According to the fossil record, human beings began walking long distances about 1.89 million years ago, towards the end of the Pliocene epoch. It was only more recently, during the age of the Fitbit, that all able-bodied men and women were expected to take 10,000 steps a day. Now two studies, which together involved more than 20,000 Americans, have cast doubt on this target.

One study, involving more than 17,000 women between the ages of 62 and 101, showed the benefits of walking began to taper off after about 7,500 steps. Another study, involving a younger cohort of about 4,000 Americans, aged 40 and upwards, suggested there were health benefits from more steps but also showed those benefits dwindling before the 10,000-step mark.

Both studies note that the target probably derives not from hard science, but from a 1960s Japanese marketing campaign.

The Manpo-Kei Pedometer

“More is better but the curve levels off,” said I-Min Lee, a medical professor and epidemiologist at the Harvard School of Medicine, who was the lead author of the study on women. Dr Lee began looking at the ubiquitous 10,000-step target because she worried it was counterproductive for some people. “I became really interested in the origins of the 10,000 because I work with mainly older women,” she said. “With many older women, if you ask them for 10,000 steps it’s like asking them to go to the moon.”

Her paper reports that the yen for 10,000 steps “probably derives from the trade name of a pedometer sold in 1965 by the Yamasa Clock and Instrument Company”. Dr Lee said that the company sold a wearable pedometer that was called Manpo-kei, which meant “ten thousand step meter”.

“The Japanese character for 10,000 looks like a man walking, that’s why they chose it,” she said. “It wasn’t rooted in a scientific study.” Nor was there much study of the benefits of steps until the age of wearable fitness trackers. “We have always known that being active is good for you,” she said. “The more you do the better you are. The unknown is the steps issue.”

“The Japanese character for 10,000 looks like a man walking, that’s why they chose it.”

Before devices worn on the wrist such as the Fitbit, which was launched in 2007, “most research would be people talking about how much time they spent exercising”. Her study, published last year, showed that it was true that “the more you do the more benefit you get, but the curve tapers off at 7,500 steps,” Dr Lee said. “Women that did more than 7,500 didn’t get any extra benefit.”

The same did not necessarily apply to younger people, and her findings only applied to mortality, she said. The study did not show the effects of steps on various diseases, Dr Lee added. “But 10,000 was plucked out of the air.” The more recent study, of more than 4,000 Americans aged 40 and up, showed the benefits of more walking, all the way up to 12,000 steps. However, “the curve levels off,” Dr Lee said. “Even if you did less than 10,000, you still get a benefit.”

In a blog post Fitbit said that the starting goal of 10,000 steps “adds up to about five miles”, which would satisfy the weekly goals set by the US Centers for Disease Control. However, it acknowledged that the goal might not be right for everyone.