Walking on a Vertically Oscillating Platform with Simulated Gait Asymmetry

Asymmetric gait is associated with pain, injury, and reduced stability in patient populations. Data from side by side walking suggest that unintentional synchronization with an external cue may reduce gait asymmetry. Two types of asymmetric gait were examined here: (1) mass imbalance between limbs to simulate single limb amputation and (2) restriction of plantarflexion during toe-off to simulate reduced propulsion from neurological impairment. Twenty-five healthy participants walked normally and with simulated gait asymmetry on a custom-designed treadmill that oscillated in the vertical direction via pneumatic actuation (amplitude: 2 cm, frequency: participant’s preferred step frequency). Swing Time Asymmetry (STA) and Phase Coordination Index (PCI) both increased significantly with the application of unilateral mass and plantarflexion restriction (p < 0.001). However, walking with simulated asymmetry did not alter unintentional synchronization with the treadmill motion. Further, oscillation of the treadmill did not improve STA or PCI while walking with simulated asymmetry. Analysis of synchronized step clusters using the Weibull survival function revealed that synchronization with the platform persisted for longer durations when compared with data from side by side walking. These results suggest that walking on a vertically oscillating surface may not be an effective approach for improving gait asymmetry.

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Quantification of Dynamic Excitation Potential of Pedestrian Population Crossing Footbridges

Shock and Vibration ◽

10.1155/2011/403147 ◽

2011 ◽

Vol 18 (4) ◽

pp. 563-577 ◽

Cited By ~ 9

Author(s):

Stana Žcaronivanović ◽

Aleksandar Pavić

Keyword(s):

Real Life ◽

Vertical Direction ◽

Design Guidelines ◽

Vibration Response ◽

Step Frequency ◽

Response Level ◽

Dynamic Excitation ◽

Excitation Potential ◽

Vibration Serviceability ◽

Single Response

Due to their slenderness, many modern footbridges may vibrate significantly under pedestrian traffic. Consequently, the vibration serviceability of these structures under human-induced dynamic loading is becoming their governing design criterion. Many current vibration serviceability design guidelines, concerned with prediction of the vibration in the vertical direction, estimate a single response level that corresponds to an "average" person crossing the bridge with the step frequency that matches a footbridge natural frequency. However, different pedestrians have different dynamic excitation potential, and therefore could generate significantly different vibration response of the bridge structure. This paper aims to quantify this potential by estimating the range of structural vibrations (in the vertical direction) that could be induced by different individuals and the probability of occurrence of any particular vibration level. This is done by introducing the inter- and intra-subject variability in the walking force modelling. The former term refers to inability of a pedestrian to induce an exactly the same force with each step while the latter refers to different forces (in terms of their magnitude, frequency and crossing speed) induced by different people. Both types of variability are modelled using the appropriate probability density functions. The probability distributions were then implemented into a framework procedure for vibration response prediction under a single person excitation. Instead of a single response value obtained using currently available design guidelines, this new framework yields a range of possible acceleration responses induced by different people and a distribution function for these responses. The acceleration ranges estimated are then compared with experimental data from two real-life footbridges. The substantial differences in the dynamic response induced by different people are obtained in both the numerical and the experimental results presented. These results therefore confirm huge variability in different people's dynamic potential to excite the structure. The proposed approach for quantifying this variability could be used as a sound basis for development of new probability-based vibration serviceability assessment procedures for pedestrian bridges.

