Physical activity as a mediator linking neighborhood environmental supports and obesity in African Americans in the path trial.

ABSTRACT

OBJECTIVE: African Americans have the highest rates of obesity in the United States. Engaging in recommended levels of physical activity (PA) reduces risk for obesity. Social and environmental supports for PA may be important to increase PA. This study hypothesized that PA would mediate the effects of neighborhood and social supports for PA on body mass index (BMI). METHOD: Baseline data were collected from 434 underserved African American adults in the Positive Action for Today's Health (PATH) trial. Features of the neighborhood environment (i.e., infrastructure for walking, access to services, and crime) and peer social support were measured with validated surveys. Moderate-to-vigorous PA (MVPA) was assessed based on 7-day accelerometry estimates (in minutes per day), and self-reported walking and exercise were obtained using the Four-Week Physical Activity History questionnaire. RESULTS: The sample was predominantly female (63%) and obese (MBMI = 30.88 kg/m², SD = 8.43). Neither crime nor social support was significantly associated with either PA or BMI; thus, they were excluded from the final models. Infrastructure for walking predicted MVPA (B = 4.06, p = .01) and self-reported walking (B = 7.39, p = .03). A positive association between access to services and MVPA approached significance (B = 2.27, p = .06). MVPA (B = -0.07, p < .001) and self-reported walking (B = -0.02, p = .01) predicted BMI, but only MVPA mediated the effect of infrastructure for walking on BMI (B = -0.03, p = .04). No significant direct or indirect effects of predictors were found for self-reported exercise. CONCLUSION: Findings suggest that MVPA is a mediator linking infrastructure for walking and BMI in underserved communities.