other·PMC10184809

Dose–Response Relationships between Objectively Measured Daily Steps and Mortality among Frail and Nonfrail Older Adults

Medicine and Science in Sports and Exercise · 6 authors, 7 centres

AI SUMMARY

FIDELITY 100%

POPULATION4165 community-dwelling older adults aged 65 years or older from the Kyoto–Kameoka study in Japan

INTERVENTIONObjectively measured daily step counts (quartiles: mean 1786, 3030, 4452, 7502 steps/day)

COMPARISONLowest quartile of daily step count (mean 1786 steps/day) vs. higher quartiles; stratified by frailty status (frail vs. nonfrail)

This summary was generated by AI from a single paper. It has not been reviewed by a clinician and is not clinical advice. Verify against the source before acting on it.

AGENT 01 · STRUCTURED SUMMARY

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TL;DR

This prospective cohort study of 4165 Japanese older adults found that higher daily step counts were associated with lower all-cause mortality, but the dose-response relationship differed by frailty status. For nonfrail individuals, mortality risk plateaued at approximately 5000–7000 steps per day, whereas frail individuals required 5000 or more steps per day to achieve an inverse association with mortality. These findings suggest that physical activity guidelines may need to consider frailty status when setting step count targets for older adults.

Full summary

3,350 CHARS

**Background:** Frailty affects 12%–24% of adults over 50 and is strongly associated with mortality. While daily step count is a simple, objective measure of physical activity inversely associated with mortality, it was unclear whether this association differs between frail and nonfrail older adults. This study aimed to evaluate the dose-dependent relationship between step count and all-cause mortality in community-dwelling older adults with and without frailty.

**Methods:** This prospective study used data from 4165 participants aged 65 years or older from the Kyoto–Kameoka study in Japan. Participants wore a triaxial accelerometer (EW-NK52; Panasonic) for at least 4 days, and daily step counts were averaged and classified into quartiles (Q1: mean 1786 steps; Q2: 3030; Q3: 4452; Q4: 7502). Frailty was assessed using the validated 25-item Kihon Checklist, with frailty defined as ≥7 positive items (prevalence 24.7%). All-cause mortality was ascertained from the Basic Resident Register through November 30, 2016 (median follow-up 3.38 years). Multivariable Cox proportional hazards models adjusted for age, sex, population density, season, body mass index, smoking, alcohol, living alone, education, socioeconomic status, denture use, medication use, number of chronic diseases, and frailty. Restricted cubic spline models with three knots evaluated dose-response relationships.

**Key Results:** During 14,061 person-years, 113 deaths (2.7%) occurred. Compared with Q1, adjusted hazard ratios (HR) for mortality were: Q2 HR=0.84 (95% CI 0.53–1.32), Q3 HR=0.57 (95% CI 0.31–1.03), Q4 HR=0.39 (95% CI 0.18–0.85) (P for trend=0.003). Per 1000-step increase, HR was 0.81 (95% CI 0.68–0.94) overall, 0.77 (95% CI 0.56–0.98) for <5000 steps/day, and 1.04 (95% CI 0.68–1.40) for ≥5000 steps/day. In the spline model, mortality risk plateaued at approximately 5000–7000 steps/day overall (P for nonlinearity=0.019). Stratified by frailty: among nonfrail individuals (n=3136), HR per 1000 steps was 0.86 (95% CI 0.71–1.00), with plateau at 5000–7000 steps/day (P for nonlinearity=0.012). Among frail individuals (n=1029), HR per 1000 steps was 0.65 (95% CI 0.39–0.92), with an inverse relationship at ≥5000 steps/day (P for nonlinearity=0.021). For frail individuals with ≥2500 steps/day, HR per 1000 steps was 0.28 (95% CI 0.07–0.97). The difference between frailty groups was significant (P for between groups=0.048).

