Wearables, such as Fitbits, track steps and are more popular than ever with over 125 million shipped in 2017. Most wearables default to 10,000 steps per day even though the origin of this goal is unclear and there is no scientific research to support this arbitrary step count.
Dr. I-Min Lee and colleagues ran a prospective cohort study of almost 17,000 older women (mean age, 72) from 2011 to 2015. Participants wore an activity monitor, while awake, for 7 days. The monitors tracked steps per day and stepping intensity. The researchers then linked these data to a subsequent 5 years’ worth of mortality data from death certificates or the National Death Index.
After adjusting for potential confounders such as age, smoking, and family history of early heart attacks and cancer, the authors found that women who moved the least, about 2,700 steps per day, were the most likely to die in the follow-up period. Women who moved more had a lower risk of death, up to a plateau of about 7,500 steps per day.
An average of 4,400 steps per day was associated with a 40% lower risk of mortality compared with those who took 2,700 steps per day. Stepping intensity did not matter in this study.
In a New York Times article, Dr. Lee noted that:
We were quite surprised that such a relatively small number of steps would be associated with such a substantial reduction in mortality.
Lee, I. M., Shiroma, E. J., Kamada, M., Bassett, D. R., Matthews, C. E., & Buring, J. E. (2019). Association of Step Volume and Intensity With All-Cause Mortality in Older Women. JAMA internal medicine.
