U.S. fitness guidelines recommend at least 30 minutes of exercise five days a week. But increasingly, evidence suggests that even half that amount can extend significant health benefits.
Only about a third of Americans currently meet the Centers for Disease Control and Prevention’s (CDC) guidelines for physical health, which advise a minimum of 150 minutes of moderate exercise per week, plus additional strength-training.
Now here’s the good news for the rest of us: even just 15 minutes of moderate exercise a day (or 92 minutes per week) was associated with a three-year increase in life expectancy and a 14% reduction in risk of death by any cause, compared with a sedentary lifestyle, according to a new study.
Each additional 15 minutes of daily exercise (up to 100 minutes a day) reduced the risk of death by an additional 4%, the study found, and people who got 30 minutes of activity a day added about four extra years to their life expectancy, compared with their sedentary peers.
The observational study involved more than 400,000 people in Taiwan, who were followed for an average of about eight years. Researchers gave participants a questionnaire asking about their medical history and lifestyle habits, including how much leisure-time physical activity they got. Based on the answers, researchers divided them into activity intensity groups: light (walking), moderate (brisk walking), vigorous (jogging) and very vigorous (running).
People were characterized as inactive if they got less than one hour of exercise per week. Compared with this group, those who got even small amounts of moderate activity daily lived longer.
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“The 30-minute-a-day for five or more days a week has been the golden rule for the last 15 years, but now we found even half that amount could be very beneficial,” lead author Dr. Chi-Pang Wen told ABC News. “As we all feel, finding a slot of 15 minutes is much easier than finding a 30-minute slot in most days of the week.”
But that’s no excuse to scrape by with minimum effort. And it’s certainly no reason to scale back if you’re already working out for at least 30 minutes a day. When it comes to exercise, more is better. As anyone who has ever embarked on a new exercise regimen knows, the hardest part is starting; the longer you stick with it, the easier and more enjoyable it becomes. Over time, as you get fitter, your exercise goals will become easier to attain.
The new study had some limitations. For one, the questionnaires involved self-report, which always carries a measure of inaccuracy. The study was also observational, so it’s not clear whether people’s health outcomes could be attributed to factors other than exercise (though the researchers accounted for other factors like smoking, drinking, cholesterol levels, blood pressure and history of disease), or whether it was inactivity that caused poor health or vice versa.
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Still, there is no shortage of existing evidence that increasing physical activity leads to all-around improvements in health, mood and well-being. And the new results suggest that even small amounts of moderate exercise — think biking, walking briskly or dancing — may mean significant benefits.
“The knowledge that as little as 15 minutes per day of exercise on most days of the week can substantially reduce an individual’s risk of dying could encourage many more individuals to incorporate a small amount of physical activity into their busy lives,” wrote Dr. Anil Nigam and Dr. Martin Juneau of the Montreal Heart Institute and the University of Montreal in an accompanying editorial in The Lancet, which published the new study online on Aug. 15.
Meredith Melnick is a reporter at TIME. Find her on Twitter at @MeredithCM. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.