Stepping characteristics during externally induced lateral reactive and voluntary steps in chronic stroke

Abstract

Background: Stepping is critical for responding to perturbations, whether externally induced or self-initiated. Falls post-stroke is equally likely to happen from either mechanism. The objective of the study was, to examine lateral stepping performance during waist-pull induced reactive steps and voluntary choice reaction time steps in chronic stroke and controls. Methods: In this cross-sectional study participants with chronic stroke (N=10) and ageand gender-matched controls (N=10) performed reactive and voluntary lateral steps. Step initiation time, global step length, step clearance, and step velocity were calculated. Other measures for reactive step included, Balance tolerance limit (perturbation magnitude when recovery transitioned from single to multiple steps), and step type. The Community Balance & Mobility Scale, and hip abductor and adductor isokinetic asymmetry torque ratio were assessed. Results: The paretic and non-paretic leg were combined since step characteristics did not differ. Step (voluntary vs. reactive) by group (stroke vs. controls) was significant for step initiation time. The stroke group took longer initiating a voluntary step (P=0.004). Reactive and voluntary steps were executed slower (P=0.041), with a reduced step length (P=0.028) by the stroke group. The stroke group had a lower balance tolerance limit (P=0.01) and took reactive medial steps more frequently (P=0.001). The Community Balance & Mobility Scale (P>0.001), and hip abductor and adductor asymmetry torque ratio (P>0.001; P=0.015) was reduced in the stroke group. Significance: Our findings indicate individuals post-stroke are slower initiating and executing reactive and voluntary steps. Though the reactive step timing is less impaired, this may be a method for enhancing faster voluntary movements and training reactive balance.

Postural control during quiet standing and voluntary stepping response tasks in individuals post-stroke: a case-control study

“…On the other hand, if this recovering step is too short, it may be inadequate to recover balance and force the IPS to use a multistep response to recover, which is known to predispose the individuals with poor postural control to fall. 14 Our results are consistent with those of Gray et al, 22 which found that IPS took longer to initiate a shorter lateral voluntary step compared to controls. Preventing a fall often requires increasing the body's base of support with a quick and fast step to slow down the momentum of the body's COM.…”

“…A comfortable position was used as it allows for a more practical and realistic evaluation of postural control of IPS without changing postural stability compared to a standardised position. 22 Then, participants had to stand on a force plate for 30 seconds and try to move as little as possible with both feet always in contact with the force plate (QS task) until an audio cue appears as a signal to start leaning forward with whole body until they feel they are losing balance and take a step to prevent themselves from falling (VSR task). These two tasks were chosen as they can easily be implemented in clinical contexts with minimal equipment.…”

Characterization of Anticipatory Postural Adjustments in Lateral Stepping: Impact of Footwear and Lower Limb Preference

“…Consequently, most research related to lateral stepping investigated its preparation and execution in specific paradigms, in which participants had to take a step as fast as possible, or in response to a perturbation in an attempt to restore balance [20][21][22]. Nevertheless, lateral steps performed under perturbation conditions are different compared to voluntary ones even when performed as fast as possible [23]; specifically, lateral reactive steps tend to be faster [24] and larger compared to voluntary ones [23]. Therefore, considering the close relationship between preparation and execution of the step [13,25,26], results obtained in reactive or velocity constrained paradigms cannot be generalized to selfpaced voluntary steps.…”

“…Therefore, considering the close relationship between preparation and execution of the step [13,25,26], results obtained in reactive or velocity constrained paradigms cannot be generalized to selfpaced voluntary steps. To our knowledge only a few studies investigated the execution of voluntary lateral stepping [15,23,24,27], although none of them investigated this task in unconstrained conditions.…”

A Perturbation Platform System for Balance Testing and Rehabilitation Interventions

“…Studies have shown promising results in identifying mechanisms underlying balance deficits in several populations utilizing primarily horizontal perturbations. For example, a motor-driven cable system [10] was used to apply a lateral pull to the pelvis to study reactive stepping in older adults [11] and individuals post-stroke [12]. Others have used unexpected forward and backward platform translations to study postural reflexes in individuals post-stroke [13].…”