Towards the importance of minimum toe clearance in level ground walking in a healthy elderly population

Tripping is presumed to be the principal cause for falls during walking. At minimum toe clearance, the potential for trip-related falls is considered to be highest. Thus, controlling minimum toe clearance is essential for walking without tripping. In theory, the central nervous system should therefore give priority to accurate control of the variability in minimumtoe clearance, as compared to other gait parameters, since people tend to onlymodify variability in any given task if it interferes with the task performance. The aimof this study was to determine whether elderly individuals show less increase in variability of minimumtoe clearance during a dual-task condition (where an increase of gait variability is provoked), while allowing a larger range of variability inthe other gait parameters. Forty elderly participants walked back and forth on a 25mlong track for five minutes. They then walked a second time performing an additional cognitive task. Thevariability instride time, stride lengthandminimumtoe clearance as well asdual-task costs of each gait parameter were calculated for each walk. The variability in minimumtoe clearance did not change during dual task-walking, whereas the variability of stride length and stride time increased, showing dual-task costs of about 66% and 84%, respectively. To avoid additional detrimental load on the central nervous system, the modification of task-irrelevant variability may be tolerated during dual-task conditions, whereas minimum toe clearance is controlled with high priority. (C) 2014 Elsevier B. V. All rights reserved.