Article

Falls during walking are a major health issue in the elderly population. Older
individuals are usually more cautious, walk 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 a 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
(R(2)<2%). However, there was a significant quadratic association between age and
gait instability in the mediolateral direction (R(2)=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 supports the
premise that local dynamic stability is likely a relevant early indicator of
falling risk.
CI - Copyright (c) 2014 Elsevier B.V. All rights reserved.

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