A new study says you need 10 hours of exercise a week. Can that really be possible?

A new study says you need 10 hours of exercise per week. Is this really possible?

By Claire Cameron edited by Seth Fletcher

A study published this week in the British Journal of Sports Medicine suggests that the average adult should aim to get around nine to 10 hours of exercise per week – well above the World Health Organization (WHO) recommendation of 150 minutes per week – to see a substantial reduction in their risk of stroke or heart attack. But some cardiovascular disease and fitness experts say this new research should be approached with a healthy dose of caution.

The study authors “downplay the benefits of physical activity,” says Sean Heffron, an assistant professor of medicine and cardiologist specializing in exercise science at New York University.

The study analyzes accelerometer data collected over the course of a week from 17,000 people included in the UK Biobank, a long-term health study. It appears that for the average person to experience a 30 percent reduction in risk of stroke or heart attack, they need to engage in approximately 560 to 610 minutes of moderate to vigorous physical activity per week. And less fit people might need to exercise up to 50 minutes more than fitter people to get the same benefits, the study found.

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For comparison, the WHO guidelines of 150 minutes of moderate exercise per week are associated with an 8 to 9 percent risk reduction. That’s no small thing, Heffron said. “If we found a new drug that improved the risk that much, we would be thrilled,” he says.

The results do not indicate that the WHO exercise guidelines are wrong, Heffron says. They also don’t suggest that short, high-intensity exercise sessions, such as high-intensity interval training, aren’t also associated with large reductions in cardiovascular disease risk, says Ulrik Wisløff, a professor at the Norwegian University of Science and Technology who leads the university’s cardiac exercise research group.

“The 150-minute recommendation was never intended to represent an ‘optimal’ goal,” says Wisløff. “Rather, it was designed as a realistic and achievable public health threshold, associated with significant population health benefits. »

The study design also risks obscuring the relative intensity of physical activity for different individuals, says Wisløff. An older person, for example, might consider the same task, say a walk around the block, to be vigorous exercise, while a younger, fitter person might not consider it exercise at all.

In turn, many people may underestimate the amount of exercise they already get, says Heffron. Moderate walking, tennis, gardening, or any other activity that possibly makes you sweat counts as vigorous activity. “The gym does not have a monopoly on physical exercise,” he says.

Wisløff agrees, emphasizing that the health effect of any type of activity depends on its intensity. He cites previous studies that showed that even five minutes a day of moderate to vigorous physical activity could reduce the risk of mortality by about 30 percent in people who did not otherwise exercise. “Small amounts of relatively intense activity seem extraordinarily powerful,” he says.

Genetics also play a role in fitness that the study simply can’t account for, Heffron says. And the study only includes one week of data: It’s entirely possible that participants exercised more than usual during that week, which would complicate the results. And as for the finding that less fit people have to do more to get the same benefits, Heffron says that “as a clinician, I would completely ignore that.”

“Your individual health and longevity is not a competition,” he says. “We believe exercise is beneficial for multiple reasons, and we cannot determine who will benefit most.”

“It is clear that no activity puts you at significantly increased risk [of conditions such as diabetes and hypertension]”, he adds. “Going from zero to anything on an individual basis can be helpful. “

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