title: Six-minute walk test: reference values and prediction equation in healthy boys aged 5 to 12 years.
abstract: OBJECTIVE
  This study aimed to (1) generate normative data in healthy boys aged 5-12 years for the six-minute walk test (6MWT), an outcome measure currently used in clinical trials in Duchenne muscular dystrophy (DMD), (2) to describe the relation with anthropometric variables and myometry, and (3) to compare our data with published equations.
  
  
  METHODS
  The 6MWT was conducted in 442 boys according to a standardized protocol, as currently used in clinical trials in DMD. Maximal voluntary isometric contractions for knee flexion and extension were recorded with a hand-held myometer.
  
  
  RESULTS
  The 6MWD increased significantly with age, from 478.0 ± 44.1 m at age 5, to 650.0 ± 76.8 m at age 12, with the steepest increase between 5 and 8 years. Age- and height related percentile curves of the 6MWD were developed. Correlations with anthropometric variables were fair to good (age r = 0.60, height r = 0.57, weight r = 0.44). Myometric variables (knee flexors and extensors) showed correlations of 0.46 and 0.50 respectively. When dividing into two age categories (5-8 years, 9-12 years), these magnitudes of correlations only applied to the younger age group. Additionally, predicted values were calculated according to available reference equations (Geiger and Ben Saad), indicating an overestimation by those equations. Finally, the Geiger equation was refitted to our population.
  
  
  CONCLUSIONS
  The percentile curves according to age and height provide a useful tool in the assessment of ambulatory capacity in boys aged 5 to 12 years. Significant correlations with anthropometric variables and myometry were only found in the 5-8 years age group. The Geiger prediction equation, currently used to assess ambulatory capacity in DMD was refitted to obtain a more accurate prediction model based on a large sample with a homogenous distribution across the age categories 5 to 12 years and applying the methodology as currently used in clinical trials in DMD.
authors.affiliation: Department of Child Neurology, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Goemans
authors.affiliation: Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Katrijn
authors.initials: K
authors.lastname: Klingels
authors.affiliation: Department of Child Neurology, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Marleen
authors.initials: M
authors.lastname: van den Hauwe
authors.affiliation: Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Boons
authors.affiliation: Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Liese
authors.initials: L
authors.lastname: Verstraete
authors.affiliation: Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Peeters
authors.affiliation: Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Hilde
authors.initials: H
authors.lastname: Feys
authors.affiliation: Department of Child Neurology, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Buyse
mesh_terms: D000367:Age Factors; D000886:Anthropometry; D002648:Child; D002675:Child, Preschool; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D006801:Humans; D008297:Male; D015233:Models, Statistical; D020388:Muscular Dystrophy, Duchenne / Q000175:diagnosis*; D017063:Outcome Assessment, Health Care; D011237:Predictive Value of Tests; D012016:Reference Values; D016138:Walking / Q000502:physiology*