Its findings show that even small amounts of exercise contribute to substantial improvements in longevity and can lower risks of developing or dying of heart disease and many types of cancer.
“The investigators looked extensively at the available evidence and provided encouraging findings,” said I-Min Lee, a professor of epidemiology at Harvard T.H. Chan School of Public Health who was not involved in the new study.
Perhaps most inspiring, the study’s statistical analysis suggests that 1 in 10 of all early deaths might be averted if each of us got up and moved even a little more than many of us currently do.
150 minutes vs. 75 minutes a week
For years, governmental health agencies in the United States, Canada, Europe and other nations have recommended that anyone capable of exercising should exercise moderately for at least 150 minutes a week for optimal health. (Moderate exercise means a brisk walk or similar exertions that raise your heart rate and breathing enough that conversation becomes difficult.)
In practical terms, these guidelines promote walking briskly for half-an-hour five times a week.
But most of us don’t, according to the latest federal statistics, which show only about 47 percent of American adults exercise enough.
That sobering statistic prompted some researchers to begin looking into the effects of smaller amounts of exercise. Most of the resulting research, though, involved relatively small numbers of people, making broad conclusions about the best doses of exercise elusive.
So, for the new study, researchers at the University of Cambridge, Queen’s University Belfast and other institutions decided to aggregate data from as many relevant past studies as possible, creating a far larger pool of participants and potentially more-convincing results.
They wound up with 196 studies, covering more than 30 million people, making this by many measures and a hefty margin, “the largest” study of how exercise contributes to longevity, said Leandro Garcia. Garcia is a public health and complexity researcher at Queen’s University Belfast who led the new study.
Big gains from moving just a little more
What the aggregated data showed was that 150 minutes of moderate weekly activity should remain our exercise lodestar. People who managed that much exertion were about 31 percent less likely to die prematurely than inactive people.
But since two-thirds of the 30 million-plus participants did not exercise that much, the researchers also looked at the impacts of less movement. Bracingly, the impacts were big. Men and women who accumulated only 75 minutes a week of moderate exercise, or about 11 minutes a day, were 23 percent less likely to die prematurely from any cause than people who moved less.
Those 11 daily minutes of exercise also dropped people’s risks for heart disease by 17 percent and for cancer of any kind by 7 percent. For certain cancers, including myeloid leukemia, myeloma and some stomach cancers, the risk fell by as much as 26 percent.
Perhaps most compelling, the scientists also used statistical modeling to estimate that 16 percent, or 1 in 6, of all premature deaths would not happen if almost everyone exercised for 150 minutes a week, meeting the current guidelines.
Even if everyone walked just 11 minutes a day, 1 in 10 early deaths might be averted, they concluded.
“It was already known that doing some physical activity was better than doing none,” Garcia said. “However, because of the extensiveness of our study, we were able to establish this association more precisely.”
The study tells us that “the biggest bang for the buck comes when someone moves from doing nothing to doing even half the recommended levels” of exercise, Lee said.
Despite its size and rigor, though, the study has meaningful limitations. It shows correlations between more movement, longer lives and less disease, but not whether exercise directly causes those gains. Other factors, such as genetics and income, probably play large roles. The aggregated studies also relied on people’s memories and reports about how much they exercise, which can be unreliable.
But even with those drawbacks, the findings provide a helpful nudge, Garcia said. “Adding physical activity into your daily routine does not need to be daunting,” he said. “Small and gradual changes are a great starting point and will bring a range of health benefits.”
Park a little farther from your office, he said. Take the stairs. Dance around the living room with your kids.
Ideally, aim for about 11 minutes a day of moderate movement to start, he said, and if you find that amount “manageable,” then “try stepping it up gradually to the full recommended amount” of 150 minutes a week. But under any circumstances, he said, “doing some physical activity is better for your health than doing none.”
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