Obesity is a serious and widespread problem in the United States. Nearly 34% of American adults are obese, and 68% are either obese or overweight (1). In 2007, Louisiana had the third highest rate of obesity in the nation; according to self-reported data, 30.7% of adults were obese (2). Youth and adults in New Orleans are less likely to be physically active than those in the rest of the country (3). Among adults in New Orleans, 38% met the recommended levels of physical activity (PA) compared to 49% nationally. These findings were even more pronounced among low- and moderate-income African Americans (2).

Features of the built environment influence the propensity to be physically active (4-7). PA can be facilitated or constrained by the built environment, although the relationship between individual factors, social factors, and the physical environment is complex and not well understood (8). Making changes to the built environment should be considered as a means of addressing the related problems of obesity and physical inactivity (9). The Institute of Medicine has identified improvements to the built environment that can encourage walking and bicycling, such as a well-connected network of off-street trails and paths and paths connecting destinations for such activity, as a priority (10).

The Prevention Research Center (PRC) at Tulane University works to identify and address physical and social environmental factors that influence the obesity epidemic and has an overall goal of reducing obesity and its associated health problems. In this project, the Partnership for an Active Community Environment (PACE), the PRC worked with neighborhood-based community groups to create improvements to the built environment that would facilitate PA. Taking a community-based participatory research approach (11), we recruited members of local organizations to participate in the project steering committee. The objective of this study was to asses the effect of improvements to the built environment on the PA levels of residents in a low-income, African American community.

We used a serial cross-sectional study design to evaluate the effect of the installation of a path and playground on community-wide PA. We conducted cross-sectional assessments at baseline (fall of 2006) and follow-up (fall of 2008). The changes to the built environment occurred in 2007. The study protocol received approval from the Tulane University institutional review board.

Survey respondents from the 3 neighborhoods were similar demographically at baseline (Table 1). Walking was the most common PA, and participation in any other activity was low (data not shown). Self-reported walking for both transportation and leisure increased from baseline to follow-up for most neighborhoods (Table 2). Because this increase was similar for each neighborhood, the neighborhood-by-time interactions were not significant. Age was neither a confounder nor an effect modifier (data not shown).

People from all neighborhoods reported that they most frequently exercised at sidewalks, mall or stores, and streets (Table 3). No significant neighborhood-by-time interactions were found. Walking trail use increased slightly but nonsignificantly (from 21.9% to 29.6%) in INA.

We found a significant neighborhood-by-time interaction between baseline and follow-up for the proportion of people observed who were active. A significant increase in the proportion of people engaged in moderate and vigorous activity was noted in INA between baseline (36.7%) and follow-up (41.0%) (Pearson χ² test, P < .001) (Figure 2).

We observed a slight, significant increase in vigorous activity from 10.5% to 13.7% in that same area (Pearson χ² test, P < .001) (Figure 3).

We analyzed the combined proportion of moderate and vigorous activity for youth and adults separately and the patterns of moderate and vigorous activity were similar (combined proportions shown) (Figure 2).

The playground was open for 81 weeks, from July 2007 through April 2009. The daily counts of playground users ranged from 1 to 114 (mean daily count, 25 users; data not shown).

We found that after a walking path was installed in a low-income neighborhood, the proportion of people observed who were active in that area increased. Observed activity decreased in the other areas during the same period. Self-reported activity also increased for residents in both intervention areas on streets, for everyone in parks, and for those in INA on a walking trail. However, only the change in park use was significant. The modest increases in observed activity around the path suggest that improvements to the built environment may have had this effect and are encouraging.

It must be noted that the evaluation of the path was not targeted around the path. We hypothesized that environmental changes available to the entire community would lead to increases in PA throughout the neighborhood, as norms for PA changed. However, we could not focus data collection where the built environment was altered because the interventions were decided after baseline data were gathered. Regardless, we were able to show a modest increase in both observed moderate and vigorous activity combined from 36.7% to 41.0% and in observed vigorous activity from 10.5% to 13.7%.

Randomized, controlled trials involving changes to the built environment are difficult to conduct, so most research has been cross-sectional. Our study used cross-sectional assessments before and after the interventions were implemented. In a review article relating features of the built environment to PA in majority African American populations, associations have not been consistent (16). We were unable to find other studies that used objectively measured PA to evaluate interventions to the built environment in primarily African American settings. Objectively measured activity is a better measure of the changes occurring in the neighborhood (17). We also saw some correspondence with the self-reported findings on increase in walking trail use. Our finding is encouraging and confirms cross-sectional studies that find a relationship between features in the built environment and an increase in PA.

Trails and other outdoor recreational spaces in the physical environment promote PA, as evidenced by this study and others (6,18,19). Community-based interventions such as implementing walking paths and trails are a strategy to increase PA levels of residents. A key component to a successful walking path or trail is the ability of residents to have access near their homes and to provide connectivity by linking to destinations (17,20-23). The path in this study was centrally located in the neighborhood and connected a well-used park to a commercial district with markets, shops, and businesses that the neighborhood residents frequent.

Environmental interventions aimed at increasing PA have shown modest results. Fitzhugh et al found an association between objectively measured PA and increased PA after installation of a greenway/trail (24). Their study placed observers in a stationary position in the neighborhood and only captured people being active at the observed location. Our methods allowed us to observe the activity of the entire neighborhood and to count sedentary as well as active people.

The study has several limitations. First, respondents tend to overestimate duration and intensity of PA when the accounts are self-recalled (25). However, systematic observations such as the ones we used are reliable measures of the use of a place or space (26) and may overcome the limitations of self-report (27). Second, when neighborhood is the unit of analysis, randomization is nearly impossible to accomplish, and matching for comparison is even more difficult than matching individuals, making it challenging to control for confounding variables. However, we chose 2 comparable neighborhoods, using census data and the subjective experience and perceptions of steering committee members. The data suggest that these efforts were successful and that communities were well-matched on key variables. Third, the PA observations were limited to streets and yards of houses. Parking lots, areas of commercial lots, and the fenced area of the school yard were not captured in the observations. We were not able to determine whether the users of the school playground were simply displaced from the streets where they may have otherwise played or were new users who were not previously playing outside. Fourth, evaluations of the neighborhoods were broad and encompassed the entire area both in sampling households throughout the neighborhood for the survey and in observing every street in each neighborhood for PA. A more targeted evaluation of the area where the interventions were implemented may have yielded a better measure of effect.

This study has several strengths. The study design included 2 comparison communities, subjective and objective measures of the outcome variables, and 2 waves of data collection. The communities were chosen using objective considerations as well as via the participation of members of the steering committee, who had "insider" perspectives. The interventions were community generated or supported, making them more likely to be accepted and used (11). Contextual variables unique to the time and place (post-Katrina New Orleans) were carefully considered and effectively measured.

Built environment changes, such as easily accessible paths that lead to destinations, can provide more opportunities for PA in primarily African American neighborhoods and others where infrastructure has been allowed to fall into disrepair or was not initially installed. Such increases in opportunity can lead to increases in population-level PA. Environmental interventions can affect many people, over a long period, which programmatic interventions cannot do. Cities and planning commissions should prioritize places for people to be active that are in or near the neighborhoods where people live and consider simple adaptations to existing infrastructure. Resident participation in decision making about the nature and location of environmental changes may be necessary to ensure that changes lead to changes in behavior. As PA levels decrease across the country and in specific communities, creating supportive environments for activity is important. Walking paths or trails may provide a long-term, sustainable, and low-cost strategy to increase the PA of residents in low-income neighborhoods.