title: 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.
abstract: 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.
authors.affiliation: IRR, Institute for Research in Rehabilitation, Sion, Switzerland; Clinique romande de réadaptation SUVACare, Sion, Switzerland. Electronic address: Philippe.Terrier@crr-suva.ch.
authors.forename: Philippe
authors.initials: P
authors.lastname: Terrier
authors.affiliation: Clinique romande de réadaptation SUVACare, Sion, Switzerland.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Reynard
mesh_terms: D000054:Acceleration; D061725:Accelerometry; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000886:Anthropometry; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D004856:Postural Balance / Q000502:physiology*; D012016:Reference Values; D060726:Torso / Q000502:physiology; D016138:Walking; D055815:Young Adult
keywords: Accelerometer; Aging; Dynamic balance; Fall risk; Local dynamic stability