A new study involving nearly 50,000 people from four continents offers new insights into identifying the quantity of daily walking steps that will best improve adults' health and longevity(长寿), and whether the ideal number of steps differs across people of different ages. The study represents an effort to develop an evidence-based public health message about the benefits of physical activity. The often-repeated 10,000-step-a-day saying grew out of a decades-old marketing activity for a Japanese pedometer(计步器), with no science to back it up.

Led by physical activity professor Amanda Paluch, an international group of scientists conducted an experiment among adults aged 18 and older. They grouped the nearly 50,000 participants into four comparative groups according to average steps per day. The lowest step group averaged 3,500 steps; the second, 5,800; the third, 7,800; and the fourth, 10,900 steps per day. Among the three higher active groups, there was a 40—53% lower risk of death, compared to the lowest step group. 

More specifically, for adults 60 and older, the risk of early death leveled off at about 6,000—8,000 steps per day, meaning that more steps than that provided no additional benefit for longevity, while for adults younger than 60, about 8, 000—10,000 steps per day. 

"So, what we saw was this continuing reduction in risk as the number of steps increases, until it levels off. Interestingly, the study found no definitive association with walking speed." Paluch says.

The new study supports and expands findings from another study led by Paluch before, which found that walking at least 7,000 steps a day reduced middle-aged people's risk of early death. "There's a lot of evidence suggesting that moving even a little more is beneficial, particularly for those who are doing very little activity." Paluch says. "More steps per day are better for your health."