Reliability of the 400‐M Usual‐Pace Walk Test as an Assessment of Mobility Limitation in Older Adults

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Abstract
Objectives: To assess the test‐retest reliability of the 400‐m usual‐pace walk test (400‐MWT), and to determine whether the 4‐m walk test predicts inability to walk 400 m. Design: Observational. Setting: Community, 20‐m tract course. Participants: Sixty study participants (aged≥65) were enrolled from the community and met the following eligibility criteria: self‐reported difficulty in two or more of four functional domains (mobility and exercise tolerance, upper extremity function, basic self‐care, higher functional tasks of independent living) and a score of 18 or higher on the Mini‐Mental State Examination. Methods: The 400‐MWT and 4‐m walk test were each repeated within 7 days. Results: The mean age±standard deviation of the study population was 84.3±6.3; 88.3% were women. Nineteen participants (31.7%) failed both 400‐MWTs, and 41 successfully completed both tests (kappa=1). Mean walking speed for the 4‐m test was 0.87±0.18 m/s for those who completed the 400‐MWT and 0.53±0.17 m/s for those who failed (P<.001). The Spearman correlation coefficient between 4‐m and 400‐m walking speeds was 0.93. The estimated area under the receiver operating characteristic curve between 4‐m walking speed and the ability to perform the 400‐MWT was 0.91. The 4‐m gait speed averaged less than 0.6 m/s in 80% of subjects who failed the 400‐MWT. Conclusion: The test‐retest reliability for inability to complete the 400‐MWT is high. Four‐m walking speed is highly predictive of ability to perform the 400‐MWT. These findings may prove useful to future clinical trials and observational studies that involve assessment of mobility limitations in older adults.