title: Energy cost of walking and gait instability in healthy 65- and 80-yr-olds.
abstract: This study tested whether the lower economy of walking in healthy elderly subjects is due to greater gait instability. We compared the energy cost of walking and gait instability (assessed by stride to stride changes in the stride time) in octogenarians (G80, n = 10), 65-yr-olds (G65, n = 10), and young controls (G25, n = 10) walking on a treadmill at six different speeds. The energy cost of walking was higher for G80 than for G25 across the different walking speeds (P < 0.05). Stride time variability at preferred walking speed was significantly greater in G80 (2.31 +/- 0.68%) and G65 (1.93 +/- 0.39%) compared with G25 (1.40 +/- 0.30%; P < 0.05). There was no significant correlation between gait instability and energy cost of walking at preferred walking speed. These findings demonstrated greater energy expenditure in healthy elderly subjects while walking and increased gait instability. However, no relationship was noted between these two variables. The increase in energy cost is probably multifactorial, and our results suggest that gait instability is probably not the main contributing factor in this population. We thus concluded that other mechanisms, such as the energy expenditure associated with walking movements and related to mechanical work, or neuromuscular factors, are more likely involved in the higher cost of walking in elderly people.
authors.affiliation: Unite Propre de Recherche de l'Enseignement Superier (UPRES) 701, Hôpital Arnaud de Villeneuve, Montpellier, France.
authors.forename: Davide
authors.initials: D
authors.lastname: Malatesta
authors.forename: David
authors.initials: D
authors.lastname: Simar
authors.forename: Yves
authors.initials: Y
authors.lastname: Dauvilliers
authors.forename: Robin
authors.initials: R
authors.lastname: Candau
authors.forename: Fabio
authors.initials: F
authors.lastname: Borrani
authors.forename: Christian
authors.initials: C
authors.lastname: Prefaut
authors.forename: Corinne
authors.initials: C
authors.lastname: Caillaud
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001481:Basal Metabolism / Q000502:physiology; D001823:Body Composition / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000033:anatomy & histology / Q000502:physiology; D008875:Middle Aged; D008954:Models, Biological; D009043:Motor Activity / Q000502:physiology; D018482:Muscle, Skeletal / Q000254:growth & development / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D004856:Postural Balance / Q000502:physiology; D016138:Walking / Q000502:physiology*