The effect of cognitive dual tasks on balance during walking in physically fit elderly people.

OBJECTIVE: To evaluate the effect on balance of 3 different cognitive dual tasks performed while walking without and with standardization for gait velocity, and measured with both foot placements and trunk movements. DESIGN: Cross-sectional study. SETTING: Community. PARTICIPANTS: Fifty-nine physically fit elderly people (mean age, 73.5y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Stride length and time variability measured with an electronic walkway, body sway measured with an angular velocity instrument, and gait velocity. RESULTS: Overall, dual tasks resulted in decreased gait velocity (1.46 to 1.23m/s, P<.001), increased stride length (1.4% to 2.6%), and time variability (1.3% to 2.3%) (P<.001), and had no significant effect on body sway. After standardization for gait velocity, the dual tasks were associated with increased body sway (111% to 216% of values during walking without dual task, P<.001) and increased stride length and time variability (41% to 223% increase, P<.001). CONCLUSIONS: In physically fit elderly people, cognitive dual tasks influence balance control during walking directly as well as indirectly through decreased gait velocity. Dual tasks increase stride variability with both mechanisms, but the increase in body sway is only visible after standardization for gait velocity. The decreased gait velocity can be a strategy with which to maintain balance during walking in more difficult circumstances