Natural History of Leisure-time Physical Activity and Its Correlates: Associations with Mortality from All Causes and Cardiovascular Disease Over 28 Years

Abstract

The association between leisure-time physical activity and 28-year (1965–1993) nsk of death from all causes and cardiovascular disease was studied in 6,131 adults who participated in the Alameda County Study in Northern California. Because study participants were interviewed on a number of occasions, it was possible to include in the analyses information on changes over time in levels of leisure-time physical activity as well as changes in a wide vanety of other risk factors. There were 47,616 person-years of observation for males (639 deaths from all causes and 321 from cardiovascular disease) and 57,666 person-years of observation for females (587 deaths from all causes and 388 from cardiovascular disease). In analyses in which only the baseline values of all covariates were included, a four-point increase on the leisure-time physical activity scale, the interquartile range, was associated with reduced risk of death from all causes (relative risk (RR) = 0.90, 95% confidence interval (Cl) 0.83–0.99) and cardiovascular disease (RR = 0.85, 95% Cl 0.75–0.97). When time-varying information on leisure-time physical activity and all other covariates was included, there was still a protective effect for all-cause and cardiovascular disease mortality (RR = 0.84, 95% Cl 0.77–0.92 and RR = 0.81, 95% Cl 0.71–0.93, respectively). The association between leisure-time physical activity and risk of death was not altered when information on vanations over time in leisure-time physical activity and many determinants and consequences of physical activity were explicitly included in survival models. Am J Epidemiol 1996; 144:793–7.