title: Gait biomechanics, spatial and temporal characteristics, and the energy cost of walking in older adults with impaired mobility.
abstract: BACKGROUND
  Abnormalities of gait and changes in posture during walking are more common in older adults than in young adults and may contribute to an increase in the energy expended for walking.
  
  
  OBJECTIVE
  The objective of this study was to examine the contributions of abnormalities of gait biomechanics (hip extension, trunk flexion, and foot-floor angle at heel-strike) and gait characteristics (step width, stance time, and cadence) to the energy cost of walking in older adults with impaired mobility.
  
  
  METHODS
  A cross-sectional design was used.
  
  
  METHODS
  Gait speed, step width, stance time, and cadence were derived during walking on an instrumented walkway. Trunk flexion, hip extension, and foot-floor angle at heel contact were assessed during overground walking. The energy cost of walking was determined from oxygen consumption data collected during treadmill walking. All measurements were collected at the participants' usual, self-selected walking speed.
  
  
  RESULTS
  Fifty community-dwelling older adults with slow and variable gait participated. Hip extension, trunk flexion, and step width were factors related to the energy cost of walking. Hip extension, step width, and cadence were the only gait measures beyond age and gait speed that provided additional contributions to the variance of the energy cost, with mean R(2) changes of .22, .12, and .07, respectively. Limitations Other factors not investigated in this study (interactions among variables, psychosocial factors, muscle strength [force-generating capacity], range of motion, body composition, and resting metabolic rate) may further explain the greater energy cost of walking in older adults with slow and variable gait.
  
  
  CONCLUSIONS
  Closer inspection of hip extension, step width, and cadence during physical therapy gait assessments may assist physical therapists in recognizing factors that contribute to the greater energy cost of walking in older adults.
authors.affiliation: Department of Physical Therapy, University of Pittsburgh, 6035 Forbes Tower, Pittsburgh, PA 15260, USA. dmw29@pitt.edu
authors.forename: David M
authors.initials: DM
authors.lastname: Wert
authors.forename: Jennifer
authors.initials: J
authors.lastname: Brach
authors.forename: Subashan
authors.initials: S
authors.lastname: Perera
authors.forename: Jessie M
authors.initials: JM
authors.lastname: VanSwearingen
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D001696:Biomechanical Phenomena; D015897:Comorbidity; D003430:Cross-Sectional Studies; D004734:Energy Metabolism; D005260:Female; D005684:Gait / Q000502:physiology*; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D051346:Mobility Limitation; D010101:Oxygen Consumption / Q000502:physiology; D013997:Time Factors; D016138:Walking / Q000502:physiology*