If you increase your heart rate, will your life span follow?
That possibility is at the heart of an ambitious new study of exercise and mortality. The study, one of the largest and longest-term experimental examinations to date of exercise and mortality, shows that older men and women who exercise in almost any fashion are relatively unlikely to die prematurely. But if some of that exercise is intense, the study also finds, the risk of early mortality declines even more, and the quality of people’s lives climbs.
Scientists have known for some time, of course, that active people tend also to be long-lived people. According to multiple past studies, regular exercise is strongly associated with greater longevity, even if the exercise amounts to only a few minutes a week.
But almost all of these studies have been observational, meaning they looked at people’s lives at a moment in time, determined how much they moved at that point, and later checked to see whether and when they passed away. Such studies can pinpoint associations between exercise and life spans, but they cannot prove that moving actually causes people to live longer, only that activity and longevity are linked.
To find out if exercise directly affects life spans, researchers would have to enroll volunteers in long-term, randomized controlled trials, with some people exercising, while others work out differently or not at all. The researchers then would have to follow all of these people for years, until a sufficiently large number died to allow for statistical comparisons of the groups.
Such studies, however, are dauntingly complicated and expensive, one reason they are rarely done. They may also be limited, since, over the course of a typical experiment, few adults may die. This is providential for those who enroll in the study but problematic for the scientists hoping to study mortality; with scant deaths, they cannot tell if exercise is having a meaningful impact on life spans.
