When worlds collide: observations on the integration of epidemiology and transportation behavioral analysis in the study of walking.

Since obesity has emerged as a public health crisis in the United States, the factors that influence physical activity are of interest to both epidemiologists and transportation researchers. This article describes different approaches taken by the two disciplines to this issue. "Utilitarian" walking to accomplish a task, as opposed to structured exercise, could be a highly sustainable way for people to achieve recommended levels of physical activity. Transportation planners have begun to investigate factors of urban form and transportation services that influence the choice to walk. Epidemiologists have become more aware of the importance of factors in the built and social environment that could influence health behaviors like walking. Few transportation studies focus on the generation of the utilitarian walk trip as the key variable; rather, they include it in more general discussions of urban form. Likewise, most epidemiologic studies have not focused on utilitarian walking, but have folded it into an overall measure of physical activity that emphasizes structured exercise. Further transportation research should examine the effects of improved mobility services in addition to alterations of the built environment. Integration of epidemiologic and transportation behavioral research could enhance our understanding of the role of urban and transportation factors on physical activity.