02 Jun Mortality: Number of Steps Matter, Up To a Point
MedicalResearch.com Interview with:
I-Min Lee, MD, ScD
Professor of Medicine, Harvard Medical School
Professor of Epidemiology
Harvard T.H. Chan School of Public Health
MedicalResearch.com: What is the background for this study?
Response: While we have many studies showing that physical activity is beneficial for health, there are few data on steps and health, particularly long-term health outcomes. An expert committee – the 2018 Physical Activity Guidelines Advisory Committee, which reviewed the scientific evidence to support the recently released Physical Activity Guidelines for Americans, 2nd edition – noted this (i.e., the relation between steps and health outcomes) to be a critical gap in knowledge, since many individuals are using wearables and monitoring their step counts.
We often hear the number 10,000 steps cited as a daily goal, but the basis for this number is unclear. It likely originated as a marketing tool: in 1965, the Yamasa Clock and Instrument Company, Japan sold a pedometer called “Manpo-kei” – “ten thousand steps meter” in Japanese.
For many older people, 10,000 steps/day can be a very daunting goal; thus, we wanted to investigate whether this was necessary for lower mortality rates in older women. Additionally, steps taken can be fast or slow, and there are no published studies on step intensity and long-term health outcomes. Note that walking pace and step intensity are not the same concept: walking pace gauges intensity when walking purposefully (e.g., for exercise or transportation), while step intensity assesses an overall best natural effort in our daily life.
MedicalResearch.com: What are the main findings?
Response: In this study, conducted among older women with mean age of 72 years, taking as few as 4,400 steps per day was significantly associated with lower risk of death compared to taking 2,700 steps per day. Risk of death during follow-up continued to decrease with more steps taken but leveled off at around 7,500 steps per day — less than the 10,000 steps default goal in many wearables. The rate of stepping did not matter in these older women; it was the number of steps taken that mattered.
MedicalResearch.com: What should readers take away from your report?
Response: Step more – even a modest amount of steps is associated with lower mortality. In this study, women who averaged 4,400 steps/day – a very doable level – had a lower mortality rate during follow-up than the least active who took 2,700 steps/day. More steps taken per day were associated with even lower mortality rates until ~7,500 steps/day, beyond which no further declines were observed. The rate of stepping did not matter in these older women; it was the number of steps that mattered. We hope these findings provide encouragement for individuals for whom 10,000 steps a day may seem unattainable
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: This study was conducted among older women, who were not very active and in whom there was little fast stepping. Thus, findings may be different in younger and/or more active persons – we would need to conduct further studies. Additionally, we only investigated mortality; we are continuing to follow these women for other health outcomes, and hope to examine outcomes such as quality of life, functional health and cognitive health, as well as the development of various diseases.
Disclosures: The study was funded by the National Institutes of Health. Dr. David Bassett is a member of the Scientific Advisory Board for Actigraph, which makes the device used to measure steps in the study. The study device was chosen prior to any involvement by Dr. Bassett. There are no other conflicts reported.
Lee I, Shiroma EJ, Kamada M, Bassett DR, Matthews CE, Buring JE. Association of Step Volume and Intensity With All-Cause Mortality in Older Women. JAMA Intern Med. Published online May 29, 2019. doi:10.1001/jamainternmed.2019.0899
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