A New Magic Number for Tracking Steps.

• Position: YOUR LIFE

In the world of step goals and activity trackers, the number 10,000 can sound like a magic one. A large body of evidence shows that physical activity is good for health and longevity, and many wearable devices that track the steps a person takes each day come preprogrammed with a daily goal of 10,000--but few studies have examined how many steps a day are associated with long-term health outcomes.

A study led by investigators from Boston's Brigham and Women's Hospital sought to address this knowledge gap by examining outcomes over an average of more than four years for older females in the Women's Health Study.

The team reports that, among this cohort, as few as 4,400 steps a day was significantly associated with lower risk of death compared with taking 2,700 steps a day. Risk of death continued to decrease with more steps taken, but leveled off at around 7,500 steps a day--less than the default goal in many wearables. The team's results were presented at the American College of Sports Medicine's annual meeting and published in JAMA Internal Medicine.

'Taking 10,000 steps a day can sound daunting, but we find that even a modest increase in steps taken is tied to significantly lower mortality in older women," says I-Min Lee, epidemiologist in the Division of Preventive Medicine at Brigham. "Our study adds to a growing understanding of the importance of physical activity for health, clarifies the number of steps related to lower mortality, and amplifies the message 'step more.' Even a little more is helpful."

According to previous studies, the average American takes between 4,000 and 5,000 steps a day. The origin of the 10,000-step goal is unclear, but may trace back to 1965, when a Japanese company began marketing a pedometer called Amanpo-Kei, which translates to "10,000 steps meter" in Japanese.

To conduct their study, Lee and her colleagues included participants from the Women's Health Study, a randomized trial originally conducted to evaluate risk of cardiovascular disease and cancer among women taking low-dose aspirin and vitamin E. When the original trial ended, participants...