title: One step, two steps, three steps more ... Directional vulnerability to falls in community-dwelling older people.
abstract: BACKGROUND
  Falls leading to disability are common occurrences with advancing age. Stepping is a natural protective option for maintaining balance and preventing falls. There are directionally dependent challenges for protective stepping associated with falls among older individuals. The aim of this study was to determine the stepping response patterns evoked by different directions of externally applied postural disturbances in younger and older adults and in relation to falls.
  
  
  METHODS
  Seventy-five community-dwelling adults were tested: 26 younger adults and 49 older adults. Fall history of older participants was tracked prospectively for 1 year after testing. Steps were randomly evoked in 12 directions by a motorized waist-pull system. The number of recovery steps, type of stepping strategy, and first step kinematic characteristics were determined.
  
  
  RESULTS
  Younger participants mainly used single recovery steps regardless of the perturbation direction. For the older groups, multiple steps occurred predominantly and were least for the forward-backward directions and greatest for the lateral directions. Trials with three or more recovery steps were increased laterally only for the fallers. Overall, fallers initiated stepping earliest, but other stepping characteristics were similar between the groups for forward-backward perturbations. Aging differences in stepping strategies for diagonal and lateral perturbations included numerous interlimb collisions. Adaptive changes in stepping characteristics between forward and lateral perturbations were also observed in relation to age and risk of falls.
  
  
  CONCLUSIONS
  These results indicated an age-associated reduction in balance recovery effectiveness through stepping particularly for the lateral direction among older individuals at greater risk for falls.
authors.affiliation: PT, FAPTA, Department of Physical Therapy & Rehabilitation Science, School of Medicine, University of Maryland, 100 Penn Street, Allied Health Building 205D, Baltimore, MD 21201. mrogers@som.umaryland.edu.
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Mille
authors.forename: Marjorie
authors.initials: M
authors.lastname: Johnson-Hilliard
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Martinez
authors.forename: Yunhui
authors.initials: Y
authors.lastname: Zhang
authors.forename: Beatrice J
authors.initials: BJ
authors.lastname: Edwards
authors.forename: Mark W
authors.initials: MW
authors.lastname: Rogers
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena / Q000502:physiology; D003627:Data Interpretation, Statistical; D005260:Female; D015577:Geriatric Assessment / Q000379:methods; D006801:Humans; D057187:Independent Living; D008297:Male; D009048:Motor Skills / Q000502:physiology*; D004856:Postural Balance; D018570:Risk Assessment / Q000379:methods; D016138:Walking / Q000502:physiology*
keywords: Balance; Falls; Motor control.