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Original Investigation
May 29, 2019

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

Author Affiliations
  • 1Division of Preventive Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
  • 2Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
  • 3Laboratory of Epidemiology and Population Science, National Institute on Aging, Baltimore, Maryland
  • 4Department of Health and Social Behavior, School of Public Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
  • 5Department of Kinesiology, Recreation, and Sport Studies, University of Tennessee, Knoxville
  • 6Metabolic Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland
JAMA Intern Med. 2019;179(8):1105-1112. doi:10.1001/jamainternmed.2019.0899
Key Points

Question  Are increased numbers of steps per day associated with lower mortality rates among older women?

Findings  In this cohort study of 16 741 women with a mean age of 72 years, steps per day were measured over 7 days. Women who averaged approximately 4400 steps/d had significantly lower mortality rates during a follow-up of 4.3 years compared with the least active women who took approximately 2700 steps/d; as more steps per day were accrued, mortality rates progressively decreased before leveling at approximately 7500 steps/d.

Meaning  More steps taken per day are associated with lower mortality rates until approximately 7500 steps/d.

Abstract

Importance  A goal of 10 000 steps/d is commonly believed by the public to be necessary for health, but this number has limited scientific basis. Additionally, it is unknown whether greater stepping intensity is associated with health benefits, independent of steps taken per day.

Objective  To examine associations of number of steps per day and stepping intensity with all-cause mortality.

Design, Setting, and Participants  This prospective cohort study included 18 289 US women from the Women’s Health Study who agreed to participate by wearing an accelerometer during waking hours for 7 days between 2011 and 2015. A total of 17 708 women wore and returned their devices; data were downloaded successfully from 17 466 devices. Of these women, 16 741 were compliant wearers (≥10 h/d of wear on ≥4 days) and included in the analyses, which took place between 2018 and 2019.

Exposures  Steps per day and several measures of stepping intensity (ie, peak 1-minute cadence; peak 30-minute cadence; maximum 5-minute cadence; time spent at a stepping rate of ≥40 steps/min, reflecting purposeful steps).

Main Outcomes and Measures  All-cause mortality.

Results  Of the 16 741 women who met inclusion criteria, the mean (SD) age was 72.0 (5.7) years. Mean step count was 5499 per day, with 51.4%, 45.5%, and 3.1% of time spent at 0, 1 to 39 (incidental steps), and 40 steps/min or greater (purposeful steps), respectively. During a mean follow-up of 4.3 years, 504 women died. Median steps per day across low-to-high quartiles of distribution were 2718, 4363, 5905, and 8442, respectively. The corresponding quartile hazard ratios (HRs) associated with mortality and adjusted for potential confounders were 1.00 (reference), 0.59 (95% CI, 0.47-0.75), 0.54 (95% CI, 0.41-0.72), and 0.42 (95% CI, 0.30-0.60), respectively (P < .01). In spline analysis, HRs were observed to decline progressively with higher mean steps per day until approximately 7500 steps/d, after which they leveled. For measures of stepping intensity, higher intensities were associated with significantly lower mortality rates; however, after adjusting for steps per day, all associations were attenuated, and most were no longer significant (highest vs lowest quartile for peak 1-minute cadence, HR = 0.87 [95% CI, 0.68-1.11]; peak 30-minute cadence, HR = 0.86 [95% CI, 0.65-1.13]; maximum 5-minute cadence, HR = 0.80 [95% CI, 0.62-1.05]; and time spent at a stepping rate of ≥40 steps/min, HR = 1.27 [95% CI, 0.96-1.68]; P > .05).

Conclusions and Relevance  Among older women, as few as approximately 4400 steps/d was significantly related to lower mortality rates compared with approximately 2700 steps/d. With more steps per day, mortality rates progressively decreased before leveling at approximately 7500 steps/d. Stepping intensity was not clearly related to lower mortality rates after accounting for total steps per day.

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    3 Comments for this article
    EXPAND ALL
    Really?
    Harry Vu |
    It's hard to fathom how a person's step activity for 7 days could have any influence on their demise 4 years later. Seriously.
    CONFLICT OF INTEREST: None Reported
    Very useful for people taking care of our senior citizens
    Esteban Perez-Wohlfeil, PhD Student | University Of Malaga
    I enjoyed the read.

    Best regards,
    Esteban
    CONFLICT OF INTEREST: None Reported
    Limit of the association of step volume and intensity in mortality rates
    DANIEL LOPEZ-HERNANDEZ, Ph.D M.Sc Physician M.D | Institute of Security and Social Services of State Workers
    The results of the study by Lee et al provide epidemiological evidence of the benefit of walking on all-cause mortality, however, it also generates uncertainties about the analysis of life course and what are the social determinants of health that favored such protection between the different subgroups?

    It is noteworthy that the prevalence of chronic diseases decreases among the different groups of quartiles, this suggests that the lifestyles are different between each group of analysis, therefore, the logical question would be if all the age groups are represented in each quartile.

    In addition, the study provides evidence that
    suggests the implementation of a public health program for active and healthy aging and the later analysis of the results on the prevalence of mortality in this population group.
    CONFLICT OF INTEREST: None Reported
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