How much exercise do we have to do to live longer?

Gretchen reynolds

09/17/2021 19:09

• Clarín.com

• The New York Times International Weekly

Updated 09/17/2021 19:09

To increase our chances of living a long life, we should probably take at least 7,000 steps a day or do sports like tennis, cycling, jogging or badminton for more than

2.5 hours a week

, according to two new large-scale studies on the relationship between physical activity and longevity.

These studies, which together followed more than 10,000 men and women for several decades, show that certain physical activities in adequate amounts

reduce the risk of

premature

death by

up to

70 percent.

People exercise along Las Ramblas in Barcelona.

Photo by PAU BARRENA / AFP.

But they also suggest that when it comes to longevity, there may be an

upper limit

to the benefits of being active, and exceeding that threshold will most likely not add years to our lives, and even in extreme cases could be detrimental.

Much research has already suggested that people who are active live longer than those who rarely engage in physical activity.

For example, a 2018 study by the Centers for Disease Control and Prevention (CDC) found that about 10 percent of all deaths among Americans ages 40 to 70 are the result of very little physical activity.

A 2019 European study found that two decades of inactivity doubled Norwegians' risk of dying young.

But scientists have not yet been able to pin down how much movement, or how little, could be related to increased longevity.

It is also unclear if there is

too much exercise

that could contribute to a shorter life span.

Those issues lie at the center of two new studies that examine the relationship between physical activity and longevity from angles that, while different, are intertwined.

The first of these studies, published this month in JAMA Network Open, focused on the steps that participants took.

Most of us are familiar with counting daily steps as an exercise goal, since many phones, smartwatches, and other activity trackers urge us to take a certain number of steps every day, often

10,000.

But, as I have detailed previously, current science has not shown that we need to take 10,000 steps to live a long or healthy life.

Researchers at the University of Massachusetts at Amherst, the CDC, and other institutions wondered whether fewer steps in total could also lead to a longer life.

So they turned to data collected in recent years in a large ongoing study of heart health and disease in middle-aged men and women.

Most of the participants had entered the study about 10 years earlier, when they were 40 years old.

At the time, they underwent medical evaluations and wore an activity tracker to count their steps every day for a week.

The researchers then extracted the records of 2,110 of the participants and matched their names against death records.

They found that 72 had died in the past decade, a small number that is not surprising given the relative youth of the people.

But the scientists also observed a

close relationship

between the number of steps and mortality.

Men and women who accumulated at least 7,000 daily steps when they entered the study were 50 percent less likely to have died than those who took fewer than 7,000 steps, and mortality risks continued to decline as the number of steps increased. steps, leading to a 70 percent lower chance of premature death among those who took more than 9,000 steps.

But after 10,000 steps, the benefits

stabilized.

"There was a point of decline in benefits," said Amanda Paluch, associate professor of kinesiology at the University of Massachusetts, Amherst campus, who led the new study.

People who take more than 10,000 steps a day, or even many more, rarely lived longer lives than people who took at least 7000 steps.

Fortunately, the second study, published in May in the

Mayo Clinic Proceedings

, found very similar activity levels as the best bet for a long life.

This study used data from the Copenhagen City Heart Study, which has recruited tens of thousands of Danish adults since the 1970s and asks them how many hours a week they play sports or exercise, including cycling (very popular in Copenhagen), tennis, jogging, swimming, handball, weightlifting, badminton and soccer.

The researchers focused on 8697 Danes in the study who had enrolled in the 1990s, recorded their activity habits back then, and checked their names against death records.

In the 25 years since most had enlisted, about half had died.

But those who reported exercising some 2.6 to 4.5 hours a week when they entered the study were 40 percent less likely to have died in that period than less active people.

Translating those hours of exercise into a number of steps is not an exact science, but researchers estimate that people who exercise for 2.6 hours a week, or about 30 minutes most days, would likely accumulate between 7,000 and 8,000 steps per day, between exercise and your routine activities, while those who exercise for 4.5 hours a week would likely approach the 10,000 step threshold most days.

At that point, the same thing happened as in the first study and the benefits stabilized, but with the difference that in this study,

surprisingly

, those benefits decreased among the few people who exercised

for 10 hours or more a week

, or a few 90 minutes or so most days.

"The very active group, people who exercised 10 hours or more per week, lost about a third of their mortality benefits compared to those who exercised 2.6 to 4.5 hours per week," said James O'Keefe, a professor of medicine at the University of Missouri-Kansas City and director of preventive cardiology at the Heart Institute at St. Luke's Mid America Hospital, who was one of the study's authors.

However, both studies are

associative

, that is, they show that physical activity is related to the duration of life, but not that being more active directly causes a longer life expectancy.

Either way, together, the studies provide useful information for all of us who want to live long and well:

- Both studies indicate that the sweet spot for activity and longevity is around 7,000 to 8,000 steps a day or 30 to 45 minutes of exercise almost every day.

Doing more can marginally improve your chances of a long life, O'Keefe says, but not by much, and doing a lot more could, at some point,

backfire.

- Accumulate and measure your activities "in the way that works for you," said Paluch.

“Step counting can work well for someone who doesn't have time for a longer exercise session.

But if a single exercise session better suits your lifestyle and interests, that's fine too.

The idea is just that you move more ”.

c.2021 The New York Times Company

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