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Individuals Poststroke Do Not Perceive Their Spatiotemporal Gait Asymmetries as Abnormal

Physical Therapy ◽

10.2522/ptj.20140482 ◽

2015 ◽

Vol 95 (9) ◽

pp. 1244-1253 ◽

Cited By ~ 16

Author(s):

Clinton J. Wutzke ◽

Richard A. Faldowski ◽

Michael D. Lewek

Keyword(s):

Step Length ◽

Gait Pattern ◽

Conscious Awareness ◽

Gait Patterns ◽

Temporal Asymmetry ◽

Gait Asymmetry ◽

Stance Time ◽

The Asymmetry ◽

Asymmetric Gait

Background Following stroke, spatiotemporal gait asymmetries persist into the chronic phases, despite the neuromuscular capacity to produce symmetric walking patterns. This persistence of gait asymmetry may be due to deficits in perception, as the newly established asymmetric gait pattern is perceived as normal. Objective The purpose of this study was to determine the effect of usual overground gait asymmetry on the ability to consciously and unconsciously perceive the presence of gait asymmetry in people poststroke. Design An observational study was conducted. Methods Thirty people poststroke walked overground and on a split-belt treadmill with the belts moving at different speeds (0%–70% difference) to impose varied step length and stance time asymmetries. Conscious awareness and subconscious detection of imposed gait patterns were determined for each participant, and the asymmetry magnitudes at those points were compared with overground gait. Results For both spatial and temporal asymmetry variables, the asymmetry magnitude at the threshold of awareness was significantly greater than the asymmetry present at the threshold of detection or during overground gait. Participants appeared to identify belt speed differences using the type of gait asymmetry they typically exhibited (ie, step length or stance time asymmetries during overground gait). Limitations Very few individuals with severe spatiotemporal asymmetry were tested, and participants were instructed to identify asymmetric belt speeds rather than interlimb movements. Conclusions The data suggest that asymmetry magnitudes need to exceed usual overground levels to reach conscious awareness. Therefore, it is proposed that the spatiotemporal asymmetry that is specific to each participant may need to be augmented beyond what he or she usually has during walking in order to promote awareness of asymmetric gait patterns for long-term correction and learning.

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Association between COMT gene Val158Met heterozygote polymorphism and enhanced brain predicting processes

10.1101/2020.09.26.314732 ◽

2020 ◽

Author(s):

L. Bonetti ◽

N.A. Sedghi ◽

S.E.P. Bruzzone ◽

N.T. Haumann ◽

T. Paunio ◽

...

Keyword(s):

Inferior Frontal Gyrus ◽

Survival Function ◽

Comt Gene ◽

Genetic Mutations ◽

Neural Responses ◽

Nucleotide Polymorphism ◽

Single Nucleotide ◽

Middle Temporal ◽

The Brain ◽

Healthy Participants

AbstractPredicting events in the ever-changing environment is a fundamental survival function intrinsic to the physiology of sensory systems, whose efficiency varies among the population. Even though it is established that a major source of such variations is genetic heritage, there are no studies tracking down auditory predicting processes to genetic mutations. Thus, we examined the neurophysiological responses to deviant stimuli recorded with magnetoencephalography (MEG) in 108 healthy participants carrying different variants of the Val158Met single-nucleotide polymorphism (SNP) within the catechol-O-methyltransferase (COMT) gene, which is responsible for the majority of catecholamines degradation in the prefrontal cortex. Our results showed significant amplitude enhancement of neural responses localized within inferior frontal gyrus, superior and middle temporal cortices to deviant auditory stimuli in heterozygote genotype carriers (Val/Met) vs homozygote (Val/Val and Met/Met) carriers. Integrating neurophysiology and genetics, this study provided new and broader insights into the brain mechanisms underlying optimal deviant detection.

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Error-augmentation gait training to improve gait symmetry in patients with non-traumatic lower limb amputation: A proof-of-concept study

Prosthetics and Orthotics International ◽

10.1177/0309364619843777 ◽

2019 ◽

Vol 43 (4) ◽

pp. 426-433

Author(s):

Paul W Kline ◽

Amanda M Murray ◽

Matthew J Miller ◽

Thomas Fields ◽

Cory L Christiansen

Keyword(s):

