Criterion-related validity and reliability of the 6-minute walk test in adults according to sex, age and physical activity level: The ADULT-FIT project

This study aimed to analyse the criterion-related validity and reliability of the 6-minute walk test (6MWT) to assess cardiorespiratory fitness in the adult population, according to sex, age and physical activity level. Sociodemographic and anthropometric measurements, a treadmill maximal test, and the 6MWT were performed on 410 adults aged 18-64 years. Measured VO2max was associated with the total distance in the 6MWT and estimated VO2max by Burr's and Manttari's equations (R2 = 0.35, 0.61 and 0.61, respectively, all p < 0.01; SEE = 6.564-5.089 ml* kg-1 * min-1, %SEE = 11.80-15.30). The stepwise linear regression analysis showed that the total distance in the 6MWT, sex, age, physical activity level and body fat mass (%) explained 75% variance of measured VO2max (SEE = 4.203 ml* kg-1 * min-1, %SEE = 9.78, p < 0.001). The systematic error in the total distance in the 6MWT was 0.87-m (p < 0.001). The ICC showed excellent agreement (0.99, p < 0.001), with low error values and most of the MCD95 close to 0.