title: Reference equations for the six-minute walk distance based on a Brazilian multicenter study.
abstract: BACKGROUND
  It is important to include large sample sizes and different factors that influence the six-minute walking distance (6MWD) in order to propose reference equations for the six-minute walking test (6 MWT).
  
  
  OBJECTIVE
  To evaluate the influence of anthropometric, demographic, and physiologic variables on the 6 MWD of healthy subjects from different regions of Brazil to establish a reference equation for the Brazilian population.
  
  
  METHODS
  In a multicenter study, 617 healthy subjects performed two 6 MWTs and had their weight, height, and body mass index (BMI) measured, as well as their physiologic responses to the test. Delta heart rate (∆HR), perceived effort, and peripheral oxygen saturation were calculated by the difference between the respective values at the end of the test minus the baseline value.
  
  
  RESULTS
  Walking distance averaged 586 ± 106 m, 54 m greater in male compared to female subjects (p<0.001). No differences were observed among the 6 MWD from different regions. The quadratic regression analysis considering only anthropometric and demographic data explained 46% of the variability in the 6 MWT (p<0.001) and derived the equation: 6 MWD(pred)=890.46-(6.11 × age)+(0.0345 × age(2))+(48.87 × gender)-(4.87 × BMI). A second model of stepwise multiple regression including ∆HR explained 62% of the variability (p<0.0001) and derived the equation: 6 MWD(pred)=356.658-(2.303 × age)+(36.648 × gender)+(1.704 × height)+(1.365×∆HR).
  
  
  CONCLUSIONS
  The equations proposed in this study, especially the second one, seem adequate to accurately predict the 6 MWD for Brazilians.
authors.affiliation: Universidade Federal de Minas Gerais, Physical Therapy Department, Belo HorizonteMG, Brazil.
authors.forename: Raquel R
authors.initials: RR
authors.lastname: Britto
authors.affiliation: Universidade Estadual de Londrina, Physical Therapy Department, LondrinaPR, Brazil.
authors.forename: Vanessa S
authors.initials: VS
authors.lastname: Probst
authors.affiliation: Universidade Federal de Minas Gerais, Physical Therapy Department, Belo HorizonteMG, Brazil.
authors.forename: Armele F Dornelas
authors.initials: AF
authors.lastname: de Andrade
authors.affiliation: Universidade Federal de Minas Gerais, Physical Therapy Department, Belo HorizonteMG, Brazil.
authors.forename: Giane A R
authors.initials: GA
authors.lastname: Samora
authors.affiliation: Universidade Estadual de Londrina, Physical Therapy Department, LondrinaPR, Brazil.
authors.forename: Nidia A
authors.initials: NA
authors.lastname: Hernandes
authors.affiliation: Universidade Federal de Pernambuco, Physical Therapy Department, RecifePE, Brazil.
authors.forename: Patrícia E M
authors.initials: PE
authors.lastname: Marinho
authors.affiliation: Universidade Federal de Ciências da Saúde de Porto Alegre, Porto AlegreRS, Brazil.
authors.forename: Marlus
authors.initials: M
authors.lastname: Karsten
authors.affiliation: Universidade Estadual de Londrina, Physical Therapy Department, LondrinaPR, Brazil.
authors.forename: Fabio
authors.initials: F
authors.lastname: Pitta
authors.affiliation: Universidade Federal de Minas Gerais, Physical Therapy Department, Belo HorizonteMG, Brazil.
authors.forename: Veronica F
authors.initials: VF
authors.lastname: Parreira
mesh_terms: D000328:Adult; D000368:Aged; D001938:Brazil; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013997:Time Factors; D016138:Walking; D055815:Young Adult