title: The influence of initial bipedal stance width on the clinical measurement of unipedal balance time.
abstract: OBJECTIVE
  To determine the effect of varying initial bipedal stance width (ISW) on the clinical measurement of unipedal balance time (UBT).
  
  
  METHODS
  Observational, cross-sectional study.
  
  
  METHODS
  Academic physiatric outpatient facility.
  
  
  METHODS
  Thirty-one clinic subjects with neuromuscular and/or musculoskeletal conditions known to influence mobility and 30 similarly-aged healthy subjects.
  
  
  METHODS
  Demographic and clinical information were recorded. UBT was determined under 3 distinct conditions by varying bipedal intermalleolar distance: (1) ISW of 0.3 body height; (2) ISW of 0.05 body height; and (3) ISW of 0 body height. The last was accomplished by subjects assuming unipedal balance while using the hands on a horizontal surface for stabilization. Subjects lifted the contralateral foot (or hands in the case of 0 body height condition) in response to a cadenced command to minimize variation in rate of weight transfer.
  
  
  METHODS
  UBT under each of the 3 ISW conditions.
  
  
  RESULTS
  Mean UBT increased with decreasing ISW, and the differences were significant when comparing each ISW with the next smaller. Healthy subjects demonstrated greater UBT than clinic subjects at each ISW, but the magnitude of these group differences were similar across ISW condition. A UBT >10 seconds in the 0.3 body height ISW was the best discriminator between clinic and healthy subjects.
  
  
  CONCLUSIONS
  Because UBT varies with ISW, standardization of ISW is necessary for accurate within-subject, and between-subject, comparisons in UBT. Healthy subjects were best differentiated from clinic subjects by UBT >10 seconds in the 0.3 body height ISW condition.
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Michigan Health Systems, Ann Arbor, MI 48103, USA. jkrich@umich.edu
authors.forename: James K
authors.initials: JK
authors.lastname: Richardson
authors.forename: Chi
authors.initials: C
authors.lastname: Tang
authors.forename: Chijioke
authors.initials: C
authors.lastname: Nwagwu
authors.forename: Joseph
authors.initials: J
authors.lastname: Nnodim
mesh_terms: D000328:Adult; D000368:Aged; D001827:Body Height; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009140:Musculoskeletal Diseases / Q000175:diagnosis* / Q000503:physiopathology* / Q000534:rehabilitation; D009468:Neuromuscular Diseases / Q000175:diagnosis* / Q000503:physiopathology* / Q000534:rehabilitation; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013997:Time Factors; D016474:Weight-Bearing / Q000502:physiology