New research points to different step counts based on age and fitness level.
By Lydia Denworth on
In 2022 I averaged 9,370 steps a day. I know. I counted. Or rather my iPhone counted. I carried it everywhere—not so much to catch every call as to catch every step. My daily aim? Ten thousand steps. Because goals.
Yet the concept of taking 10,000 steps a day to maintain health is rooted not in science but in a marketing gimmick. In the 1960s a company in Japan invented an early pedometer. Because the Japanese character for “10,000” looks like a person walking, the company called its device the 10,000-step meter.
“It was just sort of a catchy phrase,” says I-Min Lee, an epidemiologist at Harvard Medical School and Brigham and Women's Hospital in Boston. Taking that many steps daily is challenging but doable for many people. “Sure, if you get 10,000 steps, it seems like a good goal. But there was not really any basis to it.”
Step-counting devices such as watches and phones came into widespread use only in the past two decades. Once they did, scientists needed to follow users for long periods to learn anything meaningful about the number of steps that affects mortality, cardiovascular fitness or anything else. And until recently, that hadn't happened.
The current physical activity guidelines from the U.S. Department of Health and Human Services, published in 2018, are still based on time. Experts reviewed hundreds of studies on exercise and health. Nearly all were based on self-reports of physical activity, a measure that is not exact. It's the equivalent of guessing how much time I spent walking last year.
Because of that room for error, the experts ended up recommending broad exercise ranges and not step counts: 150 to 300 minutes of weekly moderate activity (the equivalent of brisk walking) or 75 to 150 minutes of vigorous activity (for example, jogging) during the same period. A decade of consistently hitting that goal translates to about an extra year and a half of life, epidemiological studies indicate. There simply wasn't enough evidence to make a similar determination about steps. “It killed me that we couldn't,” says William Kraus, a physician and scientist at Duke University, who helped to draw up the guidelines. “Step counts are accessible. People can understand them.”
Now evidence about steps is starting to come in. In 2019 Lee published one of the first studies specifically investigating the actual effects of meeting the 10,000-step goal. Several other large studies followed. The result? Some movement is good, and more is better, but the benefits taper at some point. Your personal peak depends on your age. People younger than 60 should indeed walk 8,000 to 10,000 steps a day to get the best benefits in terms of life expectancy and cardiovascular health. People older than 60 show the most benefit between 6,000 and 8,000 steps. (Seven thousand to 9,000 steps a day is roughly equivalent to 150 to 300 minutes of brisk walking each week, the target in the 2018 guidelines.)
The difference is energy expenditure. “We basically relate energy expenditure to health outcomes,” Kraus says. Walking for 60 minutes at 3.3 miles an hour and running for 30 minutes at six miles an hour use the same amount of energy. “The older you are, the less efficient you are with your steps,” Kraus says. “Per step, older people expend more energy.” As a result, they need fewer steps to achieve the same benefits.
Adding a few thousand steps a day can be especially meaningful for someone who isn't physically able to walk briskly, says Amanda Paluch, an epidemiologist at the University of Massachusetts Amherst, who led two meta-analyses linking step counts with risk of death and cardiovascular disease. She concludes that “the people who are the least active have the most to gain.”
The total number of steps you take does appear to matter more than the speed at which you take them. “The relevant question for me is, When two people walk the same amount, does it matter whether their steps are accumulated at a faster rate versus a slower rate?” Lee says. The answer so far is no.
Newer studies are moving beyond death rates to ask questions about the way steps may contribute to diabetes prevention or help to control blood pressure and weight. The goal, after all, is not just to live longer but to live healthier. Full results are not in yet, so Lee's advice in the meantime is: “Tailor your steps according to what you are trying to achieve and according to who you are.”
ABOUT THE AUTHOR(S)
Lydia Denworth is an award-winning science journalist and contributing editor for Scientific American. She is author of Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond (W. W. Norton, 2020) and several other books of popular science.
(Sources: Scientific American)
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