Characteristics of stepping over an obstacle in community dwelling older adults under dual-task conditions.

Previous research suggests that older adults may have difficulty attending to simultaneous tasks. This study was conducted to determine how concurrent performance of a secondary cognitive task influences walking and stepping over an obstacle in community dwelling older adults. Twenty-one men and women with a mean age of 73.4 years (S.D.=5.3) participated in the study. Subjects performed a gait task both alone (single-task condition) and in combination with a cognitive task that involved reciting numbers (dual-task condition). In the gait task, each subject walked at his/her fastest speed along a 10-m walkway and stepped over an obstacle designed to simulate a door threshold. Paired t-tests were used to compare gait parameters (10 m gait speed, gait speed during obstacle approach and negotiation, medial-lateral center of pressure excursion and velocity during obstacle negotiation, foot clearance over the obstacle, step length and foot position relative to the obstacle) and cognitive task performance under single and dual-task conditions. Toe-obstacle distance was greater and obstacle-heel distance was reduced under dual-task conditions. Performance of the remaining gait parameters did not change with the addition of a secondary cognitive task. Cognitive task performance decreased under dual-task conditions. These community dwelling older adults demonstrated minimal or no change in measured gait parameters during simultaneous performance of a cognitive task. The observed decrement in cognitive task performance suggests that subjects may have placed a higher priority on gait performance.