Step Length ◽

Gait Training ◽

Limb Amputation ◽

Single Session ◽

Overground Walking ◽

Transtibial Amputation ◽

Time Asymmetry ◽

Gait Symmetry ◽

Stance Time ◽

Training Protocol

Background:Asymmetrical stepping patterns are chronic gait impairment for individuals with non-traumatic lower limb amputation. Persistent gait asymmetries contribute to poor gait efficiency, decreased physical function, and development of secondary orthopedic conditions.Objectives:Evaluate the feasibility and preliminary responsiveness of a treadmill-based, error-augmentation gait training protocol to improve gait symmetry in patients with non-traumatic transtibial amputation.Study design:Single group, pre- and post-test.Methods:The error-augmentation gait training protocol involved walking on a split-belt treadmill with asymmetrical belt speeds for five 3-min sets. Spatiotemporal gait characteristics during overground walking at self-selected and fast walking speeds were assessed prior to, immediately after, and 20 min following the error-augmentation gait training protocol. Outcomes included practicality, implementation feasibility, safety, participant acceptability, and change in gait asymmetry.Results:All four participants completed the error-augmentation gait training protocol as prescribed, without adverse events, and found the intervention to be acceptable. Step length and stance time asymmetry during overground walking changed immediately following the error-augmentation gait training protocol with inconsistent changes retained after a 20 min washout period.Conclusions:A single session of error-augmentation gait training is a feasible and safe intervention to modify gait asymmetry in patients with non-traumatic transtibial amputation. Additional study with larger sample sizes and repeated error-augmentation gait training dosing are warranted.Clinical relevanceGait training using error-augmentation on a split-belt treadmill may modify step length and stance time asymmetry for patients with non-traumatic transtibial amputation, but additional research is needed regarding short- and long-term efficacy. Additional training sessions may be needed to sustain initial changes achieved from a single session.

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Gait asymmetry is associated with performance-based physical function among adults with lower-limb amputation

Physiotherapy Theory and Practice ◽

10.1080/09593985.2021.1990449 ◽

2021 ◽

pp. 1-11

Author(s):

Mayank Seth ◽

Peter C Coyle ◽

Ryan T Pohlig ◽

Emma H Beisheim ◽

John R Horne ◽

...

Keyword(s):

Physical Function ◽

Lower Limb ◽

Lower Limb Amputation ◽

Limb Amputation ◽

Gait Asymmetry

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Gait asymmetry, and bilateral coordination of gait during a six-minute walk test in persons with multiple sclerosis

10.1101/2020.05.13.093161 ◽

2020 ◽

Author(s):

Meir Plotnik ◽

Joanne M. Wagner ◽

Gautam Adusumilli ◽

Amihai Gottlieb ◽

Robert T. Naismith

Keyword(s):

Multiple Sclerosis ◽

Walk Test ◽

Bilateral Coordination ◽

Six Minute Walk Test ◽

Gait Asymmetry ◽

Left And Right ◽

Phase Coordination ◽

Analysis System ◽

Minute Walk ◽

Walking Endurance

AbstractGait impairments in persons with multiple sclerosis (pwMS) underlying reduced walking endurance are still poorly understood. Thus, our objective was to assessed gait asymmetry (GA) and bilateral coordination of gait (BCG), among pwMS during the six-minute walk test (6MWT) and their association with disease severity. For this aim, we recruited ninety-two pwMS (age: 46.6 ± 7.9; 83% females) with a broad range of clinical disability who completed the 6MWT wearing gait analysis system. GA was assessed by comparing left and right swing times, and BCG by using the phase coordination index (PCI). Several functional and subjective gait assessments were performed. Results show that gait is more asymmetric and less coordinated as the disease progresses (p<.0001). Participants with mild MS showed significant better BCG as reflected by lower PCI values in comparison to the other two MS severity groups (severe: p =.001, moderate: p=.02). GA and PCI also deteriorated significantly with time during the 6MWT (p<.0001). GA and PCI (i.e., BCG) show somewhat weaker associations with clinical MS status than associations observed between functional and subjective gait assessments and MS status. Similar to other neurological cohorts, GA and PCI are important parameters to assess and to target in interventions among pwMS.

