Background
On the eve of the Centennial Olympic Games held in Atlanta, Georgia, the U.S. Surgeon General released a landmark report on physical activity and health.  The Surgeon General reported that 60 percent of American adults are not physically active and 25 percent are completely sedentary.  Recent estimates suggest that sedentary lifestyles are associated with more than 200,000 deaths annually.  Despite the known benefits of regular physical activity, the general trend is toward reduced, rather than increased, physical activity among the U.S. population.

The focus of this study was on the effect of transportation and land use on physical activity levels.  Decentralization of population from central cities and low-density housing patterns, among other factors, have increased reliance on automobile travel over the last several decades.  A fairly extensive body of literature exists on these trends, although debate continues about both the direction and the strength of various causes. 

This study extended this understanding to address the role of transportation and land use on recent increases in sedentary behavior.  It was designed as a framing effort to help sort out the complex factors affecting development and travel; assess the potential for policies that promote more walking, cycling, and transit trips through changes in land use and transport systems; and identify areas for further research.