Physical Activity Patterns and Incident Frailty in the National Health and Aging Trends Study

TL;DR

This study explores how patterns of physical activity measured by wearable devices relate to the development of frailty in older adults.

Contribution

The study introduces objective measures of physical activity patterns as potential predictors of frailty onset.

Findings

Higher active time and total activity counts were associated with lower odds of incident frailty.

Increased fragmentation and variability in physical activity patterns were linked to higher odds of frailty.

Accelerometer-derived physical activity metrics may serve as new markers for predicting frailty.

Abstract

Frailty is characterized in part by slow walking speed and low self-reported physical activity (PA), but there is limited evidence linking objective amount, intensity, and patterns of daily PA to frailty incidence. A deeper understanding of the characteristics of PA most strongly associated with frailty may help illuminate new markers for prevention. We examined the association between wrist-worn accelerometry-derived patterns of daily PA and incident frailty in the National Health and Aging Trends Study (NHATS). Frailty was defined as having ≥3 criteria of self-reported exhaustion, unintentional weight loss, low self-reported physical activity, and low measured grip strength and slow walking speed; having 1-2 criteria was considered prefrail. Daily PA features included total daily activity volume (total counts, active minutes/day), intensity (most active 5-minutes (M5) counts/day), fragmentation(%), and variability (intra-daily variability(IV), inter-daily stability(IS)). Survey-weighted multivariable logistic regression models were used to study the association between each accelerometer feature and incident frailty 1-year later, adjusting for sociodemographics and clinical conditions. In 519 participants with ≥3 days of valid accelerometry data who were robust or prefrail at baseline (33.5% aged ≥80 years, 56% female), 13.6% became frail. Every 30/min higher baseline active time, 100,000 more activity counts/day, and 1000 more M5 counts/day were associated with 13%[95% CI: 4%-21%], 8%[1%-15%], and 35%[21%-46%] lower odds of incident frailty, respectively. Additionally, every 1% higher fragmentation and 0.1 higher IV were associated with 7%[4%-11%] and 18%[6%-33%] higher odds of frailty. Future studies should investigate using accelerometer measures of PA to predict frailty onset.