How much exercise we need to live longer

But at 10,000 steps, the benefits levelled off.

“There was a point of diminishing returns,” said Amanda Paluch, an assistant professor of kinesiology at the University of Massachusetts Amherst, who led the new study. People taking more than 10,000 steps per day, even plenty more, rarely outlived those taking at least 7000.

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Helpfully, the second study, which was published in August in Mayo Clinic Proceedings, settled on broadly similar activity levels as best bets for long life. This study involved data from the decades-long Copenhagen City Heart Study, which has recruited tens of thousands of Danish adults since the 1970s and asked them how many hours each week they play sports or exercise, including cycling (wildly popular in Copenhagen), tennis, jogging, swimming, handball, weightlifting, badminton and soccer.

The researchers focused on 8697 of the study’s Danes who had joined in the 1990s, noted their activity habits then, and checked their names against death records. In the 25 years or so since most had joined, about half had died. But those who reported exercising, in some way, between 2.6 and 4½ hours per week when they joined were 40 per cent or so less likely to have died in the interim than less active people.

Translating those hours of exercise into step counts is not an exact science, but the researchers estimate that people exercising for 2.6 hours a week, or about 30 minutes most days, likely would accumulate around 7000 to 8000 steps most days, between their exercise and daily life, while those working out for 4½ hours a week probably would be approaching the 10,000-steps threshold most days.

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At that point, as in the first study, benefits plateaued. But in this study, they then surprisingly declined among the relatively few people who worked out for 10 hours or more per week, or about 90 minutes or so most days.

“The very active group, people doing 10-plus hours of activity a week, lost about a third of the mortality benefits,” compared with people exercising for 2.6 to 4½ hours a week, said Dr James O’Keefe, a professor of medicine at the University of Missouri-Kansas City and director of preventive cardiology at the St. Luke’s Mid America Heart Institute, who was an author on the study.

Both studies are associational, though, meaning they show that physical activity is linked to life span but not that being more active directly causes life spans to lengthen.

Together, however, they provide useful takeaways for all of us hoping to live long and well:

• Both studies pinpoint the sweet spot for activity and longevity at around 7000 to 8000 daily steps or about 30 to 45 minutes of exercise most days. Doing more may marginally improve your odds of a long life, O’Keefe said, but not by much, and doing far more might, at some point, be counterproductive.
• Accumulate and measure your activities “in whatever way works for you,” Paluch said. “Step counting may work well for someone who does not have the time to fit in a longer bout of exercise. But if a single bout of exercise fits best with your lifestyle and motivations, that is great as well. The idea is just to move more.”

The New York Times

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