The long-term follow-up and data analysis of two epidemiologic studies, a general population study and a clinical trial provided the basis for the study. The first study assessed the long-term relationship between total physical activity (both during work and leisure time) and mortality in a random sample of 1,656 Black and white men and women residents of the City of Buffalo, New York. The study focused on participants (30+ years of age at baseline) of the Buffalo Health Study, an epidemiological investigation conducted in Buffalo in 1960. As part of the investigation, detailed information was gathered from participants with regard to a number of demographic and socioeconomic characteristics (age, body mass index, education, marital status, etc.) and the participants' usual daily activities (both during a weekday and weekend) at work and outside work. This information was used to compute a total physical activity index. The study related the participants' physical activity characteristics to their all-cause and CHD mortality experience throughout the follow-up period and tested whether or not the relationship between physical activity and mortality was similar across gender and race. The detailed baseline demographic and socioeconomic data allowed analysis of the independence of any observed association between physical activity and mortality.