Do we need to walk 10,000 steps a day?
Many of us track our steps with smart watches, pedometers or phone apps and are of course thrilled when we reach that all-important daily goal of 10,000 steps. With the app I use, green confetti tumbles down the screen in congratulation. The app logs “strikes”, too, challenging me to see how often I can manage a week-long stretch above 10,000 steps a day. Answer: rarely.
There are debates over the accuracy of some step-counters and it’s obvious that they’re a blunt instrument in terms of measuring exercise. If you sprint, your score is no higher than if you dawdle, yet there’s a real difference in terms of benefits to fitness. Still, they do provide a rough guide to how active you’ve been.
If you are going to count steps, the magnitude of your goal matters. Most tracking devices are set to a default goal of 10,000 steps – the famous number that we all know we should reach. You might assume that this number has emerged after years of research to ascertain whether 8,000, 10,000 or maybe 12,000 might be ideal for long-term health. In fact, no such large body of research exists.
The magic number “10,000” dates back to a marketing campaign conducted shortly before the start of the 1964 Tokyo Olympic Games. A company began selling a pedometer called the Manpo-kei: “man” meaning 10,000, “po” meaning steps and “kei” meaning meter. It was hugely successful and the number seems to have stuck.
Since then, studies have compared the health benefits of 5,000 versus 10,000 steps and, not surprisingly, the higher number is better. But until recently, all the numbers in between hadn’t been studied. Even now they haven’t been comprehensively tested on the general adult population. New research from I-Min Lee, a professor of medicine at Harvard Medical School, and her team focused on a group of more than 16,000 women in their seventies, comparing the numbers of steps taken each day with the likelihood of dying from any cause – known as all-cause mortality. Each woman spent a week wearing a device to measure movement during waking hours. Then the researchers waited. 纽约时报中英文网 http://www.qqenglish.com
When they followed the women up an average of four years and three months later, 504 had died. How many steps do you think the survivors had been doing? Was it the magic 10,000 steps a day?
In fact, the average number for survivors was only 5,500 – and incremental gains in steps mattered. Women who took more than 4,000 steps a day were significantly more likely to still be alive than those who did only 2,700 steps. It’s surprising that such a small difference could have consequences for something as critical as longevity.
By that logic, you might assume the more steps they took, the better. For a range of steps that was true – but only up to 7,500 steps a day, after which the benefits then plateaued. Any more than that made no difference to life expectancy.
Of course, one drawback of this study is that we can’t be certain that the steps preceded the illness that killed them. The researchers only included women who were fit enough to walk outside their home and they did ask people to rate their own health, but perhaps there were some participants who were well enough to walk, but already not well enough to walk very far. In other words, they walked less steps because they were already unwell, and the steps themselves made no difference.
But for this age group, this study suggests that maybe 7,500 is enough – although it’s possible that extra steps could confer additional protection against specific conditions. The higher step count could also have been an indicator of women who had generally been more active throughout their lives, and it was this that helped them to live longer. For this reason, it is hard to unravel the exact health benefits of extra steps alone.
Then there’s the question of the optimum step count in psychological terms. The 10,000 target can seem like a high goal to achieve every single day, which might tempt you not to bother. Consistently failing to achieve your goal day after day is dispiriting. In a study of British teenagers, at first the 13 and 14-year-olds enjoyed the novelty of being given the target, but they soon realised how difficult it was to maintain and complained that it wasn’t fair.
I’ve done my own psychological experiment on myself by changing the default goal on my app to 9,000 steps. I kid myself that I do the other thousand walking around at home when I’m not carrying my phone, but in truth I just want to encourage myself by succeeding more often.
To raise the step count of the most sedentary, a lower goal might be better psychologically.
But even then, counting steps at all risks robbing us of the intrinsic pleasure of walking. Jordan Etkin, a psychologist at Duke University in the US, found that people who tracked their steps did walk further, but they enjoyed it less, saying it felt like work. When they were assessed at the end of the day, their happiness levels were lower than in those who had walked without their steps being tracked.
不顾一切只为完成步数，这会剥夺我们走路时的乐趣。美国杜克大学（Duke University）心理学家埃特金（Jordan Etkin）发现，记录自己步数的人确实走得更远，但他们并不那么喜欢走路，感觉像是在完成一项工作。当一天结束评估时，他们的快乐指数比那些没有记录的人要低。
Counting steps might be counterproductive for the fittest too – signalling that they should stop once they’ve reached the magic 10,000 instead of getting fitter by, say, doing more.
What can we conclude from all of this? Count if you find it motivates you, but remember there’s nothing special about 10,000 steps. Set the goal that is right for you. It might be more, it might be less – or it might be throwing out your tracker entirely.