Life Sciences Commons^™

Reduced Vertical Displacement Of The Center Of Mass Is Not Accompanied By Reduced Oxygen Uptake During Walking, Shane R. Wurdeman, Peter C. Raffalt, Nicholas Stergiou

Journal Articles

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The six determinants of gait proposed that the goal of gait is to minimize vertical displacement of the body’s center of mass (CoM) with the objective to optimize energy expenditure. On the contrary, recent investigations suggest that reduced vertical displacement leads to an increase in energy expenditure. However, these investigations had the included subjects deliberately changing their gait, which could bias the endpoint measures. The present study investigated the effect of reduced vertical displacement of the CoM on oxygen uptake and walking economy without imposing altered gait patterns. This was accomplished by having subjects walk on a curved treadmill and …

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Biomechanics (Chapter 9), Nicholas Stergiou, K.-C. Siu, Sara Myers, Ben Senderling

Journal Articles

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Biomechanics is a discipline. A discipline deals with understanding, predicting, and explaining phenomena within a content domain, and biomechanics is the study of the human body in motion. Kinesiology, the parent discipline of biomechanics, is a science that investigates movement. Biomechanical research in human development focuses on evaluating essential movement patterns across the human life span. Biomechanical analysis is specifically important in quantifying the developmental motor skills and movement patterns such as walking, kicking, jumping, throwing, and catching. Biomechanical research also involves studying the movement patterns of injured and disabled people. Forensic biomechanists are invited to analyze evidence, clarify some …

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Energy Neutral: The Human Foot And Ankle Subsections Combine To Produce Near Zero Net Mechanical Work During Walking, Kota Z. Takahashi, Kate Worster, Dustin A. Bruening

Journal Articles

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The human foot and ankle system is equipped with structures that can produce mechanical work through elastic (e.g., Achilles tendon, plantar fascia) or viscoelastic (e.g., heel pad) mechanisms, or by active muscle contractions. Yet, quantifying the work distribution among various subsections of the foot and ankle can be difficult, in large part due to a lack of objective methods for partitioning the forces acting underneath the stance foot. In this study, we deconstructed the mechanical work production during barefoot walking in a segment-by-segment manner (hallux, forefoot, hindfoot, and shank). This was accomplished by isolating the forces acting within each foot …

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Functional Changes Through The Usage Of 3d-Printed Transitional Prostheses In Children, Jorge Zuniga, Jean Peck, Rakesh Srivastava, James E. Pierce, Drew Dudley, Nicholas T. Than, Nicholas Stergiou

Journal Articles

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Introduction: There is limited knowledge on the use of 3 D-printed transitional prostheses, as they relate to changes in function and strength. Therefore, the purpose of this study was to identify functional and strength changes after usage of 3 D-printed transitional prostheses for multiple weeks for children with upper-limb differences.

Materials and methods: Gross manual dexterity was assessed using the Box and Block Test and wrist strength was measured using a dynamometer. This testing was conducted before and after a period of 24 ± 2.61 weeks of using a 3 D-printed transitional prosthesis. The 11 children (five girls and six …

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Measuring Coupling Of Rhythmical Time Series Using Cross Sample Entropy And Cross Recurrence Quantification Analysis, John D. Mccamley, William Denton, Elizabeth E. Lyden, Jennifer M. Yentes

Journal Articles

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The aim of this investigation was to compare and contrast the use of cross sample entropy (xSE) and cross recurrence quantification analysis (cRQA) measures for the assessment of coupling of rhythmical patterns. Measures were assessed using simulated signals with regular, chaotic, and random fluctuations in frequency, amplitude, and a combination of both. Biological data were studied as models of normal and abnormal locomotor-respiratory coupling. Nine signal types were generated for seven frequency ratios. Fifteen patients with COPD (abnormal coupling) and twenty-one healthy controls (normal coupling) walked on a treadmill at three speeds while breathing and walking were recorded. xSE and …

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Reliability Of A Feedback-Controlled Treadmill Algorithm Dependent On The User's Behavior, Casey Wiens, William Denton, Molly Schieber, Ryan Hartley, Vivien Marmelat, Sara A. Myers, Jennifer M. Yentes

Journal Articles

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he reliability of the treadmill belt speed using a feedback-controlled treadmill algorithm was analyzed in this study. Using biomechanical factors of the participant's walking behavior, an estimated walking speed was calculated and used to adjust the speed of the treadmill. Our proposed algorithm expands on the current hypotheses of feedback-controlled treadmill algorithms and is presented below. Nine healthy, young adults walked on a treadmill controlled by the algorithm for three trials over two days. Each participant walked on the feedback-controlled treadmill for one 16-minute and one five-minute trial during day one and one 16-minute trial during day two. Mean, standard …

