Biomechanics Commons^™

On The Calculation Of Sample Entropy Using Continuous And Discrete Human Gait Data, John D. Mccamley, William Denton, Peter C. Raffalt, Jennifer M. Yentes

Journal Articles

Sample entropy (SE) has relative consistency using biologically-derived, discrete data >500 data points. For certain populations, collecting this quantity is not feasible and continuous data has been used. The effect of using continuous versus discrete data on SE is unknown, nor are the relative effects of sampling rate and input parameters m (comparison vector length) and r(tolerance). Eleven subjects walked for 10-minutes and continuous joint angles (480 Hz) were calculated for each lower-extremity joint. Data were downsampled (240, 120, 60 Hz) and discrete range-of-motion was calculated. SE was quantified for angles and range-of-motion at all sampling rates and multiple combinations …

Individualization Of Music-Based Rhythmic Auditory Cueing In Parkinson's Disease, Simone Dalla Bella, Dobromir Dotov, Benoît Brady, Valérie Cochen De Cock

Journal Articles

Gait dysfunctions in Parkinson's disease can be partly relieved by rhythmic auditory cueing. This consists in asking patients to walk with a rhythmic auditory stimulus such as a metronome or music. The effect on gait is visible immediately in terms of increased speed and stride length. Moreover, training programs based on rhythmic cueing can have long-term benefits. The effect of rhythmic cueing, however, varies from one patient to the other. Patients’ response to the stimulation may depend on rhythmic abilities, often deteriorating with the disease. Relatively spared abilities to track the beat favor a positive response to rhythmic cueing. On …

Individualization Of Music-Based Rhythmic Auditory Cueing In Parkinson's Disease, Simone Dalla Bella, Dobromir Dotov, Benoit G. Bardy, Valérie Cochen De Cock

Journal Articles

Gait dysfunctions in Parkinson's disease can be partly relieved by rhythmic auditory cueing. This consists in asking patients to walk with a rhythmic auditory stimulus such as a metronome or music. The effect on gait is visible immediately in terms of increased speed and stride length. Moreover, training programs based on rhythmic cueing can have long-term benefits. The effect of rhythmic cueing, however, varies from one patient to the other. Patients’ response to the stimulation may depend on rhythmic abilities, often deteriorating with the disease. Relatively spared abilities to track the beat favor a positive response to rhythmic cueing. On …

Gait Asymmetry In People With Parkinson’S Disease Is Linked To Reduced Integrity Of Callosal Sensorimotor Regions, Brett W. Fling, Carolin Curtze, Fay B. Horak

Journal Articles

Background: Individuals with Parkinson’s disease (PD) often manifest significant temporal and spatial asymmetries of the lower extremities during gait, which significantly contribute to mobility impairments. While the neural mechanisms underlying mobility asymmetries within this population remain poorly understood, recent evidence points to altered microstructural integrity of white matter fiber tracts within the corpus callosum as potentially playing a substantial role.

Objectives: The purpose of this study was to quantify spatial and temporal gait asymmetries as well as transcallosal microstructural integrity of white matter fiber tracts connecting the primary and secondary sensorimotor cortices in people with PD and age-matched control participants. …

The Slippery Slope Between Falling And Recovering: An Examination Of Sensory And Somatic Factors Influencing Recovery After A Slip, Samuel J. Wilson

Electronic Theses and Dissertations

Background: Slips and falls account for large rates of injury and mortality in multiple populations. During an unexpected slip, sensory mechanisms are responsible for signaling the slip to the central nervous system, and a series of corrective responses is generated to arrest the slip and prevent a fall. While previous research has examined the corrective responses elicited, the answer of how these systems break down during a fall remains elusive. Purpose: To examine differences in postural control (slip detection), lower extremity corrective responses (slip recovery), and cortical control of the slip recovery response between individuals who fall and those who …

Prosthetic Energy Return During Walking Increases After 3 Weeks Of Adaptation To A New Device, Samuel F. Ray, Shane R. Wurdeman, Kota Z. Takahashi

Journal Articles

Background: There are many studies that have investigated biomechanical differences among prosthetic feet, but not changes due to adaptation over time. There is a need for objective measures to quantify the process of adaptation for individuals with a transtibial amputation. Mechanical power and work profiles are a primary focus for modern energystorage- and-return type prostheses, which strive to increase energy return from the prosthesis. The amount of energy a prosthesis stores and returns (i.e., negative and positive work) during stance is directly influenced by the user’s loading strategy, which may be sensitive to alterations during the course of an adaptation …

