We've all heard the advice to take 10,000 steps a day, but is that precise number really necessary to reap health rewards?
The optimal number may be much less dependent on your age, new research suggests. Women whose step counters reached 4,400 each day had a 41% lower rate of death than women who took 1,700 fewer steps each day, a new study of older women found.
"That's a very modest number of steps. Almost anyone can do that," said I-Min Lee, lead author of the new study and an epidemiologist in the Division of Preventive Medicine at Brigham and Women's Hospital in Boston.
She added that her interest in step counters led her to search for the origins of the oft-quoted "10,000 steps for better health" advice. The earliest mention was dated 1965 and traced back to a Japanese company that made pedometers. "They called their pedometer a Manpo-kei, which in Japanese means a '10,000 steps meter," she said.
"That number was less based on science than on marketing purposes," she added. JAMA Internal Medicine published her study on Wednesday.
New and improved research methods
The average number of steps taken by American adults is between 4,000 and 5,000 per day, previous research shows.
Yet past studies have relied on self-reporting, "an individual's recall of what they did," explained Lee. "Nowadays, with the advent of wearables, including research-grade wearables, we are able to measure physical activity more precisely."
She and her colleagues collected data from nearly 17,000 women, at an average age of 72, who for seven days wore on their hips (the preferred placement for a step-counting device) research-grade accelerometers, a device for measuring both motion and speed. Next, the researchers tracked the women for four years or longer. During this time, 504 of the women died.
An analysis of the data showed that of these deaths, 275 were in the group of least active participants and averaged just 2,700 steps each day. This low activity group proved to be at the highest risk of death, the study showed. Compared to this group, the women who averaged 4,400 steps per day had a 41% lower rate of death, noted Lee. Taking more steps each day lowered risk of mortality even more, she said: "Until about 7,500 steps and then it sort of leveled -- meaning if you took more steps than that, it didn't help you anymore."
"So for women who are not active or thinking about being active, just a modest number of steps a day can help your health," she said.
"The second question we asked was: Does it matter whether your steps are fast or slow?" she said. Turns out "it didn't matter whether you were stepping faster or slower, it was the number of steps that actually counted," she explained.
She emphasized that her study only looked at mortality rates so it's not clear whether more steps -- 10,000, say? -- might offer additional health benefits, such as better cognitive health or daily function. She hopes to study this in the future, she said.
As for now, she believes the new results would probably apply to same-aged older men because "we know the relation between physical activity and different health outcomes appear similar between men and women." She's not sure, though, that the findings would apply to all age groups. "For a younger age group, it might take more steps," she said.
Motivation to move more
Dr. Kaberi Dasgupta, a practicing physician and professor of medicine at McGill University, told CNN in an email that the new study was "well-done" and the average period of follow-up, four years, "was reasonable."
While the large number of participants means subtle differences could be detected, the fact that only women participated in the research means "we don't know if the results apply to men," said Dasgupta, who was not involved in the study.
Her own work looked at hundreds of patients with type 2 diabetes or high blood pressure; some were randomly chosen to receive a "step count prescription" from their doctors each visit, while others did not. At the end of a year, those with a step count prescription increased their daily steps by 1,200 more than the other group, she said: "They also had better blood sugar control."
"We have too many options that keep us sitting. We can work, shop, and entertain ourselves from small and large screens," she said. Though technology encourages us to sit, it can also be used to help us to walk, she added.
"We need to figure out ways to keep ourselves motivated and make healthy behaviour a habit," she wrote. "Whether it's a step count prescription from a doctor, an on-line group where you track steps, or a friendly competition at the workplace -- all can help you have a longer and healthier life."
Steven Blair, a professor emeritus at the University of South Carolina, told CNN in an email that major strengths of the new study include "objectively measured physical activity" and a conclusion that specified an exact number of steps per day.
Blair, who was not involved in the new study though he's done his own similar research, said that inactivity is the "biggest public health problem of the 21st century." One of the study's most important findings, then, is "the value of doing at least some activity and it does not need to be at a high intensity," he said.
In Lee's words: "If you do nothing, do something. Get your steps up to 4,500 and you will start seeing benefits. For people who are willing to do more, by all means."
"And if it makes you feel good to do 10,000 steps versus 7,500, I say, 'Go for it!' "