Comparison of the 2-min walk test and the first 2-min performance of the 6-min walk test across walking conditions in subacute stroke

Walking endurance is commonly assessed using the 6-min walk test (6MWT), but its duration may limit repeated assessments in the subacute phase, and shorter alternatives [2-min walk test (2MWT) and first 2-min performance of the 6MWT (2'6MWT)] remain insufficiently characterized across different walking environments. This retrospective observational study examined the measurement properties of 2MWT and 2'6MWT in 20 individuals with subacute stroke under two indoor walking path configurations: a rectangular path (11.5 × 5 m) requiring repeated turns and a 30-m straight path. Test-retest reliability, measurement error, convergent validity, and explanatory capacity were evaluated. Both indices showed excellent test-retest reliability (intraclass correlation coefficient = 0.973-0.988). Measurement error was higher on the rectangular path than on the straight path (minimal detectable change: 22.0-24.3 vs. 15.8-18.9 m). Correlations with the 6MWT were strong (r = 0.936-0.988). The 2MWT distance explained 94 and 95% of the variance in 6MWT distance on the rectangular and straight paths, whereas the 2'6MWT distance explained 77 and 96%. Adding the Berg Balance Scale and Fugl-Meyer Assessment for the lower extremity substantially improved the 2'6MWT model on rectangular path (ΔR2 = 0.15), with minimal changes elsewhere (ΔR2 = 0.008-0.011). These findings suggest that both the 2MWT and 2'6MWT may serve as reliable and valid measures of walking endurance. However, the strength of association varied by walking path configuration, with reduced explanatory power for the 2'6MWT on the rectangular path, suggesting environment-specific influences on performance. Accordingly, interpretation of these endurance tests should account for walking path configuration and dimensions, which should be routinely reported.