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Multifractality, Interactivity, And The Adaptive Capacity Of The Human Movement System: A Perspective For Advancing The Conceptual Basis Of Neurologic Physical Therapy, Jon Cavanaugh, Damian G. Kelty-Stephen, Nicholas Stergiou

Journal Articles

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Background and Purpose:

Physical therapists seek to optimize movement as a means of reducing disability and improving health. The short-term effects of interventions designed to optimize movement ultimately are intended to be adapted for use across various future patterns of behavior, in potentially unpredictable ways, with varying frequency, and in the context of multiple tasks and environmental conditions. In this perspective article, we review and discuss the implications of recent evidence that optimal movement variability, which previously had been associated with adaptable motor behavior, contains a specific complex nonlinear feature known as “multifractality.”

Summary of Key Points:

Multifractal movement fluctuation …

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Human-In-The-Loop Bayesian Optimization Of Wearable Device Parameters, Myunghee Kim, Ye Ding, Philippe Malcolm, Jozefien Speeckaert, Christopher Siviy, Conor J. Walsh

Journal Articles

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The increasing capabilities of exoskeletons and powered prosthetics for walking assistance have paved the way for more sophisticated and individualized control strategies. In response to this opportunity, recent work on human-in-the-loop optimization has considered the problem of automatically tuning control parameters based on realtime physiological measurements. However, the common use of metabolic cost as a performance metric creates significant experimental challenges due to its long measurement times and low signal-to-noise ratio. We evaluate the use of Bayesian optimization—a family of sample-efficient, noise-tolerant, and global optimization methods—for quickly identifying near-optimal control parameters. To manage experimental complexity and provide comparisons against related …

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Dynamics Of Stride Interval Characteristics During Continuous Stairmill Climbing, Peter C. Raffalt, Srikant Vallabhajosula, Jessica J. Renz, Mukul Mukherjee, Nikolaos Stergiou

Journal Articles

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It has been shown that statistical persistence in stride intervals characteristics exist during walking, running and cycling and were speed-dependent among healthy young adults. The purpose of this study was to determine if such statistical persistence in stride time interval, stride length and stride speed also exists during self-paced continuous stairmill climbing and if the strength is dependent on stepping rate. Stride time, stride length, and stride speed were collected from nine healthy participants during 3 min of stairmill climbing at 100, 110, and 120% of their preferred stepping rate (PSR) and 5 min of treadmill walking at preferred walking …

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

Journal Articles

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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 …

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Muscle Strength And Control Characteristics Are Altered By Peripheral Artery Disease, Molly Schieber, Ryan Hasenkamp, Iraklis Pipinos, Jason Johanning, Nicholas Stergiou, Holly Despiegelaere, Jung Chien, Sara A. Myers

Journal Articles

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Objective

Peripheral artery disease (PAD), a common manifestation of atherosclerosis, is characterized by lower leg ischemia and myopathy in association with leg dysfunction. Patients with PAD have impaired gait from the first step they take with consistent defects in the movement around the ankle joint, especially in plantar flexion. Our goal was to develop muscle strength profiles to better understand the problems in motor control responsible for the walking impairment in patients with PAD.

Methods

Ninety-four claudicating PAD patients performed maximal isometric plantar flexion contractions lasting 10 seconds in two conditions: pain free (patient is well rested and has no …

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Gait Deficiencies Associated With Peripheral Artery Disease Are Different Than Chronic Obstructive Pulmonary Disease, John D. Mccamley, Eric J. Pisciotta, Jennifer M. Yentes, Shane R. Wurdeman, Stephen I. Rennard, Iraklis I. Pipinos, Jason M. Johanning, Sara A. Myers

Journal Articles

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Objective: Previous studies have indicated that patients with peripheral artery disease (PAD), display significant differences in their kinetic and kinematic gait characteristics when compared to healthy, aged-matched controls. The ability of patients with chronic obstructive pulmonary disease (COPD) to ambulate is also limited. These limitations are likely due to pathology-driven muscle morphology and physiology alterations establish in PAD and COP, respectively. Gait changes in PAD were compared to gait changes due to COPD to further understand how altered limb muscle due to disease can alter walking patterns. Both groups were independently compared to healthy controls. It was hypothesized that both …

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Varying Negative Work Assistance At The Ankle With A Soft Exosuit During Loaded Walking, Philippe Malcolm, Sangjun Lee, Simon Crea, Christopher Siviy, Fabricio Saucedo, Ignacio Galiana, Fausto A. Panizzolo, Kenneth G. Holt, Conor J. Walsh

Journal Articles

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Background: Only very recently, studies have shown that it is possible to reduce the metabolic rate of unloaded and loaded walking using robotic ankle exoskeletons. Some studies obtained this result by means of high positive work assistance while others combined negative and positive work assistance. There is no consensus about the isolated contribution of negative work assistance. Therefore, the aim of the present study is to examine the effect of varying negative work assistance at the ankle joint while maintaining a fixed level of positive work assistance with a multi-articular soft exosuit.

