Comparing the Informative Value of 2-Minute Segments of the 6-Minute Walk Test: Insights into a Prospective Study on Parkinson's Disease.

Gait assessment is key in Parkinson's disease (PD), but the psychometric properties of common tests like the 6-Minute Walk Test (6MWT) are not fully established. Inertial Measurement Units (IMUs) offer objective gait measures, potentially reducing repeated testing. This study evaluated whether the resampling of the first 2 min of the 6MWT (2'6MWT) reflects full-test performance in 43 early-to-mild PD patients (median age 65) at baseline, 1-year, and 2-year follow-ups. A trunk-mounted IMU recorded distance covered, walking duration, stride length, gait speed, cadence, and symmetry. Analysis focused on participants with complete longitudinal data from a multicenter original cohort of 62. Stride length and gait speed (2'6MWT vs. 6MWT) demonstrated strong correlations (r > 0.98), near-perfect agreement, <5% error, and stability across follow-ups; cadence showed slightly more variability. The analysis of consecutive 2-min intervals of the 6MWT revealed stable stride length and gait speed, with modest decreases in distance and cadence over time. Exploratory associations of 2'6MWT and 6MWT with motor severity and cognitive status were consistent. These results indicate the 2'6MWT is a reliable, time-efficient alternative to the full 6MWT for assessing walking capacity in PD, especially in outpatient or fatigue-prone patients. The full 6MWT remains valuable for detecting subtle endurance- or fatigue-related changes.