title: Aging and partial body weight support affects gait variability.
abstract: BACKGROUND
  Aging leads to increases in gait variability which may explain the large incidence of falls in the elderly. Body weight support training may be utilized to improve gait in the elderly and minimize falls. However, before initiating rehabilitation protocols, baseline studies are needed to identify the effect of body weight support on elderly gait variability. Our purpose was to determine the kinematic variability of the lower extremities in young and elderly healthy females at changing levels of body weight support during walking.
  
  
  METHODS
  Ten young and ten elderly females walked on a treadmill for two minutes with a body weight support (BWS) system under four different conditions: 1 g, 0.9 g, 0.8 g, and 0.7 g. Three-dimensional kinematics was captured at 60 Hz with a Peak Performance high speed video system. Magnitude and structure of variability of the sagittal plane angular kinematics of the right lower extremity was analyzed using both linear (magnitude; standard deviations and coefficient of variations) and nonlinear (structure; Lyapunov exponents) measures. A two way mixed ANOVA was used to evaluate the effect of age and BWS on variability.
  
  
  RESULTS
  Linear analysis showed that the elderly presented significantly more variability at the hip and knee joint than the young females. Moreover, higher levels of BWS presented increased variability at all joints as found in both the linear and nonlinear measures utilized.
  
  
  CONCLUSIONS
  Increased levels of BWS increased lower extremity kinematic variability. If the intent of BWS training is to decrease variability in gait patterns, this did not occur based on our results. However, we did not perform a training study. Thus, it is possible that after several weeks of training and increased habituation, these initial increased variability values will decrease. This assumption needs to be addressed in future investigation with both "healthy" elderly and elderly fallers. In addition, it is possible that BWS training can have a positive transfer effect by bringing overground kinematic variability to healthy normative levels, which also needs to be explored in future studies.
authors.affiliation: HPER Biomechanics Lab, University of Nebraska at Omaha, NE 68182-0216, USA. akyvelidou@mail.unomaha.edu
authors.forename: Anastasia
authors.initials: A
authors.lastname: Kyvelidou
authors.forename: Max J
authors.initials: MJ
authors.lastname: Kurz
authors.forename: Julie L
authors.initials: JL
authors.lastname: Ehlers
authors.forename: Nicholas
authors.initials: N
authors.lastname: Stergiou
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology*; D001835:Body Weight / Q000502:physiology*; D005260:Female; D005684:Gait / Q000502:physiology*; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult