Can prior exposure to repeated non-paretic slips improve reactive responses on novel paretic slips among people with chronic stroke?

Abstract

This study examined if people with chronic stroke (PwCS) could adapt following non-paretic overground gait-slips and whether such prior exposure to non-paretic slips could improve reactive responses on novel paretic slip. Forty-nine PwCS were randomly assigned to either adaptation group, which received eight unexpected, overground, nonparetic-side gait-slips followed by two paretic-side slips or a control group, which received two paretic-side slips. Slip outcome, recovery strategies, center of mass (CoM) state stability, post-slip stride length and slipping kinematics were analyzed. The adaptation group demonstrated fall-reduction from first to eighth non-paretic slips, along with improved stability, stride length and slipping kinematics (p < 0.05). Within the adaptation group, on comparing novel slips, paretic-side demonstrated comparable pre-slip stability (p > 0.05); however, lower post-slip stability, increased slip velocity and falls was noted (p < 0.05). There was no difference in any variables between the novel paretic slips of adaptation and control group (p > 0.01). However, there was a rapid improvement on the 2nd slip such that adaptation group demonstrated improved performance from the first to second paretic slip compared to that in the control group (p < 0.01). PwCS demonstrated immediate proactive and reactive adaptation with overground, nonparetic-side gait-slips. However, PwCS did not demonstrate any inter-limb performance gain on the paretic-side after prior nonparetic-side adaptation when exposed to a novel paretic-side slip; but they did show significant positive gains with single slip priming on the paretic-side compared to controls without prior adaptation.Clinical registry number: NCT03205527.

Keywords: Adaptation; Fall-risk; Slip-perturbation; Stroke.

Conflict of interest statement

Conflict of interest The authors declare no conflict of interest.

© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Figures

Fig. 1

Testing protocol used with overground gait slip perturbations shown for both the adaptation and control group. Participants were randomized into either the adaptation or the control group. All participants were made to walk at their natural walking speed before the unexpected gait-slips. The adaptation group received a block of 8 consecutive overground gait-slips under the non-paretic limb (S1–S8). Following those eight slips, participants were made to walk at their natural walking speed until the paretic limb landed on the moveable platform followed by two paretic-side gait-slips. The control group was subjected to two unexpected gait-slip under the paretic limb following few natural walking trials

Fig. 2

Showing (a) falls vs recovery and (b) backward loss of balance (BLOB) vs no loss of balance (NLOB) for the adaptation group during the eight consecutive overground gait-slips under the non-paretic limb. Significant differences(p < 0.05) are indicated by*

Fig. 3

Showing mean and standard deviation for: (a) pre-slip stability at touchdown (TD), (b) post-slip stability at lift off (LO), (c) post-slip stability at recovery step TD, (d) post-slip stride length, (e) maximum heel displacement and (f) maximum heel velocity of the adaptation group during the eight consecutive overground gait slips under the non-paretic limb. Significant differences (p < 0.05) are indicated by*

Fig. 4

Showing (a) falls vs recovery and (b) backward loss of balance (BLOB) vs no loss of balance (NLOB) of both the adaptation group and the control group for non-paretic and paretic overground gait-slips. Significant differences are indicated by*. Solid line indicates difference between trials of the adaptation group, while dotted line indicates difference between trials of the control group

Fig. 5

Showing mean and standard deviation for: (a) pre-slip stability at TD, (b) post-slip stability at TD, and (c) maximum heel velocity of both the adaptation and control group for non-paretic and paretic over ground gait-slips. Significant differences are indicated by*. Solid line indicates difference between trials of the adaptation group, while dotted line indicates difference between trials of the control group