Association of Step Volume and Intensity With All-Cause Mortality in Older Women

Association of Step Volume and Intensity With All-Cause Mortality in Older Women
I-Min Lee, MBBS, ScD1,2; Eric J. Shiroma, ScD3; Masamitsu Kamada, PhD4; David R. Bassett, PhD5; Charles E. Matthews, PhD6; Julie E. Buring, ScD1,2
Article Information
JAMA Intern Med. Published online May 29, 2019. doi:10.1001/jamainternmed.2019.0899


1 Such wearables, as well as smartphones, measure number of steps taken via an accelerometer within the device. Worldwide, the average number of steps accrued daily (measured by smartphones) is approximately 5000; in the United States it is 4800.2 A common goal of 10 000 steps/d has been perpetuated by the lay press and is often used as the default by software programs on wearables and smartphones.3,4 However, the origin of the goal of 10 000 steps per day is unclear. It likely derives from the trade name of a pedometer sold in 1965 by Yamasa Clock and Instrument Company in Japan called Manpo-kei, which translates to “10 000 steps meter” in Japanese.5,6

7-13particularly as related to clinical end points and mortality.14-17 Additionally, steps walked can be slow or fast, and it is unknown how stepping intensity is associated with health18 (though there are data on walking pace,19 a related but not identical concept20). An expert committee recently identified a critical gap in knowledge on the dose-response association of steps with health outcomes.18 The 2018 Physical Activity Guidelines Advisory Committee, in a scientific report underpinning the second edition of physical activity guidelines for Americans,18 explained why this information is important: “Steps are a basic unit of locomotion and as such, provide an easy-to-understand metric of ambulation.”18(p8) Furthermore, “…steps can be at light-, moderate-, and vigorous-intensity levels, providing a range of exertion choice to promote walking at all ages and for all levels of fitness. For these reasons, the measure of steps per day has the potential to significantly improve the translation of research findings into public health recommendations, policies, and programs.”18(p8)

21-23 When the trial ended, women were invited into an observational study, and 33 682 (89% of survivors) consented.

24 Briefly, 18 289 women (62% of survivors) agreed to participate and were eligible; of these, 17 708 subsequently wore and returned their devices. Data were downloaded successfully from the devices of 17 466 women (no data were available from 242 women owing to device failure). All women provided written informed consent to participate, and the study was approved by the Brigham and Women’s Hospital’s institutional review board committee.