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Dynamics of a Pedestrian’s Walking Motion Based on the Inverted Pendulum Model

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455418501456 ◽

2018 ◽

Vol 18 (11) ◽

pp. 1850145 ◽

Cited By ~ 1

Author(s):

Lijun Ouyang ◽

TingTing Li ◽

Bin Zhen ◽

Lei Wei

Keyword(s):

Inverted Pendulum ◽

Vertical Direction ◽

Lateral Force ◽

Vertical Vibration ◽

Step Frequency ◽

Inverted Pendulum Model ◽

Pendulum Model ◽

Walking Motion ◽

Vertical Step ◽

The Stability

In this paper, the inverted pendulum model is proposed to describe a pedestrian’s walking motion by considering that the pivot point vibrates periodically up and down. The stability, periodic solutions and oscillations of the inverted pendulum are theoretically investigated, the correctness of which is illustrated by numerical simulations. According to frequency spectrum analysis, the inverted pendulum can exhibit periodically or quasi-periodically stable oscillations. However, we demonstrate that the inverted pendulum will maintain the ratio between the lateral and vertical vibration frequencies near [Formula: see text] as an optimizing selection of stability. The theoretical result agrees with the measurement result for a normal pedestrian such that the lateral step frequency is always half the vertical step frequency, which means that it is feasible and reasonable to describe a pedestrian’s walking motion using the inverted pendulum with the pivot vibrating harmonically in the vertical direction. The inverted pendulum model suggested in this paper could contribute to the study of pedestrian–footbridge interaction, which overcomes the difficulty of directly determining the expression of the lateral force induced by pedestrians.

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Does Subthalamic Deep Brain Stimulation Impact Asymmetry and Dyscoordination of Gait in Parkinson’s Disease?

10.1101/2021.02.21.21251403 ◽

2021 ◽

Author(s):

Deepak K Ravi ◽

Christian R Baumann ◽

Elena Bernasconi ◽

Michelle Gwerder ◽

Niklas König Ignasiak ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Deep Brain Stimulation ◽

Brain Stimulation ◽

Postural Instability ◽

Therapeutic Effects ◽

Gait Disorder ◽

Time Asymmetry ◽

Phase Coordination ◽

Deep Brain

AbstractBackgroundSubthalamic deep brain stimulation is an effective treatment for selected Parkinson’s disease patients. Axial deficits including postural stability and gait characteristics are often altered after surgery, but quantitative gait-related therapeutic effects are poorly described.ObjectiveThe goal of this study was to systematically investigate modifications in asymmetry and dyscoordination of gait six-months post-operatively in patients with Parkinson’s disease, and compare the outcomes with preoperative baseline and to asymptomatic controls.MethodsThirty-two patients with Parkinson’s disease (19 with postural instability and gait disorder type, 13 with tremor-dominant disease) and 51 asymptomatic controls participated. Parkinson patients were tested prior to the surgery in both OFF and ON medication states, and six months post-operatively in the ON stimulation condition. Clinical outcome parameters and medication were compared to preoperative conditions. Asymmetry ratios, phase coordination index, and walking speed were assessed.ResultsPatients’ clinical outcomes as assessed by standard clinical parameters at six-months improved significantly, and levodopa-equivalent daily dosages were significantly decreased. STN-DBS increased step time asymmetry (hedges’ g effect sizes [confidence intervals] between pre- and post-surgery: 0.27 [-0.13,0.73]) and phase coordination index (0.29 [-0.08,0.67]). These effects were higher in the Postural Instability and Gait Disorder subgroup than the Tremor Dominant (step time asymmetry: 0.38 [-0.06,0.90] vs. 0.09 [-0.83,1.0] and phase coordination index: 0.39 [-0.04,0.84] vs. 0.13 [-0.76,0.96]).ConclusionThis study provides objective evidence of how subthalamic deep brain stimulation increases asymmetry and dyscoordination of gait in patients with Parkinson’s disease, and suggests motor subtypes-associated differences in the treatment response.

