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Exercise Hard, Live Longer

11/25/2004 - Being active and working out doesn’t just make us fit and help us lose weight, it can also add years to our lives. And it’s never too late to start. Even people who are middle aged can expect to live longer, with the risk of death dropping by 23 percent over the next two decades or so after they start exercising.

In fact, when it comes to exercise and longevity, persistence wins out over innate ability. Between a college couch potato who takes up regular exercise in his 40s and the football jock who settle to sedentary life in middle-age, research studies discover that the former will live longer.

In the well-known Harvard Alumni Study, which examined mortality rates over a 22- to 26-year period in more than 17,000 men who had attended Harvard University, life expectancy was about two years longer for those who expended 2,000 calories per week during exercise, compared to individuals who were sedentary. Since 2,000 weekly calories can be consumed during just 15 miles of jogging, it's clear that a fairly modest investment in exercise can bring a large return.

Up to a point, exercise can add years to your life dramatically. From no exercise at all to jogging 10 miles a week improves your chances of living longer significantly. By how much? Ralph Paffenbarger, M.D., one of principal investigators in the Harvard Alumni Study calculated that for each hour that a person exercises, he/she gets roughly two extra hours of life! Paffenbarger's proposition is true only for reasonable amounts of exercise, though (probably for up to 30 weekly miles of running).

How it works

Why does exercise help us live longer? Blood levels of high-density lipoprotein cholesterol (HDL-C) are inversely related to the risk of developing coronary heart disease (the higher the HDL-C, the lower the risk), and exercise raises HDL-C. Running just nine miles per week hikes HDL-C by 8 per cent. Running 17 weekly miles shoots HDL-C up by 12 per cent. Ambling 31 miles per week heightens HDL-C by 19 per cent. Individuals who jog just 11 to 14 miles per week can lower their risk of heart attack by 30 per cent or so.

Exercise also tends to lower blood pressure, decreasing the risk of heart attack and stroke, and trims the chances of becoming obese or developing non-insulin-dependent diabetes mellitus. Regular physical activity has also been linked with lower rates of certain kinds of cancer. In general, exercise extends longevity by diminishing the risk of a variety of different ailments.

Exercise Hard, Live Longer

Science hasn't been exactly clear about the relationship between intensity and longevity, but there is some evidence to support the idea that fairly intense exercise is better than low-intensity stuff. In the Harvard study, for example, expending more than about 400 calories per week in vigorous activity (jogging, fast walking, swimming laps, playing tennis, shovelling snow) was linked with reduced mortality, while spending more than 400 calories per week on non-vigorous efforts (slow walking, moderate yard work, gardening, working on the car, doing light repair around the house, etc.) was not.

Just how intense exercise should be to make a difference? In a separate study which began in England in 1976, the exercise patterns of 9,376 male civil servants, aged 45 to 64, were observed over a nine-year period, during which 474 individuals had a heart attack (272 of which were fatal). The civil servants' exercise was classified as vigorous or non-vigorous, with swimming, jogging, badminton, tennis, football, hockey, hill climbing, and rowing considered vigorous sports, and dancing, golf, and table tennis non-vigorous activities.

In this study, the protective role played by intensity depended on the age of the subjects. Specifically, among those aged 45 to 54, individuals had to engage in intense, vigorous exercise at least twice a week to enjoy a lower risk of heart attack. Infarction rates were reduced by about 67 per cent in these men, compared to individuals who worked out intensely just once a week or not at all. Mortality rates were even lower - down by 80 to 90 per cent for those who worked strenuously at least twice a week, compared to civil servants who trained once a week or less. Working out intensely twice a week seemed to represent a threshold frequency, below which there was no reduction in risk.