Reference equations for the six-minute walk distance based on a Brazilian multicenter study

Braz J Phys Ther. Nov-Dec 2013;17(6):556-63. doi: 10.1590/S1413-35552012005000122. Epub 2013 Nov 14.

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.

Method: 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).

Conclusion: The equations proposed in this study, especially the second one, seem adequate to accurately predict the 6 MWD for Brazilians.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Brazil
  • Exercise Test / methods*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Reference Values
  • Time Factors
  • Walking*
  • Young Adult

Grant support

The authors would like to thank the undergraduate students who helped with data collection and Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq, Brazil (process 77137/2008-3) and Fundação de Amparo a Pesquisa do Estado de Minas Gerais-FAPEMIG, Brazil (PPM00072-09) for their financial support.