Differences In Walking Mechanics Between A Traditional Walker And The Kb Balance Trainer, Silvia Zanini

Electronic Theses and Dissertations

INTRODUCTION: Millions of individuals with ambulatory difficulties rely on walking aids to maintain independence and mobility. However, users of traditional walkers typically exhibit increased forward lean of their trunk while using the assistive device. The KB Balance Trainer is a new posterior walker designed to facilitate a more erect position during gait. PURPOSE: To compare gait mechanics across three walking conditions: unassisted, using a traditional walker, and using the KB Balance Trainer. METHODS: Seven adults with experience using walkers due to ambulatory difficulties participated in the study. The study consisted of one training session and one gait analysis session. The …

Dynamic Balance Changes Within Three Weeks Of Fitting A New Prosthetic Foot Component, Jenny A. Kent, Nicholas Stergiou, Shane R. Wurdeman

Journal Articles

Balance during walking is of high importance to prosthesis users and may affect walking during baseline observation and evaluation. The aim of this study was to determine whether changes in walking balance occurred during an adaptation period following the fitting of a new prosthetic component.

Margin of stability in the medial-lateral direction (MOSML) and an anterior instability margin (AIM) were used to quantify the dynamic balance of 21 unilateral transtibial amputees during overground walking. Participants trialled two prosthetic feet presenting contrasting movement/balance constraints; a Higher Activity foot similar to that of their own prosthesis, and a Lower Activity foot. Participants …

Patients With Chronic Obstructive Pulmonary Disease Walk With Altered Step Time And Step Width Variability As Compared With Healthy Control Subjects, Jennifer M. Yentes, Stephen I. Rennard, Kendra K. Schmid, Daniel Blanke, Nikolaos Stergiou

Journal Articles

Rationale: Compared with control subjects, patients with chronic obstructive pulmonary disease (COPD) have an increased incidence of falls and demonstrate balance deficits and alterations in mediolateral trunk acceleration while walking. Measures of gait variability have been implicated as indicators of fall risk, fear of falling, and future falls.

Objectives: To investigate whether alterations in gait variability are found in patients with COPD as compared with healthy control subjects.

Methods: Twenty patients with COPD (16 males; mean age, 63.6 ± 9.7 yr; FEV1/FVC, 0.52 ± 0.12) and 20 control subjects (9 males; mean age, 62.5 ± 8.2 yr) walked for 3 …

Walking To A Multisensory Beat, Charlotte Roy, Julien Lagarde, Dobromir Dotov, Simone Dalla Bella

Journal Articles

Living in a complex and multisensory environment demands constant interaction between perception and action. In everyday life it is common to combine efficiently simultaneous signals coming from different modalities. There is evidence of a multisensory benefit in a variety of laboratory tasks (temporal judgement, reaction time tasks). It is less clear if this effect extends to ecological tasks, such as walking. Furthermore, benefits of multimodal stimulation are linked to temporal properties such as the temporal window of integration and temporal recalibration. These properties have been examined in tasks involving single, non-repeating stimulus presentations. Here we investigate the same temporal properties …

The Effects Of An Inclined And Declined Slope On Backward Locomotion: A Kinematic And Electromyographic Analysis Of Retrowalking, Song Dan Vo

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study was to investigate the effects of an inclined and declined slopeon kinematic properties and muscle activation magnitudes. This purpose was achieved by using a +10% grade for inclined backward walking (IBW) and -10% grade for declined backwardwalking (DBW) on a treadmill. Eleven participants (24.6 ± 4.1 yrs, 68.5 ± 14.6 kg, 1.7 ± 0.1 m) were recruited from the UNLV student body and were subject to a three day adaptation protocol to allow them to choose a preferred walking speed and to familiarize themselves with such a novel task. Two consecutive practice days included a …

Dynamic Perception Of Dynamic Affordances: Walking On A Ship At Sea, Hannah Walter, Jeffrey B. Wagman, Nicholas Stergiou, Nurtekin Erkmen, Thomas A. Stoffregen

Journal Articles

Motion of the surface of the sea (waves, and swell) causes oscillatory motion of ships at sea. Generally, ships are longer than they are wide. One consequence of this structural difference is that oscillatory ship motion typically will be greater in roll (i.e., the ship rolling from side to side) than in pitch (i.e., the bow and stern rising and falling). For persons on ships at sea, affordances for walking on the open deck should be differentially influenced by ship motion in roll and pitch. Specifically, the minimum width of a walkable path should be greater when walking along the …

