Six-minute walk test in healthy children: is the leg length important?

Measures as height, age, and weight influence the six-minute walk test (6MWT). It was shown that children's true leg length (TLL) influence the 6MWT distance but so far it has never been evaluated how much this variable could predict the distance walked related to height. Our hypothesis is that there should not have any significant difference between models including height or TLL.

To establish and to compare the predicted walked distance of healthy children in the 6MWT by two distinct models, one including TLL and other including height.

Observational cross sectional study. A total of 161 healthy children (84 girls, 52.2%), 6-13 years old from three local primary and secondary schools. Two 6MWT were performed following ATS guidelines. Weight, height, and TLL were measured. The longer walked distance was selected for statistical analysis.

Anthropometric data were similar for both genders into each group of age. Mean (±SD) walked distances in whole group were: boys 704.4 m (77.7); girls 681.6 m (67.9; P = 0.049). In the univariate regression to predict the distance walked, the adjusted coefficients to TLL and height were in boys: 0.46 and 0.39; and in girls: 0.35 and 0.29, respectively. After adjusting for age and weight, the residuals of the two equations were not significantly different (P = 0.998).

The model including TLL to predict the walked distance by healthy children explained more of the variation on the walked distance in the 6MWT than the model using the height but without significant difference between the models.