Predictive validity analysis of six reference equations for the 6-minute walk test in healthy Brazilian men: a cross-sectional study

BACKGROUND: The six-minute walk test (6MWT) is an important tool for evaluating functional capacity and exercise tolerance. The reference equations for the 6MWT in healthy subjects were established on the basis of American and European populations, but reference equations have been proposed with different variables for the Brazilian population. OBJECTIVE: To analyze the predictive validity of six reference equations for the six-minute walking distance (6MWD) in healthy adult men. METHODS: We evaluated 103 individuals in relation to level of physical activity (IPAQ), respiratory symptoms (MRC), handgrip strength, and 6MWD test. The data were submitted to a normality test, then the Bland–Altman agreement test was used to compare individual 6MWD values with that expected for each equation. RESULTS: The subjects were active, with a mean age of 34.12 (SD = 8.88) years and no respiratory symptoms. The mean of the 6MWD was 663.43 (SD = 93.01) m. The 6MWD's predicted values came closest to the walked distance covered by Britto et al.’s equation (using BMI) of 647.62 (SD = 38.62) m. CONCLUSIONS: The equation proposed by Britto et al. using body mass index (BMI) was the closest to the 6MWD for the individuals studied and could be widely used as a reference tool during the 6MWT in healthy Brazilian men.