Confused about how much exercise you need each week to be healthy? You’re not alone. A new Duke study is providing insight that may help.
The research—led by William Kraus, professor of medicine at the School of Medicine—found that whether exercise was sustained or sporadic, it offered the same benefits in reducing mortality over a given period.
“For this study, we were interested in studying short bouts of moderate to vigorous activity to see whether they would offer the same benefits in terms of reducing risk of chronic conditions like diabetes, heart disease and death,” Kraus wrote in an email.
In the past 30 years, guidelines have said that moderate to vigorous activity could improve health, but only if the activity was done for 10 minutes or more. However, this new research revealed that even short bursts of activity like walking up and down stairs can be beneficial, as long as the intensity is at a moderate or vigorous level.
For most people, an example of moderate exercise would be walking at a speed that makes it difficult to have a conversation, while vigorous exercise includes activities like jogging.
Kraus and researchers from the National Cancer Institute used data from the National Health and Nutrition Examination Survey between 2003 and 2006. In particular, they looked at 4,840 people 40 and older who had worn accelerometers for the survey to measure their physical activity and exertion. In 2011, 4,140 of the participants were still living.
They found that the participants who did less than 20 minutes of moderate or vigorous activity each day had the highest risk of dying during the study. Those who received 60 minutes per day reduced their risk of death over a 10-year period by 57 percent and those who did 100 minutes cut the risk by 76 percent.
“We were able to look at increments as small as one minute and found that it’s the accumulated amount of time that you’re getting this activity each day and each week that lead to health benefits, in this case, death over a 10-year period,” Kraus noted.
He explained that it doesn’t matter whether you get that activity in short sessions of a few minutes at a time—it all adds up, and when you can get at least 30 minutes most days of the week, you’re going to see a reduced risk of death in the next 10 years.
“Those who benefit most are people who have been sedentary and start exercising—they’re going to cut their death risk by more than half,” he noted. “Those who are more active will still see increased benefit. And the great news, more is even better.”
So what does Kraus recommend for people trying to make time for exercise in their busy schedules?
He emphasized the importance of incorporating physical activity throughout the day by taking the stairs or setting a goal to move every hour.
The U.S. Department of Health and Human Services guidelines currently recommend at least 150 minutes of moderate exercise or 75 minutes of vigorous activity each week. Kraus hopes that the updated guidelines—expected to be released later this year—allow these less time-intensive activities to count toward a new recommendation of 150-300 minutes total of moderate to vigorous physical activity each week.
His personal advice for his patients is to track their steps and to get at least 10,000 a day.
“It’s pretty hard to get to 10,000 steps in a day around a full workday without going for at least a walk, a jog or other form of purposeful moderate-intensity activity,” he said. “I believe if people set this as a goal, they’re going to get the minimum recommended exercise in a week.”
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