Objectives: This study examined the association between recreational physical activity and mortality in middle-aged and older women and the possibility that physical activity serves as an important marker of health.
Methods: Analyses were conducted among participants in the Nurses' Health Study. Levels of physical activity were assessed by questionnaire in 1980 and updated every 2 to 4 years.
Results: Levels of physical activity were inversely associated with mortality risk; however, each activity level above the reference level had approximately the same level of risk reduction (20%-30%). The inverse association was stronger for cardiovascular deaths than for cancer deaths and was strongest for respiratory deaths. Women who died of noncardiovascular, noncancer causes were more likely to have reported that poor health limited their physical activity than were women who died of other causes or who remained alive.
Conclusions: Part of the link between physical activity and mortality risk is probably spurious and difficult to remove analytically; however, on the basis of epidemiologic evidence, much of the health benefit of activity is real.