Impact of aging on visual reweighting during locomotion

Objectives: The purpose of this study was to investigate the ability of young and old subjects to reweight visual cues while walking at normal and fast speeds. Methods: Ten young (23.49 +/- 4.72) and ten older adults (age 76.22 +/- 3.11) were asked to physically walk straight while viewing a virtual scene in a head-mounted display (HMD) unit under three conditions: no visual perturbation, blank (no visual input), and visual perturbation. Subjects performed the tasks walking at two speeds: preferred self-pace and fast. Variables calculated included trajectory, heading angle, and body segment orientations. Results: In the perturbation condition, the older adults walked with higher segmentation and more deviations of the body's centre of mass. Only the young subjects were affected by the walking speed, with an improved performance when walking fast. Conclusions: Old age affects the ability to re-weight visual information and make postural or locomotor adjustments in real time. The lower errors of the young adults in the fast conditions suggest decreased cortical control of locomotion with increasing speeds. Significance: Visual information presented in real time can impact on balance and mobility in older adults, and thus should be given serious consideration for the purpose of evaluation and intervention. (C) 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.