Objective Measures of Physical Activity and Frailty in Ambulatory Adults Aged 85–89 Years in Kawasaki, Japan: A Cross-sectional Study

Background

While physical activity (PA) can reduce physical frailty, the specific intensity and duration of PA required to prevent frailty are yet to be defined.

Objectives

This study aimed to investigate the relationship between objectively measured PA or sedentary behavior (SB) and physical frailty and to explore the theoretical effect of replacing SB with different intensities of PA on the risk of frailty.

Design

Cross-sectional study.

Setting

Community-based assessments.

Participants

Independently living adults aged 85–89 years participating in the Kawasaki Aging and Wellbeing Project.

Measurements

PA was measured using a triaxial accelerometer for a minimum of 10 h per day over a minimum of 3 days. Physical frailty was measured using the revised Japanese version of the Cardiovascular Health Study criteria. Physical frailty was classified as non-frail, pre-frail, and frail. The relationship between PA and frailty was assessed using analysis of covariance. The effect of replacing SB with light-intensity PA (LPA) or moderate-to-vigorous-intensity PA (MVPA) on the risk of frailty was estimated using multinomial logistic regression and an isotemporal substitution model.

Results

The analysis included 1004 participants (503 men and 501 women) of whom 242 were classified as frail. The mean step count, MVPA, and LPA were lower, and SB was higher in the frail group than in the non-frail group. SB replacement with MVPA for 10 min/day was associated with a significantly lower odds of frailty (odds ratio [95% confidence interval]: pre-frail men, 0.86 [0.77, 0.96]; frail men, 0.70 [0.60, 0.83]; pre-frail women, 0.77 [0.66, 0.90], frail women, 0.59 [0.47, 0.75]). SB replacement with LPA was not significantly associated with frailty odds in men or women.

Conclusions

Replacing 10 min of SB with MVPA was associated with lower risk of frailty in adults aged 85–89 years. These findings require confirmation in longitudinal and intervention studies.