**Clinical Implications:** This study provides the first evidence that the dose-response relationship between objectively measured daily steps and mortality differs by frailty status in older adults. Nonfrail individuals achieve maximal mortality benefit at 5000–7000 steps/day, while frail individuals may require ≥5000 steps/day to see an inverse association. These findings suggest that a single step-count target (e.g., 10,000 steps/day) may be inappropriate for all older adults. A modest increase of approximately 1000 steps/day (a "+10" minute approach) could be an achievable goal for many sedentary older adults. Limitations include potential selection bias (participants were healthier than the general population), short follow-up (3.38 years), single baseline step measurement, and inability to assess cause-specific mortality. Further studies with longer follow-up and randomly sampled participants are needed.

PICO

PPOPULATION

4165 community-dwelling older adults aged 65 years or older from the Kyoto–Kameoka study in Japan

IINTERVENTION

Objectively measured daily step counts (quartiles: mean 1786, 3030, 4452, 7502 steps/day)

OOUTCOME

All-cause mortality during median follow-up of 3.38 years (14,061 person-years; 113 deaths)

STUDY TYPE

other

SPECIALTY

Not tagged

SUMMARISED BY

AI pipeline

FIDELITY CHECK

100% · A

ORIGINAL PAPER

PMC10184809

Dose–Response Relationships between Objectively Measured Daily Steps and Mortality among Frail and Nonfrail Older Adults

Medicine and Science in Sports and Exercise

READ THE FULL PAPER

ABSTRACT

ABSTRACT Purpose Whether the association between objectively assessed physical activity and mortality differs between adults with versus those without frailty is unclear. We investigated this association in community-dwelling older adults. Methods This prospective study used the data of 4165 older adults 65 yr or older from the Kyoto–Kameoka study in Japan who wore a triaxial accelerometer (EW-NK52). The number of steps was classified by quartiles using the average daily value of data obtained from the accelerometer across four or more days. Frailty was evaluated using the validated Kihon Checklist. We evaluated the association between mortality and daily steps using a multivariable Cox proportional hazards analysis and restricted spline model. Results The average daily steps for the first, second, third, and fourth quartiles were 1786, 3030, 4452, and 7502, respectively. In total, 113 deaths were recorded during a median follow-up of 3.38 yr (14,061 person-years). After adjusting for confounders, the top quartile was associated with a lower hazard ratio (HR) for mortality than the bottom quartile (HR = 0.39, 95% confidence interval = 0.18–0.85). In a stratified model by frailty status, the daily step count dose–response curve at which the HR for mortality plateaued among nonfrail individuals was approximately 5000–7000 steps per day. By contrast, the daily step count showed an inverse relationship with mortality at approximately 5000 steps or more per day in frail individuals. Conclusions The relationship between daily steps and mortality is different between those with and those without frailty, and people with frailty may require more daily steps than those with nonfrailty to achieve the inverse relationship with mortality. These findings may be useful for informing future physical activity guidelines.

CITATION EXPORT

DAIKI WATANABE, TSUKASA YOSHIDA, YUYA WATANABE et al.. Dose–Response Relationships between Objectively Measured Daily Steps and Mortality among Frail and Nonfrail Older Adults. Medicine and Science in Sports and Exercise. (2023). https://doi.org/10.1249/MSS.0000000000003133

AUTHORS

6 · 7 CENTRES

DAIKI WATANABE, TSUKASA YOSHIDA, YUYA WATANABE, YOSUKE YAMADA, MOTOHIKO MIYACHI, MISAKA KIMURA

1Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama, JAPAN
2National Institute of Health and Nutrition, National Institutes of Biomedical Innovation, Health and Nutrition, Shinjuku-ku, Tokyo, JAPAN
3Institute for Active Health, Kyoto University of Advanced Science, Kameoka, Kyoto, JAPAN
4Senior Citizen’s Welfare Section, Kameoka City Government, Kameoka, Kyoto, JAPAN
5Physical Fitness Research Institute, Meiji Yasuda Life Foundation of Health and Welfare, Hachioji, Tokyo, JAPAN
6Department of Nursing, Doshisha Women’s College of Liberal Arts, Kyotanabe, Kyoto, JAPAN
7Laboratory of Applied Health Sciences, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto, JAPAN