The effect of a dual-task on obstacle crossing in healthy elderly and young adults

OBJECTIVE: To investigate the effect of a dual-task on step initiation over an obstacle. DESIGN: Repeated-measures design between groups. SETTING: University laboratory. PARTICIPANTS: Ten healthy, community-dwelling elderly adults and 10 healthy young adults. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The effect of a reaction time task on ground reaction forces, toe clearance, and temporal events in stepping over an obstacle. RESULTS: Ground reaction forces of the swing limb before toe-off did not differ between the groups and was not affected by task difficulty. Stepping with a random stimulus after toe-off was the most difficult task, whereas stepping with a predictable stimulus before toe-off was the easiest task. Reaction time and stepping time were greater and toe clearance was less for the elderly subjects. Both groups had a decrease in toe clearance and an increase in reaction time and stepping time as the task became more difficult. CONCLUSIONS: Our findings indicate that even healthy older adults may be at risk for falls in situations where they are engaged in concurrent tasks. The data support the inclusion of dual-task activities in fall prevention programs.