Purpose: Although gait-related dual-task interference in aging is well established, the effect of locomotor task difficulty on dual-task interference is unknown. This study examined the effect of locomotor task difficulty on dual-task interference in young and older adults.
Methods: Twelve older adults (72.8 years, SD 5.4) and 34 younger adults (21.7 years, SD 1.5) performed three walking tasks of varying levels of difficulty (self-selected speed, fast speed, fast speed with obstacle) under single and dual-task conditions. The cognitive task was the clock task, a visual-spatial reaction time (RT) task. The effects of locomotor task difficulty on dual-task effects on gait speed and RT were examined using a repeated measures mixed model ANOVA. A dual-task cost indicates a decrement in performance under dual-task conditions, whereas a benefit indicates an improvement.
Results: The effect of locomotor task difficulty was significant for both gait speed and RT (p<.05). The dual-task cost on gait speed in the fast walking condition was significantly greater than the dual-task costs on gait speed in self-selected and obstacle crossing tasks (p<.05). Interestingly, there was a dual-task benefit on RT in all conditions. The benefit on RT was significantly greater in the fast walking condition than the other two conditions. The effects of task difficulty were the same for both groups.
Conclusion: Difficulty of the locomotor task influences the dual-task effects on gait speed and RT in both young and older adults. Locomotor task difficulty should be considered when developing dual-task exercise programs for older adults.