants' addresses were successfully geo-matched for an accuracy level of 100%. The map showing the geocoded home locations of participants across the 120 study neighborhoods is displayed in Figure 1.

Table 1 shows the descriptive statistics for the study sample and by gender. Respondents were aged 50–75 (mean age=62 years, SD=6.89 years). The majority of

Discussion

The results from this study showed significant associations among built-environment factors and the prevalence of overweight/obesity and various forms of physical activity in middle-aged and older adults. Controlling for neighborhood- and resident-level sociodemographic characteristics, neighborhoods with lower mixed-land use and higher densities of fast-food outlets were more likely to have residents who were overweight/obese. In contrast, residents living in neighborhoods with higher

Conclusion

The current study contributes to the environment and health literature by documenting associations among built-environment factors, particularly those related to urban form, and overweight/obesity and physical activity in a sample of middle-aged and older adults. On the basis of the cross-sectional analysis results, findings indicate that lower mixed-land use and higher densities of fast-food outlets in a neighborhood are associated with a higher prevalence of overweight/obesity in local

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