Control of dynamic stability during adaptation to gait termination on a slippery surface

Abstract

An unexpected slip during gait termination results in a generalised slip response designed to regain stability and prevent a fall. With knowledge of and experience with a slippery surface, locomotor behaviour adapts to proactively diminish the effect of the slip and improve the reactive control during the slip. Our purpose was to examine the organisation of the adaptation to a slippery surface during gait termination. After receiving an unexpected slip during gait termination, participants (N = 8) experienced cued gait termination trials in which they were given knowledge of the surface characteristics (i.e., slippery or non-slippery). The observed strategy used to repeatedly stop on a slippery surface involves proactively diminishing the size of the slip perturbation through a flattened foot at heel contact, anterior shift of the COM, shorter step, stance leg extension and swing limb slowing, as well as improving the reaction to the slippery surface through decreased muscle activity and an appropriate decrease in the braking force generation. The implications of this research are that a combination of knowledge of and experience with a slippery surface enables proactive and reactive adjustments in behaviour to effectively and more safely stop walking on a slippery surface.

Adaptation of gait termination on a slippery surface in Parkinson's disease

“…A flatter foot is a proactive movement in anticipation of a slippery surface 11, 13–17 that reduces shear contact forces. The control group used this strategy to reduce the effect of the slip perturbation.…”

“…Feedforward adaptations include shorter steps onto the slippery surface 11–16 , an increased stability margin 11, 17 , a forward centre of mass (COM) shift 11, 18–20 and a decreased foot-floor angle to reduce shear contact forces 11–14, 16, 17, 20 . Adaptations to feedback-based responses include increases in the subsequent step length 17, 19, 21, 22 and a more stable COM-base of support (BOS) relationship 12, 19 .…”

Effects of wearing gumboots and leather lace-up boots on lower limb muscle activity when walking on simulated underground coal mine surfaces

“…The risk of experiencing a slip (Chambers and Cham, 2007;Lockhart and Kim, 2006;Oates et al, 2010) or trip (Austin et al, 1999) accident is influenced by the shoeesurface interface, particularly at the time of initial contact with the ground and during the pre-swing of the gait cycle. When walking on a level, even surface while wearing everyday footwear, healthy individuals usually make the necessary adjustments to maintain balance in order to avoid a slip or trip (Austin et al, 1999;Chambers and Cham, 2007;Tang et al, 1998).…”

Shoe–Floor Frictional Requirements During Gait after Experiencing an Unexpected Slip

“…It should also be mentioned that the older adults in this study had a significantly higher mass than the young adults, although the effect of increased mass on slip adaptations after slip exposure, if any, is unknown, although Wu et al (2013) found no significant differences in resultant RCOF during walking without slip exposure between obese and non-obese. Previous research has concluded that laboratory subjects should be limited to a single slip if real-world slips are desired due to gait adaptations noted after slipping Oates et al, 2010). However, the ability to generate more than one unexpected slip in a laboratory environment will likely depend on the population of interest.…”