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Phys Ed Gretchen Reynolds on the science of fitness.

Running for as little as five minutes a day could significantly lower a person’s risk of dying prematurely, according to a large-scale new study of exercise and mortality. The findings suggest that the benefits of even small amounts of vigorous exercise may be much greater than experts had assumed.

In recent years, moderate exercise, such as brisk walking, has been the focus of a great deal of exercise science and most exercise recommendations. The government’s formal 2008 exercise guidelines, for instance, suggest that people should engage in about 30 minutes of moderate exercise on most days of the week. Almost as an afterthought, the recommendations point out that half as much, or about 15 minutes a day of vigorous exercise, should be equally beneficial.

But the science to support that number had been relatively paltry, with few substantial studies having carefully tracked how much vigorous exercise is needed to reduce disease risk and increase lifespan. Even fewer studies had looked at how small an amount of vigorous exercise might achieve that same result.

So for the new study, published Monday in The Journal of the American College of Cardiology, researchers from Iowa State University, the University of South Carolina, the Pennington Biomedical Research Center in Baton Rouge, La., and other institutions turned to a huge database maintained at the Cooper Clinic and Cooper Institute in Dallas.

For decades, researchers there have been collecting information about the health of tens of thousands of men and women visiting the clinic for a check-up. These adults, after completing extensive medical and fitness examinations, have filled out questionnaires about their exercise habits, including whether, how often and how speedily they ran.

From this database, the researchers chose the records of 55,137 healthy men and women ages 18 to 100 who had visited the clinic at least 15 years before the start of the study. Of this group, 24 percent identified themselves as runners, although their typical mileage and pace varied widely.

The researchers then checked death records for these adults. In the intervening 15 or so years, almost 3,500 had died, many from heart disease.

But the runners were much less susceptible than the nonrunners. The runners’ risk of dying from any cause was 30 percent lower than that for the nonrunners, and their risk of dying from heart disease was 45 percent lower than for nonrunners, even when the researchers adjusted for being overweight or for smoking (although not many of the runners smoked). And even overweight smokers who ran were less likely to die prematurely than people who did not run, whatever their weight or smoking habits.

As a group, runners gained about three extra years of life compared with those adults who never ran.

Remarkably, these benefits were about the same no matter how much or little people ran. Those who hit the paths for 150 minutes or more a week, or who were particularly speedy, clipping off six-minute miles or better, lived longer than those who didn’t run. But they didn’t live significantly longer those who ran the least, including people running as little as five or 10 minutes a day at a leisurely pace of 10 minutes a mile or slower.

“We think this is really encouraging news,” said Timothy Church, a professor at the Pennington Institute who holds the John S. McIlHenny Endowed Chair in Health Wisdom and co-authored the study. “We’re not talking about training for a marathon,” he said, or even for a 5-kilometer (3.1-mile) race. “Most people can fit in five minutes a day of running,” he said, “no matter how busy they are, and the benefits in terms of mortality are remarkable.”

The study did not directly examine how and why running affected the risk of premature death, he said, or whether running was the only exercise that provided such benefits. The researchers did find that in general, runners had less risk of dying than people who engaged in more moderate activities such as walking.

But “there’s not necessarily something magical about running, per se,” Dr. Church said. Instead, it’s likely that exercise intensity is the key to improving longevity, he said, adding, “Running just happens to be the most convenient way for most people to exercise intensely.”

Anyone who has never run in the past or has health issues should, of course, consult a doctor before starting a running program, Dr. Church said. And if, after trying for a solid five minutes, you’re just not enjoying running, switch activities, he added. Jump rope. Vigorously pedal a stationary bike. Or choose any other strenuous activity. Five minutes of taxing effort might add years to your life.