title: Three-Month Test-Retest Reliability of Center of Pressure Motion During Standing Balance in Individuals with Multiple Sclerosis.
abstract: BACKGROUND
  Balance impairment and an increased rate of falls are commonly reported in individuals with multiple sclerosis (MS). Force platform-generated center of pressure (COP) metrics have previously been recommended as an outcome measure to quantify balance deficits and distinguish between fallers and nonfallers in MS. Information is limited regarding the preservation of postural control in individuals with MS over extended time frames in the absence of an intervention. This report examines the test-retest reliability and magnitude of change of COP motion during standing balance over 3 months.
  
  
  METHODS
  Twenty individuals with MS and a history of falling underwent testing on two occasions 3 months apart in the absence of an intervention. On both occasions, participants completed two 30-second trials of three conditions: eyes open, eyes closed, and eyes open with concurrent cognitive challenge (dual task). Measures of COP area, velocity, and temporal structure were calculated and included in the reliability analysis.
  
  
  RESULTS
  The COP metrics displayed fair-to-excellent reliability over 3 months without an intervention. Reliability was maintained across the three commonly used balance conditions.
  
  
  CONCLUSIONS
  These results offer insight into the reliability of COP measures over a 3-month period in MS and can inform the use of COP metrics for future study design (eg, sample size estimates) and balance outcome assessment during randomized controlled trials and fall-prevention studies in individuals with MS.
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Wajda
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Motl
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: Sosnoff