Combinations of gait speed testing protocols (automatic vs manual timer, dynamic vs static start) can significantly influence the prevalence of slowness: Results from the Korean Frailty and Aging Cohort Study

This study aimed to compare 4-m usual gait speed obtained with different protocols and to determine the prevalence of slowness using different diagnostic criteria in a large cohort of community-dwelling older adults.A total of 1177 non-disabled community-dwelling older adults aged 70-84 years were assessed for 4-m usual gait speed using four different testing protocols: (1) automatic timer (ultrasonic sensor), dynamic start; (2) manual timer (stopwatch), dynamic start; (3) automatic timer, static start; and (4) manual timer, static start. To assess agreement between usual gait speed and the testing protocols, linear regression and Bland-Altman analyses were performed.There was systematic bias (i.e., difference between automatic timer and manual timer methods), with underestimation of usual gait speed (bias 0.0695 m/s for dynamic start; bias 0.0702 m/s for static start) by the manual timer. There was systematic bias in start conditions, with underestimation of usual gait speed with a static start using both timer methods, compared with that in dynamic start assessment (P < 0.001). The prevalence of slowness ranged from 2.3 to 4.7% in men and 5.9-11.1% in women for <0.80 m/s, and from 17.1 to 30.5% in men and 26.3-45.9% in women for <1.00 m/s.The findings of this study indicated that 4-m usual gait speed measured under different testing protocols was able to determine different prevalence rates of slowness among non-disabled community-dwelling older adults. An automatic timer may be useful for measuring gait speed changes in individuals likely to have faster gait speed in community-based research settings.