Lateral Perturbation-Induced Stepping: Strategies and Predictors in Persons Poststroke

Gray, Vicki L.; Yang, Chieh-ling; Waller, Sandy McCombe; Rogers, Mark W.

doi:10.1097/npt.0000000000000202

Cited by 12 publications

(7 citation statements)

References 45 publications

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“…In our previous study, we showed that the hip aductors disciminated the step type that was taken. 15 Similarly, de Kam et al found that a single lateral step recovery required quick and large muscle burst from the hip abductors. 14 This may indicate delays in step initiation may be related to the changes that occur in the hip muscles after a stroke, such as reduced motor units and type II fibers that allow for the motor units to be recruited quickly to initiate movement.…”

Section: Discussionmentioning

confidence: 94%

“…Previously, it has been shown after a stroke that people with impaired sensation are more likely to step with their passively unloaded leg (crossover or medial) but not specifically medial steps. 15 Medial steps may be biomechanically less stabilizing than other step types but may represent a compensatory strategy that limits the base of support adjustment with a shorter first step length, while not requiring comparatively large torques from the hip muscles to recover balance. The findings appear to indicate that people after stroke have a limited capacity to execute a lateral step.…”

Section: Discussionmentioning

confidence: 99%

“…13 In this regard, there is less information on balance recovery in the frontal plane after stroke. 14,15 One would expect balance control in the lateral direction to be more challenging after a stroke because of the asymmetrical distribution of sensory and motor deficits. 5,16 To address these issues, this study examined the influence of a stroke on the spatial-temporal characteristics of stepping in the frontal plane by comparing visually cued voluntary stepping and waist-pull induced reactive stepping, between community-dwelling individuals with chronic stroke and age-and gender-matched healthy controls.…”

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confidence: 99%

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

et al. 2019

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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.

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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

et al. 2019

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“…About 25% of the steps taken during defensive and offensive moves in soccer are in non-forward directions such as backward, diagonal, and lateral directions (Bloomfield et al, 2007 ). Though some studies investigated perturbation-induced steps to forward, backward, and lateral directions (e.g., Tripp et al, 2004 ; Gray et al, 2017 ), only a few studies have investigated the APAs of voluntary non-forward steps. Lyon and Day ( 1997 ) studied the mediolateral postural control before the toe-off of the stepping foot in forward and diagonal steps both experimentally and using simulations.…”

Section: Introductionmentioning

confidence: 99%

Directional Control Mechanisms in Multidirectional Step Initiating Tasks

Inaba

Suzuki

Yoshioka

et al. 2020

Front. Hum. Neurosci.

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Typical anticipatory postural adjustments (APAs) in forward gait or step initiation tasks to prepare for possible disturbances caused by prime voluntary movements and to accelerate the body forward have been previously reported. However, it is not clear how wide the variations in step directions are differentiated and controlled in non-forward step initiation tasks during the APA phase. The main goal of this study is to explain the directional control mechanisms by investigating the APA of step initiation tasks in forward, diagonal, lateral, and posterior directions. The center of pressure (COP) trajectories and related muscle (soleus, tibialis anterior, and gluteus medius of both lower limbs) activities during the APA of step initiation tasks in nine different directions were analyzed in six healthy young males. Posterior shifts of COP during APA decreased as the direction became more lateral (0 • to 90 •). For posterior step initiations, COP moved anteriorly from the initial position to accelerate the center of mass of the whole body (COM) backward. Lateral shifts of COP toward the stepping foot during APA decreased as the stepping direction became more lateral (from 0 • to 45 • and from 180 • to 113 •) while it plateaued to about zero in the direction from 45 • to 113 •. Both anteroposterior and lateral displacements of COP in APA were nonlinearly modulated to each direction, but they were linearly related to the anteroposterior and mediolateral component of the velocities of COM at the takeoff of the stance foot. Thus, the scaling of APA, reflected in the anteroposterior and lateral displacements of COP and the temporal sequence of selected muscle activities, was based on the anteroposterior and mediolateral components of the takeoff velocity of COM that ultimately controls the direction of steps.

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“…Several studies on perturbation stepping in persons post-stroke report a predilection for initiating steps with the less-involved leg, even with lateral perturbations (18–22). Two studies involving steps with the paretic (more-involved) leg with cuing found no difference in step onset or number of steps between paretic and non-paretic (less-involved) legs during these cued reactive stepping tasks (23, 24).…”

Section: Introductionmentioning

confidence: 99%

Perturbation-Induced Stepping Post-stroke: A Pilot Study Demonstrating Altered Strategies of Both Legs

et al. 2019

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Introduction: Asymmetrical sensorimotor function after stroke creates unique challenges for bipedal tasks such as walking or perturbation-induced reactive stepping. Preference for initiating steps with the less-involved (preferred) leg after a perturbation has been reported with limited information on the stepping response of the more-involved (non-preferred) leg. Understanding the capacity of both legs to respond to a perturbation would enhance the design of future treatment approaches. This pilot study investigated the difference in perturbation-induced stepping between legs in stroke participant and non-impaired controls. We hypothesized that stepping performance will be different between groups as well as between legs for post-stroke participants. Methods: Thirty-six participants (20 persons post-stroke, 16 age matched controls) were given an anterior perturbation from three stance positions: symmetrical (SS), preferred asymmetrical (PAS−70% body weight on the preferred leg), and non-preferred asymmetrical (N-PAS−70% body weight on the non-preferred leg). Kinematic and kinetic data were collected to measure anticipatory postural adjustment (APA), characteristics of the first step (onset, length, height, duration), number of steps, and velocity of the body at heel strike. Group differences were tested using the Mann-Whitney U -test and differences between legs tested using the Wilcoxon signed-rank test with an alpha level of 0.05. Results: Stepping with the more-involved leg increased from 11.5% of trials in SS and N-PAS up to 46% in PAS stance position for participants post-stroke. Post-stroke participants had an earlier APA and always took more steps than controls to regain balance. However, differences between post-stroke and control participants were mainly found when stance position was modified. Compare to controls, steps with the preferred leg (N-PAS) were earlier and shorter (in time and length), whereas steps with the non-preferred leg (PAS) were also shorter but took longer. For post-stroke participants, step duration was longer and utilized more steps when stepping with the more-involved leg compared to the less-involved leg. Conclusions: Stepping with the more-involved leg can be facilitated by unweighting the leg. The differences between groups, and legs in post-stroke participants illustrate the simultaneous bipedal role (support and stepping) both legs have in reactive stepping and should be considered for reactive balance training.

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Lateral Perturbation-Induced Stepping: Strategies and Predictors in Persons Poststroke

Cited by 12 publications

References 45 publications

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

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

Directional Control Mechanisms in Multidirectional Step Initiating Tasks

Perturbation-Induced Stepping Post-stroke: A Pilot Study Demonstrating Altered Strategies of Both Legs

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