Effect of age on the variability and stability of gait: a cross-sectional treadmill study in healthy individuals between 20 and 69 years of age

TL;DR

This study investigates how gait stability and variability change with age in healthy adults, finding that gait instability increases notably after age 40-50, serving as an early fall risk indicator.

Contribution

It provides evidence that gait instability begins to accelerate after age 40-50, highlighting its potential as an early marker for fall risk in aging populations.

Findings

Gait speed, walk ratio, and acceleration variability are not dependent on age.

Gait instability in the mediolateral direction increases quadratically with age.

Gait instability may serve as an early indicator of fall risk.

Abstract

Falls during walking are a major health issue in the elderly population. Older individuals are usually more cautious, work more slowly, take shorter steps, and exhibit increased step-to-step variability. They often have impaired dynamic balance, which explains their increased falling risk. Those locomotor characteristics might be the result of the neurological/musculoskeletal degenerative processes typical of advanced age or of a decline that began earlier in life. In order to help determine between the two possibilities, we analyzed the relationship between age and gait features among 100 individuals aged 20-69. Trunk acceleration was measured during 5-min treadmill session using a 3D accelerometer. The following dependent variables were assessed: preferred walking speed, walk ratio (step length normalized by step frequency), gait instability (local dynamic stability, Lyapunov exponent method), and acceleration variability (root mean square (RMS)). Using age as a predictor, linear regressions were performed for each dependent variable. The results indicated that walking speed, walk ratio and trunk acceleration variability were not dependent on age (R2<2%). However, there was a significant quadratic association between age and gait instability in the mediolateral direction (R2=15%). We concluded that most of the typical gait features of older age do not result from a slow evolution over the life course. On the other hand, gait instability likely begins to increase at an accelerated rate as early as age 40-50. This finding support the premise that local dynamic stability is likely a relevant early indicator of falling risk.