Gait adaptations to awareness and experience of a slip when walking on a cross-slope

Abstract

Falls that occur as a result of a slip are one of the leading causes of injuries, particularly in the elderly population. Previous studies have focused on slips that occur on a flat surface. Slips on a laterally sloping surface are important and may be related to different mechanisms of balance recovery. This type of slip might result in different gait adaptations to those previously described on a flat surface, but these adaptations have not been investigated. The aim of this study was to assess whether, when walking on a cross-slope, young adults adapted their gait when made aware of a potential slip, and having experienced a slip. Gait parameters were compared for three conditions--(1) Normal walking; (2) Walking after being made aware of a potential slip (participants were told that a slip may occur); (3) Walking after experiencing a slip (Participants had already experienced at least one slip induced using a soapy contaminant). Gait parameters were only analysed for trials in which there was no slippery contaminant present on the walkway. Stride length and walking velocity were significantly reduced, and stance duration was significantly greater in the awareness and experience conditions compared to normal walking, with no significant differences in any gait parameters between the awareness and experience conditions. In addition, 46.7% of the slip trials resulted in a fall. This is higher than reported for slips induced on a flat surface, suggesting slips on a cross-slope are more hazardous. This would help explain the more cautious gait patterns observed in both the awareness and experience conditions.

Adaptive gait responses to awareness of an impending slip during treadmill walking

“…Given the influence of the awareness of possible slip on gait pattern, the gait speed might vary between walking conditions, becoming a potential confounding factor. For example, subjects tend to walk more slowly when they anticipate the possible slip hazard than when they do not have such an anticipation while walking on a cross-slope slippery surface [9]. Therefore, the observed adaptive changes in gait pattern between normal and aware walking conditions could be attributed to at least two factors: the awareness of possible slip and the varied walking speed.…”

“…Several techniques have been used to create real-life like slips in a laboratory environment, such as the contaminated surfaces [7][8][9], steel rollers [10], moved force plates [11], movable platforms [12,13], and treadmills [14,15]. Although the approaches of generating slips were various, the experimental protocols were similar among studies.…”

“…Although the approaches of generating slips were various, the experimental protocols were similar among studies. Generally, subjects were instructed that they would initially walk normally without perturbation and later slip perturbations could happen [7][8][9]. Only a few studies examined the effects of the awareness or anticipation of the possible slip perturbation on gait pattern.…”

“…Although some studies reported that awareness alone may not result in changes in temporal gait parameters, such as stance time [8,16] and swing time [8], other studies did find that adults would make significant gait changes when there is a potential risk of slipping during overground walking [7]. The preventive changes include a shortened step length and a reduced foot landing angle [7][8][9]. These alterations are considered features of "cautious gait", and have the potential to reducing the severity of slip or improving subjects' resistance to slips [7,10].…”

“…In previous studies concerning the effect of awareness of potential slip on gait pattern, subjects walked over ground [7,9]. Given the influence of the awareness of possible slip on gait pattern, the gait speed might vary between walking conditions, becoming a potential confounding factor.…”