The circumvention of obstacles during walking in different environmental contexts: a comparison between older and younger adults.

Avoiding pedestrians is an integral part of our daily activities, yet this locomotor activity has received little attention in gait research. A recent study [Motor Control 2005;9:242] described the motor strategies used by young adults to circumvent an obstruction in different environmental contexts including obstacle movement, certainty about this obstacle movement and auditory distractions. The relationship between normal aging and such locomotor activity within these different environmental contexts, however, is not known. The purpose of this study was thus to compare the walking speed and the personal space-a protective zone preserved around the body-in healthy younger and older adults during obstacle circumvention in the above mentioned environmental contexts. The movements of nine younger adults (24.6+/-4.1 years) and nine older adults (69.7+/-3.2 years) were measured as they circumvented a stationary or moving mannequin with and without initial knowledge of the obstacle's displacements. Participants also had to pay attention to auditory messages, played in half of the trials, and to answer related questions. Results showed that all three environmental factors resulted in decreased gait speed in both groups, but the effect of auditory distractions was greater in older adults. Older adults also increased their personal space more than younger adults while paying attention to messages and they made more mistakes when answering related questions. Therefore, even if such an avoidance task is performed routinely, the increased information processing demanded by the environmental context affected both the motor and cognitive performance of older adults more than that of younger adults.