Biologically-Variable Rhythmic Auditory Cues Are Superior To Isochronous Cues In Fostering Natural Gait Variability In Parkinson’S Disease, Dobromir Dotov, S. Bayard, Valérie Cochen De Cock, Christian Geny, Valérie Driss, G. Garrigue, Benoit G. Bardy, Simone Dalla Bella

Journal Articles

Introduction

Method

Effects Of Aging On The Relationship Between Cognitive Demand And Step Variability During Dual-Task Walking, Leslie M. Decker, Fabien Cignetti, Nathaniel Hunt, Jane F. Potter, Nicholas Stergiou, Stephanie A. Studenski

Journal Articles

A U-shaped relationship between cognitive demand and gait control may exist in dual-task situations, reflecting opposing effects of external focus of attention and attentional resource competition. The purpose of the study was twofold: to examine whether gait control, as evaluated from step-to-step variability, is related to cognitive task difficulty in a U-shaped manner and to determine whether age modifies this relationship. Young and older adults walked on a treadmill without attentional requirement and while performing a dichotic listening task under three attention conditions: non-forced (NF), forced-right (FR), and forced-left (FL). The conditions increased in their attentional demand and requirement for …

Mobility Of Individuals With Multiple Sclerosis And The Influence Of Physical Therapy, Brenda L. Davies

Theses & Dissertations

One main purpose was to explore the compensatory gait strategies of individuals with multiple sclerosis (MS). To address this purpose, we quantified the mechanical work generated by the lower extremity joints during walking. The outcomes from this investi­gation suggested that individuals with MS redistribute positive mechanical work during walking to the hip in order to compensate for a reduced ability of the ankle to generate positive mechanical work. Additionally, we also explored the motor control of the ankle as a potential contributing factor to the mobility limitations of individuals with MS. The outcomes from this investigation indicated that individuals with …

Gait Kinematics And Kinetics Are Affected More By Peripheral Arterial Disease Than By Age, Sara A. Myers, Bryon Applequist, Jessie M. Huisinga, Iraklis Pipinos, Jason M. Johanning

Journal Articles

—Peripheral arterial disease (PAD) produces abnormal gait and disproportionately affects older individuals. The current study investigated PAD gait biomechanics in younger (<65 yr) and older (>/=65 yr) subjects. The study included 61 patients with PAD (31 younger, age: 57.4 +/– 5.3 yr, and 30 older, age: 71.9 +/– 5.2 yr) and 52 nondisabled age-matched control subjects. Patients with PAD were tested during pain-free walking and compared with control subjects. Joint kinematics and kinetics (torques) were compared using a 2 x 2 analysis of variance (groups: patients with PAD vs control subjects, age: younger vs older). Patients with PAD had significantly increased ankle and …

Optic Flow Improves Adaptability Of Spatiotemporal Characteristics During Split-Belt Locomotor Adaptation With Tactile Stimulation, Diderik Jan Anthony Eikema, Jung Chien, Nicholas Stergiou, Sara Myers, Melissa Scott-Pandorf, Jacob J. Bloomberg, Mukul Mukherjee

Journal Articles

Human locomotor adaptation requires feedback and feed-forward control processes to maintain an appropriate walking pattern. Adaptation may require the use of visual and proprioceptive input to decode altered movement dynamics and generate an appropriate response. After a person transfers from an extreme sensory environment and back, as astronauts do when they return from spaceflight, the prolonged period required for re-adaptation can pose a significant burden. In our previous paper, we showed that plantar tactile vibration during a split-belt adaptation task did not interfere with the treadmill adaptation however, larger overground transfer effects with a slower decay resulted. Such effects, in …

Plantar Tactile Perturbations Enhance Transfer Of Split-Belt Locomotor Adaptation, Mukul Mukherjee, Diderik Jan Anthony Eikema, Jung Hung Chien, Sara A. Myers, Melissa Scott-Pandorf, Jacob J. Bloomberg, Nikolaos Stergiou

Journal Articles

Patterns of human locomotion are highly adaptive and flexible and depend on the environmental context. Locomotor adaptation requires the use of multisensory information to perceive altered environmental dynamics and generate an appropriate movement pattern. In this study, we investigated the use of multisensory information during locomotor learning. Proprioceptive perturbations were induced by vibrating tactors, placed bilaterally over the plantar surfaces. Under these altered sensory conditions, participants were asked to perform a split-belt locomotor task representative of motor learning. Twenty healthy young participants were separated into two groups: no-tactors (NT) and tactors (TC). All participants performed an overground walking trial, followed …

Mechanisms To Increase Propulsive Force For Individuals Poststroke, Haoyuan Hsiao, Brian A. Knarr, Jill S. Higginson, Stuart A. Binder-Macleod

Journal Articles

Background: Propulsive force generation is critical to walking speed. Trialing limb angle and ankle moment are major contributors to increases in propulsive force during gait. For able-bodied individuals, trailing limb angle contributes twice as much as ankle moment to increases in propulsive force during speed modulation. The aim of this study was to quantify the relative contribution of ankle moment and trailing limb angle to increases in propulsive force for individuals poststroke.

