The effect of cognitive tasks on reactive stepping in young and older adults

Background: Divided attention is commonly required in daily life, and to prevent falls, balance must be recovered when a person experiences unexpected perturbations. Previous studies have shown that additional cognitive tasks in postural responses negatively affect automatic postural responses. However, the effect of dual-tasking on reactive stepping performance is still not clearly understood. This study investigated the effect of dual-tasking on reactive stepping induced by a large perturbation in older adults and characterized the effect of dual-tasking by comparison with young adults. Research question: How does the effect of dual-tasking on reactive stepping performance differ between young and older adults? Methods: Twenty-nine older adults and twenty-two young adults were prospectively exposed to external perturbations to induce forward reactive steps. Perturbations were delivered under simple front fixed gaze (singletask condition) and modified Stroop task (dual-task condition). Measures of the time to foot-off and reach stability, step length, velocity, and number of steps were based on force plate data for both the single- and dual-task conditions. Results: Young and older adults showed a delay in foot-off time during the dual-task condition compared with that during the single-task condition. The reach stability time, step length, and number of steps were worse in the dual-task condition than in the single-task condition for older adults, but not for young adults. The deficits in reactive stepping performance during dual-tasking could reflect the reactive balance capacity in real life. Significance: The findings of this study highlight the increased risk of falls with age.