The six-minute walk test in obese youth: reproducibility, validity, and prediction equation to assess aerobic power

Purpose: The aim of this study was to assess reproducibility and validity of the 6 minute walk test (6MWT) in obese youth and to develop an equation to predict aerobic power (VO2max). Methods: Fifty-two girls and 45 boys, ages 7-17.8 participated in the study. Three walk tests were administered 1 week apart. Each visit corresponded to a specific test, either an incremental treadmill test, or the 6MWT. The 6MWT was performed on two occasions 1 week apart to assess reproducibility. Treadmill and walk tests were randomly assigned to avoid order effect. Results: Subjects walked 689.4 +/- 98.6 m on the initial 6MWT and 690.4 +/- 98.2 m on the second test. Intraclass correlation coefficient was r = 0.99. The Bland and Altman method also showed good agreement between the two 6MWTs. Stepwise multiple regression determined that distance walked in 6 MWT and BMI are the most significant factors in predicting VO2max. The prediction equation is VO2max (ml.kg.min(-1)) = 26.9 + 0.014 x 6 MWT (meters) -0.38 x BMI (kg/m(2)). Conclusions: In obese youth, the 6 MWT is a reproducible and valid test for assessing aerobic power. A prediction equation was developed to estimate VO2max, using distance walked in 6MWT and BMI.