A performance comparison of the 20 and 30 meter six-minute walk tests among middle aged and older adults.

Objective: To compare the performance of the Six-Minute Walk Test on 20-meter (6MWT20) and 30-meter (6MWT30) tracks and to test the validity and reliability of the 6MWT20 in middle-aged and older adults.Method: The subjects underwent lung function assessment and performed the 6MWT30 and 6MWT20. Student´s t-tests or Wilcoxon tests were used to compare the variables. The Pearson or Spearman correlation coefficients were used to evaluate the validity of the 6MWT20 and the reliability of the 6MWT20. The 6MWT30 was tested by the two-way mixed model of the Intraclass Correlation Coefficient (ICC 3,1).Results: Twenty-five subjects (age: 60 ± 10 years) walked, on average, 11.0 ± 21.9 m more in the 6MWT30 than in the 6MWT20 (p < .05). The walking distance, the number of steps, the energy expenditure and the movement intensity between the 6MWT20 and 6MWT30 was correlated (r = 0.95; r = 0.81; r = 0.91; r = 0.67; respectively, p < .001). The walking distances showed high reliability and were similar between test and re-test in the 6MWT30 (544 ± 72.1 vs. 551 ± 70.5; p < .05; ICC = 0.97) and in the 6MWT20 (533 ± 73.1 vs. 532 ± 59.1; p < .05; ICC = 0.87).Conclusion: The 6MWT20 performance is lower than the 6MWT30 However, this difference is not clinically relevant. Additionally, the 6MWT20 is a valid and reproducible test to assess the functional capacity of middle-aged and older adults.