Methods: A biomechanical-based model previously developed for able-bodied individuals was evaluated and enhanced for individuals poststroke. Gait analysis was performed as subjects (N = 24) with …

The Influence Of Push-Off Timing In A Robotic Ankle-Foot Prosthesis On The Energetics And Mechanics Of Walking, Philippe Malcolm, Robert E. Quesada, Joshua M. Caputo, Steven H. Collins

Journal Articles

Background

Robotic ankle-foot prostheses that provide net positive push-off work can reduce the metabolic rate of walking for individuals with amputation, but benefits might be sensitive to push-off timing. Simple walking models suggest that preemptive push-off reduces center-of-mass work, possibly reducing metabolic rate. Studies with bilateral exoskeletons have found that push-off beginning before leading leg contact minimizes metabolic rate, but timing was not varied independently from push-off work, and the effects of push-off timing on biomechanics were not measured. Most lower-limb amputations are unilateral, which could also affect optimal timing. The goal of this study was to vary the timing …

A Neuromechanics-Based Powered Ankle Exoskeleton To Assist Walking Post-Stroke: A Feasibility Study, Kota Z. Takahashi, Michael D. Lewek, Gregory S. Sawicki

Journal Articles

Background: In persons post-stroke, diminished ankle joint function can contribute to inadequate gait propulsion. To target paretic ankle impairments, we developed a neuromechanics-based powered ankle exoskeleton. Specifically, this exoskeleton supplies plantarflexion assistance that is proportional to the user’s paretic soleus electromyography (EMG) amplitude only during a phase of gait when the stance limb is subjected to an anteriorly directed ground reaction force (GRF). The purpose of this feasibility study was to examine the short-term effects of the powered ankle exoskeleton on the mechanics and energetics of gait.

Methods: Five subjects with stroke walked with a powered ankle exoskeleton …

Stride Length-Speed Relationship During Body Weight Supported Running, Carmen Chona

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study was to determine if body weight support influences the stride length-speed relationship. Additionally, the purpose was to determine if impact characteristics of running are influenced by body weight support and speed. Subjects (n=10; 6 female, 4 male) volunteered to participate in this study. All subjects were injury free and were comfortable running on a treadmill for 30 minutes. Subjects ran on a lower body positive (LBPP, Alter-G, G-Trainer) treadmill for 4 conditions of body weight (100, 40, 30 and 20% of body weight) and 4 running speeds (100, 110, 120 and 130% of the preferred …

Gait Initiation Mechanics In Concussed Varsity Athletes, Adam Harper

Theses and Dissertations (Comprehensive)

Concussions are a common and potentially serious injury that affects athletes across multiple sports. More than ever concussions are now at the forefront of sport-related research.

Current research indicates that in a cohort of Canadian junior hockey players examined during the 2009-2010 season showed a rate of concussion at 36.5% of all athletic injuries (Echlin et al., 2010). This rate of concussion injury indicates that proper evaluations and examination tools are key to successful management of concussions. The objective of this study was to determine whether a functional task such as gait initiation is able to quantify stability difference following …

Lower Extremity Kinematics During Walking And Elliptical Training In Individuals With And Without Traumatic Brain Injury, Thad Buster, Judith Burnfield, Adam P. Taylor, Nikolaos Stergiou

Journal Articles

Background and Purpose: Elliptical training may be an option for practicing walking-like activity for individuals with traumatic brain injuries (TBI). Understanding similarities and differences between participants with TBI and neurologically healthy individuals during elliptical trainer use and walking may help guide clinical applications incorporating elliptical trainers.

