摘要：Objectives. We conducted a systematic review of the literature examining the relationship between built environments (e.g., parks, trails, sidewalks) and physical activity (PA) or obesity rates. Methods. We performed a 2-step inclusion protocol to identify empirical articles examining any form of built environment and any form of PA (or obesity rate) as the outcome. We extracted data from included abstracts for analysis by using a standard code sheet developed for this study. Results. Of 169 included articles, 89.2% reported beneficial relationships—but virtually all articles utilized simple observational study designs not suited for determining causality. Studies utilizing objective PA measures (e.g., pedometer) were 18% less likely to identify a beneficial relationship. Articles focusing on children in community settings (–14.2%), those examining direct measures of obesity (–6.2%), or those with an academic first author (–3.4%) were less likely to find a beneficial relationship. Conclusions. Policymakers at federal and local levels should encourage more rigorous scientific research to determine whether altered built environments will result in increased PA and decreased obesity rates. Obesity rates have risen dramatically in the United States over the past few decades among both adults 1 and children. 2 Although obesity prevalence has increased in all parts of the country and for all demographic groups, the prevalence of obesity is higher in the US South 3–7 and among African Americans, Hispanics, and the educationally and economically disadvantaged. 2,3,8,9 Obesity and sedentary lifestyles are estimated to result in more than 300 000 premature deaths per year in the United States. 10,11 The obesity epidemic is regarded as one of the leading health problems facing the country and several federal initiatives such as the Centers for Disease Control and Prevention’s “Communities Putting Prevention to Work” or the First Lady’s “Let’s Move” campaign aim to reverse childhood obesity. Ultimately, obesity is a result of imbalance between energy intake and energy expenditure. 12 Physical activity (PA) provides one of the main sources of energy expenditure. 13 In fact, the rising prevalence of obesity in the United States has occurred concurrently with general declines in the rates of PA associated with a decrease in such factors as active transportation (e.g., walking to work or school) and an increase in sedentary leisure-time activities such as television watching 6 and video game playing, 14,15 and a decrease in physical activity in schools. 16 Overall, it is estimated that more than 50% of US adults fail to meet the recommended levels of overall PA, with higher prevalence of inadequate PA in the South. 7 Evidence of inadequacy in PA among children is also well documented. 17–20 It is generally believed that PA is not just a matter of personal choice, but also a function of the built environment 21–23 —which refers broadly to the collective availability of sidewalks, parks, trails, recreational facilities, traffic safety, and other neighborhood characteristics that promote recreational PA as well as active transport to work, school, or errands. 24–29 There is also evidence that low-income neighborhoods and minority communities have less access to recreational facilities 30 and the existing facilities available to them are of a poorer quality. 31 Thus, modifying built environments to make them more PA-friendly is widely advocated as a way to create healthier and less obese communities. 32 Concurrently there has been a growing body of scientific research on how various facets of the built environment are associated with changes in PA or obesity rates. 33–39 However, because of the wide range of scientific journals in which such studies are published, the heterogeneity in types of built environments considered, the different ways in which PA is defined or measured, and the varying study populations examined, it is increasingly difficult for policymakers and other stakeholders to keep abreast of current findings. The purpose of this study was to systematically review the literature examining the relationship between built environments and PA or obesity rates. We were interested in any articles that focused on any aspect of the built environment that also examined any form of PA or direct measures of obesity. Our work supplements previous reviews of the literature that focused narrowly on body weight only, 39 a limited population (e.g., African Americans) 37 or other disadvantaged groups, 38 or literature (e.g., epidemiology only 33 ), and those that were concerned entirely with how to best measure built environments. 35 In addition, previous authors have examined how PA and obesity are related to macro, political, economic, and micro environments 36 or the concept of “smart growth” in the context of urban planning. 34 In our study, we were interested broadly in determining whether built environment characteristics are associated with decreases in obesity or increases in various types of PA. Moreover, we were interested in quantifying the proportion of existing studies that focus on Southern states, on children, or other vulnerable populations, and determining whether such studies differ with respect to identifying a benefit from built environments. Lastly, we were interested in identifying any specific study characteristics that are associated with finding results that show improvements in PA or obesity rates. Overall, our study helps identify gaps in the literature and provides a useful synthesis for policymakers, urban planners, public health professionals, and other stakeholders concerned with maximizing the benefits of built environments for the health of their communities.
