Reference Equations for the Six-Minute Walk Distance in the Healthy Chinese Han Population, Aged 18-30 Years

The six-minute walk test (6MWT) is a safe, simple, inexpensive tool for evaluating the functional exercise capacity. However, there is a lack of standard reference equations for the six-minute walk distance (6MWD) in the healthy Chinese Han population with an age of 18-30 years. The aims of the present study were as follows: 1) to measure the anthropometric data and the walking distance in a sample of healthy Chinese Han population, aged 18-30 years; 2) to construct reference equations for the 6MWD; 3) to compare the measured 6MWD of our cohort with previously published equations.

The anthropometric data, demographic, lung function and the walking distance of Chinese Han population, aged 18-30 years, were prospectively measured using a standardized protocol. Informed consent was obtained from each participant and the approval was obtained from the ethics committee of Wenzhou People's Hospital. The 6MWT was performed twice and the longer 6MWD was used for further analysis.

A total of 355 subjects (176 female and 179 male) completed the 6MWT, and the average walking distance was 627.3 ± 52.88 m. The walking distance was achieved by females compared with males (607.4 ± 51.00 m vs. 646.9 ± 47.15 m; p < 0.0001) and active subjects compared with non-active subjects (646.1 ± 48.27 m vs. 611.6 ± 51.52 m; p < 0.0001). Univariate analysis showed age, height, body mass index, resting blood pressure, heart rate and blood pressure after the walk test and difference in heart rate before and after the walk test were significantly correlated with the 6MWD. Stepwise multiple regression analysis showed that height and difference in heart rate before and after the walk test were independent predictors associated with the 6MWD. The reference equations from Caucasian, Canadian and Chilean populations tend to overestimate the walking distance in our subjects, while Brazilian and Arabian equations tend to underestimate the walking distance. There was no significant difference in the walking distance between Korean equations and the current study.

In summary, height and difference in heart rate before and after the walk test were the most significant predictors of the 6MWD, and the regression equations could explain approximately 38% and 31% of the distance variance in the female and male groups, respectively.