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Sprinting with an amputation: Some race-based lower-limb step observations

Prosthetics and Orthotics International ◽

10.1177/0309364614532863 ◽

2014 ◽

Vol 39 (4) ◽

pp. 300-306 ◽

Cited By ~ 5

Author(s):

Bryce Dyer ◽

Siamak Noroozi ◽

Philip Sewell

Keyword(s):

Athletic Training ◽

Video Analysis ◽

Lower Limb ◽

Limb Development ◽

Step Length ◽

Step Count ◽

Limb Amputation ◽

Laboratory Setting ◽

Step Frequency ◽

Prosthetic Limb

Background: T44 sprinting with an amputation is still in a state of relative infancy. Future scope for athletic training and prosthetic limb development may be assisted with a better understanding of information derived from T44 athletes when under race-based conditions. Objectives: To investigate the behaviour of step count and step frequency when under competitive conditions. Study design: The study comprises two elements: (1) a video-based analysis of race-based limb-to-limb symmetry and (2) a video-based analysis of race-based step count. Methods: Video analysis of several major events from 1996–2012 are assessed for step count and step limb-to-limb symmetry characteristics. Results: The video analysis highlights limb-to-limb imbalances greater than those indicated in the previous literature. A low step count is determined to be desirable for success in the 100-m event. Conclusion: Future analysis of athletes with a lower-limb amputation would be worthwhile when placed under race-based conditions as the limb-to-limb behaviour is more exaggerated than those seen in typical studies held within a laboratory setting. The within-event behaviour of step counts requires further investigation to establish where these take place or whether it is a cumulative step length issue. Clinical relevance This article increases the understanding of the race-based behaviour of amputee athletes and provides more information to contribute to any discussions on the performance of lower-limb prostheses.

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Does Subthalamic Deep Brain Stimulation Impact Asymmetry and Dyscoordination of Gait in Parkinson’s Disease?

Neurorehabilitation and Neural Repair ◽

10.1177/15459683211041309 ◽

2021 ◽

pp. 154596832110413

Author(s):

Deepak K. Ravi ◽

Christian R. Baumann ◽

Elena Bernasconi ◽

Michelle Gwerder ◽

Niklas K. Ignasiak ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Deep Brain Stimulation ◽

Brain Stimulation ◽

Therapeutic Effects ◽

Time Asymmetry ◽

Objective Evidence ◽

Phase Coordination ◽

Stn Dbs ◽

Deep Brain

Background. Subthalamic deep brain stimulation (STN-DBS) is an effective treatment for selected Parkinson’s disease (PD) patients. Gait characteristics are often altered after surgery, but quantitative therapeutic effects are poorly described. Objective. The goal of this study was to systematically investigate modifications in asymmetry and dyscoordination of gait 6 months postoperatively in patients with PD and compare the outcomes with preoperative baseline and to asymptomatic controls without PD. Methods. A convenience sample of thirty-two patients with PD (19 with postural instability and gait disorder (PIGD) type and 13 with tremor dominant disease) and 51 asymptomatic controls participated. Parkinson patients were tested prior to the surgery in both OFF and ON medication states, and 6-months postoperatively in the ON stimulation condition. Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) I to IV and medication were compared to preoperative conditions. Asymmetry ratios, phase coordination index, and walking speed were assessed. Results. MDS-UPDRS I to IV at 6 months improved significantly, and levodopa equivalent daily dosages significantly decreased. STN-DBS increased step time asymmetry (hedges’ g effect sizes [95% confidence interval] between pre- and post-surgery: .27 [-.13, .73]) and phase coordination index (.29 [-.08, .67]). These effects were higher in the PIGD subgroup than the tremor dominant (step time asymmetry: .38 [-.06, .90] vs .09 [-.83, 1.0] and phase coordination index: .39 [-.04, .84] vs .13 [-.76, .96]). Conclusions. This study provides objective evidence of how STN-DBS increases asymmetry and dyscoordination of gait in patients with PD and suggests motor subtypes‐associated differences in the treatment response.

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