An interrater reliability study of gait analysis systems with the dual task paradigm in healthy young and older adults

BACKGROUND AND AIMS: One reason for the controversial discussion of whether the dual task (DT) walking paradigm has an added value for diagnosis in clinical conditions might be the use of different gait measurement systems. Therefore, the purpose was 1) to detect DT effects of central gait parameters obtained from five different gait analysis devices in young and old adults, 2) to assess the consistency of the measurement systems, and 3) to determine if the absolut and proportional DT costs (DTC) are greater than the system-measurement error under ST. METHODS: Twelve old (72.2 ± 7.9y) and 14 young adults (28.3 ± 6.2y) walked a 14.7-m distance under ST and DT at a self-selected gait velocity. Interrater reliability, precision of the measurement and sensitivity to change were calculated under ST and DT. RESULTS: An age effect was observed in almost all gait parameters for the ST condition. For DT only differences for stride length (p < .029, ɳ(2)(p) = .239) as well as single and double limb support (p = .036, ɳ(2)(p) = .227; p = .034, ɳ(2)(p) = .218) remained. The measurement systems showed a lower absolute agreement compared to consistency across all systems. CONCLUSIONS: When reporting DT effects, the real changes in performance and random measurement errors should always be accounted for. These findings have strong implications for interpreting DT effects.