title: Accuracy of the actibelt(®) accelerometer for measuring walking speed in a controlled environment among persons with multiple sclerosis.
abstract: BACKGROUND
  Advances in portable sensor technology have opened an era for objective, real-life monitoring of walking speed in persons with multiple sclerosis (MS).
  
  
  OBJECTIVE
  The present study examined the accuracy of the actibelt(®) accelerometer for measuring walking speed during a standard 6-min walk (6MW) and the possibility that disability status influenced the degree of accuracy among persons with MS.
  
  
  METHODS
  On a single testing session, 51 persons with MS and Expanded Disability Status Scale scores between 2.0 and 6.5 performed a 6MW while wearing an actibelt(®) in the body's sagittal symmetry plane and close to the body's centre of mass.
  
  
  RESULTS
  All 51 participants completed the 6MW without stopping, falling, or any adverse events, and the actibelt(®) provided walking speed data for each of the participants. The actibelt(®) significantly overestimated walking speed (actual minus actibelt(®)) by a mean±standard deviation of -0.12±0.17 m/s for the overall sample (p<0.0001). There was no significant overestimation in the sample with mild disability (-0.02±0.11 m/s), but there was in the samples with moderate (-0.10±0.16 m/s) and severe (-0.26±0.12 m/s) disability.
  
  
  CONCLUSIONS
  The actibelt(®) is ready for real-life monitoring of walking speed in persons with mild MS, but caution is necessary when interpreting the accuracy of the walking speed data for those with MS who have moderate and severe disability.
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois at Urbana Champaign, 350 Freer Hall, Urbana, IL 61801, USA. robmotl@illinois.edu
authors.forename: Robert W
authors.initials: RW
authors.lastname: Motl
authors.forename: Madeline
authors.initials: M
authors.lastname: Weikert
authors.forename: Yoojin
authors.initials: Y
authors.lastname: Suh
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: Sosnoff
authors.forename: John
authors.initials: J
authors.lastname: Pula
authors.forename: Cristina
authors.initials: C
authors.lastname: Soaz
authors.forename: Michaela
authors.initials: M
authors.lastname: Schimpl
authors.forename: Christian
authors.initials: C
authors.lastname: Lederer
authors.forename: Martin
authors.initials: M
authors.lastname: Daumer
mesh_terms: D000054:Acceleration; D000328:Adult; D000704:Analysis of Variance; D016001:Confidence Intervals; D004185:Disability Evaluation; D004734:Energy Metabolism; D005080:Exercise Test / Q000295:instrumentation*; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000503:physiopathology; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000503:physiopathology*; D018763:Muscle Fatigue / Q000502:physiology*; D011379:Prognosis; D012494:Sampling Studies; D012720:Severity of Illness Index; D013647:Task Performance and Analysis; D016138:Walking / Q000502:physiology*