Methods: Ten participants with TBI and a comparison group of 10 neurologically healthy participants underwent 2 familiarization sessions and 1 data collection session. Kinematic data were collected as participants walked on a treadmill or on an elliptical trainer. Gait-related measures, including coefficient of multiple correlations (a measure of similarity between ensemble joint movement profiles; …

Temporal Structure Of Variability Reveals Similar Control Mechanisms During Lateral Stepping And Forward Walking, Shane R. Wurdeman, Nikolaos Stergiou

Journal Articles

Previous research exploring a lateral stepping gait utilized amount of variability (i.e. coefficient of variation) in the medial-lateral (ML) and anterior-posterior (AP) direction to propose that the central nervous system’s active control over gait in any direction is dependent on the direction of progression. This study sought to further explore this notion through the study of the temporal structure of variability which is reflective of the neuromuscular system’s organization of the movement over time. The largest Lyapunov exponent (LyE) of the reconstructed attractors for the foot’s movement in the AP and ML was calculated. Results revealed that despite the obvious …

Transtibial Amputee Joint Motion Has Increased Attractor Divergence During Walking Compared To Non-Amputee Gait, Shane R. Wurdeman, Sara A. Myers, Nikolaos Stergiou

Journal Articles

The amputation and subsequent prosthetic rehabilitation of a lower leg affects gait. Dynamical systems theory would predict the use of a prosthetic device should alter the functional attractor dynamics to which the system self-organizes. Therefore, the purpose of this study was to compare the largest Lyapunov exponent (a nonlinear tool for assessing attractor dynamics) for amputee gait compared to healthy non-amputee individuals. Fourteen unilateral, transtibial amputees and fourteen healthy, non-amputee individuals ambulated on a treadmill at preferred, self-selected walking speed. Our results showed that the sound hip (p = 0.013), sound knee (p = 0.05), and prosthetic ankle …

Changes In The Activation And Function Of The Ankle Plantar Flexor Muscles Due To Gait Retraining In Chronic Stroke Survivors, Brian A. Knarr, Trisha M. Kesar, Darcy S. Reiman, Stuart A. Binder-Macleod

Journal Articles

Background

A common goal of persons post-stroke is to regain community ambulation. The plantar flexor muscles play an important role in propulsion generation and swing initiation as previous musculoskeletal simulations have shown. The purpose of this study was to demonstrate that simulation results quantifying changes in plantar flexor activation and function in individuals post-stroke were consistent with (1) the purpose of an intervention designed to enhance plantar flexor function and (2) expected muscle function during gait based on previous literature.

Methods

Three-dimensional, forward dynamic simulations were created to determine the changes in model activation and function of the paretic ankle …

Prosthesis Preference Is Related To Stride-To-Stride Fluctuations At The Prosthetic Ankle, Shane R. Wurdeman, Sara A. Myers, Adam L. Jacobsen, Nikolaos Stergiou

Journal Articles

The purpose of this study was to determine the relationship between stride-to-stride fluctuations and prosthesis preference. Thirteen individuals with unilateral, transtibial amputation consented to participate. Individuals walked on a treadmill for 3 min with their prescribed and an alternate prosthesis. Stride-to-stride fluctuations were quantified with the largest Lyapunov exponent (LyE) of each joint flexion/extension time series. The change in the LyE was calculated for each major lower-limb joint for both conditions. Participants indicated preference between the prostheses on a continuous visual analog scale. The change in the LyE was correlated with the degree of preference between the two prostheses at …

External Work Is Deficient In Both Limbs Of Patients With Unilateral Pad, Shane R. Wurdeman, Sara A. Myers, Jason Johanning, Iraklis Pipinos, Nikolaos Stergiou

Journal Articles

External work was utilized to measure differences between the unaffected and the affected limb in patients with unilateral peripheral arterial disease compared to healthy controls. Patients with unilateral peripheral arterial disease have shown deficits in peak joint powers during walking in the unaffected and affected legs. However, no research has detailed the amount of work that is being performed by each leg compared to healthy controls even though such an analysis would provide valuable information on the energy output from the affected and the unaffected legs. Two hypotheses were tested: a) the unaffected and affected leg would perform less work …

Sensitivity Of The Wolf’S And Rosenstein’S Algorithms To Evaluate Local Dynamic Stability From Small Gait Data Sets: Response To Commentaries By Bruijn Et Al., Fabien Cignetti, Leslie M. Decker, Nikolaos Stergiou

Journal Articles

Assessing gait stability using the Largest Lyapunov Exponent (λ₁) has become popular, especially because it may be a key measure in evaluating gait abnormalities in patient populations. However, clinical settings usually involve having small gait data sets and accurate determination of λ₁ estimates from such sets is difficult. In an effort to address this issue, Cignetti et al.2 recently identified that λ₁ estimates using the algorithm of Wolf et al.9 (W-algorithm) were more sensitive than those using the algorithm of Rosenstein et al.7 (R-algorithm) in order to capture age-related …