How Much Exercise Do You Really Need to Protect Against Disease?
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There’s a strong connection between physical activity and the risk of five common diseases, according to a study published today in The BMJ. The catch? To really reap the benefits, we need to move much more than global health experts currently recommend.
It’s no surprise that an active lifestyle may protect against a variety of health problems. But exactly how much and what type of activity is best is still up for debate, say the authors of the new study.
So they looked at the results from 174 previous studies that examined the association between total physical activity and at least one of five chronic diseases: breast and bowel cancer, diabetes, heart disease, and stroke. In these cases, physical activity meant all forms of movement—including exercise, housework and gardening, and active transportation like walking and cycling.
As suspected, they found that people who got the most total weekly physical activity were the least likely to develop all five of these conditions.
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But while the World Health Organization (WHO) currently recommends a minimum of 600 metabolic equivalent (MET) minutes a week across different “domains” of daily life, the study found that the most significant risk reductions occurred at levels much higher—around 3,000 to 4,000 MET minutes a week.
Yes, that’s a big difference. But don’t freak out just yet, the authors say. MET minutes aren’t equivalent to actual minutes; it’s a calculation that takes into account the intensity of the activity you’re doing. Jogging has a MET value of 7, for example, while walking the dog has a value of 3. A half hour of jogging, therefore, is equal to 210 MET minutes (7 x 30), while a half hour stroll with Fido (30 x 3) is only about 90.
So getting 3,000 MET minutes a week is easier than it sounds, especially if you incorporate different types of activity into your routine. For example, a typical day might include climbing stairs for 10 minutes, vacuuming for 15 minutes, gardening for 20 minutes, running for 20 minutes, and walking or cycling for 25 minutes.
In other words, move for an hour or two each day and you’ll be well on your way. “Getting 3,000 to 4,000 MET minutes a week may seem like quite a bit, but it is achievable when you focus on total activity across all domains of life,” says study co-author Hmwe Kyu, PhD, acting assistant professor of global health at the University of Washington. “If you are just more active by doing housework, taking the stairs, gardening, taking active transportation—these are things that are doable for most people, even if you can’t do intense exercise or go to the gym.”
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The study looked at observational results, which means it cannot prove a cause-and-effect relationship between physical activity and better health. And because it only considered total MET minutes, it wasn’t able to tell whether there were specific advantages to shorter, more intense workouts or longer, more moderate activity.
But the findings still have several important implications, according to the authors. First, the WHO’s recommendation for physical activity needs to be several times higher than it is currently, in order to see larger reductions in these five common diseases.
And second, they say, future research should pay more attention to total weekly activity—and not just leisure-time exercise, as many studies have done—to provide a better picture of how people can meet healthy activity goals in real-life settings.