It's well known by now that active people typically live longer than those who are sedentary. But precisely what types or amounts of exercise most affect life span has not been clear. Several new studies, though, are beginning to provide some clarity, suggesting that certain activities may be better than others in terms of affecting mortality risk.
Perhaps the most memorable of the new studies was conducted by researchers in Europe who turned to a large database of health informationabout middle-aged British civil servants. The workers, ages 35 to 55 at the start, were followed for a decade or so, during which time they filled out repeated health questionnaires.
The topics included each man or woman's physical activity during the previous month. Specifically, the questionnaires asked about the number of hours that the volunteers had spent walking, gardening, performing housework, playing sports (swimming, cycling, golf or soccer) and puttering around the house completing yardwork and do-it-yourself repair projects.
Each activity was designated as "mild," like washing the dishes and cooking; "moderate," encompassing weeding and brisk walking; or "vigorous," which here included swimming and mowing the yard. (Riding mowers apparently didn't factor in.)
The researchers also checked death records for the civil servants.
They found that in general, physical activity of any kind was associated with longer life. But the association was much stronger among those people whose activities were relatively intense. Those who regularly painted and repaired their houses or walked briskly enjoyed more protection against premature death than those who washed dishes, even if people spent more overall hours engaged in "mild" activities.
That finding agrees with those of a study published this year in The European Journal of Preventive Cardiology, in which scientists in Copenhagen followed 5,106 adult recreational cyclists for about 18 years, asking their volunteers to occasionally report how many hours and how strenuously they were riding their bikes.
The researchers also tracked deaths among the group.
It turned out that the men and women who reported riding relatively hard (although none were racers) lived longer than those who rode at an easy pace, even if they weren't pedaling for as many hours. On average, cyclists who regularly rode hard lived about four or five years longer than those who went at a more leisurely pace.
"Our general recommendations to all adults would be that brisk cycling is preferable to slow," the authors conclude.
But not all researchers are convinced that intense exercise is essential, if your goal is a longer life. The general consensus among most researchers studying exercise and longevity "is that it is the total amount of energy expended that is important," and not whether you huff and strain during that expenditure, says Dr. I-Min Lee, a professor of medicine at Harvard Medical School, an author of a major new examination of exercise and life expectancy.
In that study, published last week in PLoS Medicine, Dr. Lee and colleagues from the National Cancer Institute and other institutions compiled physical activity, body mass and mortality data for more than 650,000 American adults who'd participated in National Cancer Institute studies over the years.
The researchers compared the volunteers' activity levels against the current governmental recommendation of 150 minutes of moderate activity (like brisk walking) per week. They found that those who met the recommendation lived on average 3.4 years longer than people who didn't exercise. Those who ambitiously doubled the recommended amount of weekly exercise enjoyed additional gains in life span, but at a noticeably diminishing rate, typically living 10 months or so longer than those who just met the guidelines.
Even people who were overweight or obese lived longer if they exercised moderately, whether or not they lost weight during the study period.
Interestingly, the association between physical activity and longer life held true also for those volunteers who reported exercising only occasionally. "A very low level of activity, equivalent to 10 minutes per day of walking, was associated with a gain of almost two years of life expectancy," says Steven Moore, a research fellow with the National Cancer Institute, who led the study.
In fact, he says, "maximum longevity was reached at a physical activity level equivalent to 65 minutes per day of walking, with no evidence for gains above this level of activity."
What all of this suggests, Dr. Lee says, is "that physical activity, even at a modest level, can increase life expectancy."
But it's also probable, although not yet definitively proven, she continues, that "intense exercise gives additional benefit above the risk reduction afforded by energy expenditure alone."
In other words, pushing yourself during your next walk, bike ride or home-repair project might amplify the activity's longevity-enhancing benefits, Dr. Lee says. But if you don't wish to or cannot increase the intensity of your exercise, don't sweat it.
The largest gain in terms of adding years to someone's life, she says, comes in that space between "doing nothing to achieving the lower end of the activity scale," which makes even the usually tedious prospect of washing this morning's breakfast dishes more palatable.