Kent Peterson, senior editor, has also produced award-winning work in television and radio.

You’ve heard it again and again: exercise is good for you. But how good exactly? New evidence suggests physical activity may have much greater benefits than most people think.

A large study of older women found those who were most active had a 60 to 70 percent lower risk of death compared to those who were least active.

Past studies have found a 20 to 30 percent lower death rate in people who exercise—still worthwhile, but hardly as dramatic. The new study’s results even surpassed the roughly 50 percent mortality reduction that comes from quitting smoking.

Better evidence

The findings of this new study are especially compelling because the quality of its data is superior. In most activity studies, people are asked to remember how much they exercised and report it, leaving plenty of room for error. But in this study, participants wore a sensitive professional-quality device that measured every movement.

“We used devices to better measure not only higher-intensity physical activities, but also lower-intensity activities and sedentary behavior,” said I-Min Lee, MBBS, ScD, in a news release. He is the study’s first author and professor of medicine and epidemiology at Harvard University’s medical and public health schools.

About 17,000 relatively healthy women, whose average age was 72, took part. They wore the device during their waking hours for a week as they went about their usual daily routines. The most active women, who got the greatest benefit, spent an average of nearly 70 minutes a day engaged in moderate to vigorous activities. The least active women had only eight minutes of activity a day.

Next, individuals were followed for an average of about two and a half years to monitor their mortality. By the study’s end, 207 had passed away.

What mattered—and what didn’t

Two things were linked to the greatest reduction in death risk: doing more intense activities and doing them longer.

This didn’t require exercises that are too strenuous for most older people. The moderate to vigorous activities that helped included such things as brisk walking—no marathon races needed.

Light-intensity activities, such as walking slowly or doing housework, didn’t reduce death risk no matter how many were done. Researchers stress that light activities may still have other health benefits that were not studied in this trial.

Surprisingly, researchers didn’t find that increasing sedentary behavior made death risk go up—only that more activity made it go down.

The bottom line

This kind of study can’t prove cause and effect, and the findings might be different for men or people of other ages. Still, it’s encouraging to see evidence of such enormous possible benefits from modest exercise.

“What is irrefutable is the fact that physical activity is good for your health,” Lee said.

To be safe, check with your doctor before starting any new fitness regimen.

Be active, feel your best, and maybe live longer too. The effort is worth it!

What do you do to stay fit? Share your advice by adding a comment below.