Age-related kinematic changes in late visual-cueing during obstacle circumvention

Abstract

On a daily basis, we are challenged by common environmental obstacles (e.g. street posts) that require simple and often rapid modifications to our gait patterns to avoid collisions. Poor vision appears to be responsible for important reductions in postural stability during gait; and therefore, individuals with impaired vision, such as the elderly, may be at a greater risk of falling, especially under conditions where stepping avoidance strategies may be constrained by the environment. The purpose of the current study was to examine the body segment and eye-gaze reorientation strategy, role of base of support, as well as visual areas of interest attended to by healthy young (YA) and older adults (OA) when only given limited time, one stride, to prepare for an obstacle circumvention task. Six YA and six OA were asked to perform ten walking trials which required them to circumvent an obstacle in their travel path. Participants used one of two avoidance strategies, either lead leg crossing-over trail leg (narrow base of support) or lead leg stepping-out (wide base of support). Results indicate that base of support constraints did not affect segment reorientation sequence in either age group. The general segment reorientation sequence in YA was initiated by trunk yaw and head yaw, followed by gaze and finally, by M-L foot deviation. No trunk roll deviations were observed. In OA, the general segment reorientation sequence was the following: trunk yaw and trunk roll, gaze and finally, M-L foot deviation. No head yaw deviations were observed. Our findings suggest that YA utilized a foot placement strategy to perform the transient change in travel direction while OA relied on a hip strategy. In addition, YA spent more time gazing straight ahead at the obstacle and the wall, while OA spent more time looking at the ground. This strategy indicates that OA use a more cautious strategy to safely avoid the obstacle. Findings from the present work contribute further knowledge regarding locomotor adjustments during a common, and complex, everyday task in young and older adults.

Acquiring visual information for locomotion by older adults: A systematic review

“…Findings from the reviewed studies (Paquette and Vallis, 2010;Petrofsky et al, 2004) confirm locomotion biomechanics to change with age (Bosse et al, 2012;Elble et al, 1991;Judge et al, 1996). Additionally, such changes appear to occur with concurrent adjustments in eye movements and visual focus.…”

“…Kinematic data reported in the reviewed studies suggest that older adults tend to be more cautious during locomotion, as demonstrated by reduced step length and walking speed, presumably to increase gait stability when preparing to avoid an obstacle (Paquette and Vallis, 2010). Walking speed is likely reduced in older adults because of associated prolonged stance time and greater number of steps for a given distance (Petrofsky et al, 2004).…”

“…These studies suggested that older adults view the environment differently to younger adults in terms of the use of central and peripheral vision (Itoh and Fukuda, 2002), and the distribution of viewing points (Itoh and Fukuda, 2002;Paquette and Vallis, 2010).…”

“…When turning, older adults were found to initiate whole body rotation in tandem with the beginning of a saccade to the direction of the turn, followed by head, trunk and feet re-orientation (Paquette and Vallis, 2010). However, if the direction of the turn was indicated shortly before the turn, older adults initiated the segment reorientation via trunk yaw, followed by rapid shifts of gaze, and then medio-lateral feet displacements.…”

Review of safety and mobility issues among older pedestrians

“…In the presence of uneven surfaces, for example, they have been shown to decrease their walking speed and their step length more than younger adults do (Marigold and Patla, 2008). Moreover, older adults have been found to spend more time looking at the ground during obstacle avoidance, whereas younger adults spend more time gazing straight ahead (Paquette and Vallis, 2010). Finally, the maintenance of a large personal space between themselves and other pedestrians is another strategy used by older adults to reduce the risk of bumping into someone and falling (Gérin-Lajoie et al, 2006).…”