Methods: We tested eight participants during …

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Muscle Strength And Control Characteristics Are Altered By Peripheral Artery Disease, Molly Schieber, Ryan Hasenkamp, Iraklis Pipinos, Jason Johanning, Nicholas Stergiou, Holly Despiegelaere, Jung Chien, Sara Myers

Journal Articles

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Objective

Peripheral artery disease (PAD), a common manifestation of atherosclerosis, is characterized by lower leg ischemia and myopathy in association with leg dysfunction. Patients with PAD have impaired gait from the first step they take with consistent defects in the movement around the ankle joint, especially in plantar flexion. Our goal was to develop muscle strength profiles to better understand the problems in motor control responsible for the walking impairment in patients with PAD.

Methods

Ninety-four claudicating PAD patients performed maximal isometric plantar flexion contractions lasting 10 seconds in two conditions: pain free (patient is well rested and has …

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Posture And Gaze Tracking Of A Vertically Moving Target Reveals Age-Related Constraints In Visuo-Motor Coupling, Haralampos Sotirakis, Anastasia Kyvelidou, Nicholas Stergiou, Vassilia Hatzitaki

Journal Articles

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Previously we have demonstrated that the effect of aging on posture and gaze active tracking of a visual target moving in the horizontal direction is dependent on target’s complexity. In this study, we asked whether a similar phenomenon is present when tracking a visual target moving with varying complexity in the vertical direction. Ten young (22.98 ± 2.9 years) and 10 older adults (72.45 ± 4.72 years) tracked for 120 s, a visual target moving vertically by shifting their bodyweight in the anterior-posterior direction. Three target motions were tested: a simple periodic (sine wave), a more complex (Lorenz attractor) and …

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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

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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 …

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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, Nicholas Stergiou

Journal Articles

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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 …

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Reliability Of Center Of Pressure Measures For Assessing The Development Of Sitting Postural Control Through The Stages Of Sitting, Jordan Wickstrom, Nicholas Stergiou, Anastasia Kyvelidou

Journal Articles

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Cerebral palsy (CP) impairs an individual’s ability to move and control one’s posture. Unfortunately, the signs and symptoms of CP may not be apparent before age two. Evaluating sitting posture is a potential way to assess the developing mechanisms that contribute to CP. The purpose of this project was to determine the reliability of linear and nonlinear measures, including inter- and intrastage reliability, when used to analyze the center of pressure (COP) time series during the stages of sitting development in children with typical development (TD) and with/at-risk for cerebral palsy (CP). We hypothesized that nonlinear tools would be more …

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Step Activity And 6-Minute Walk Test Outcomes When Wearing Low-Activity Or High-Activity Prosthetic Feet, Shane Wurdeman, Kendra K. Schmid, Sara A. Myers, Adam L. Jacobsen, Nicholas Stergiou

Journal Articles

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Objective

To determine changes in average daily step count (ADSC) and 6-minute walk test (6MWT) due to use of low-activity feet (LA) and high-activity energy-storage-and-return (ESAR) feet, and examine the sensitivity of these measures to properly classify different prosthetic feet.

Design

Individuals with transtibial amputations (n = 28) participated in a 6-week, randomized crossover study. During separate 3-week periods, participants wore either a LA foot (eg, solid-ankle-cushioned-heel) or an ESAR foot. Differences in 6MWT and ADSC at the end of the 3-week period were recorded.

Results

Subjects performed similarly in the 6MWT with the LA and ESAR foot (P …

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Reducing The Metabolic Cost Of Walking With An Ankle Exoskeleton: Interaction Between Actuation Timing And Power, Samuel Galle, Philippe Malcolm, Steven Hartley Collins, Dirk De Clercq

Journal Articles

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Background

Powered ankle-foot exoskeletons can reduce the metabolic cost of human walking to below normal levels, but optimal assistance properties remain unclear. The purpose of this study was to test the effects of different assistance timing and power characteristics in an experiment with a tethered ankle-foot exoskeleton.

Methods

Ten healthy female subjects walked on a treadmill with bilateral ankle-foot exoskeletons in 10 different assistance conditions. Artificial pneumatic muscles assisted plantarflexion during ankle push-off using one of four actuation onset timings (36, 42, 48 and 54% of the stride) and three power levels (average positive exoskeleton power over a stride, summed …

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Children With Moderate To Severe Cerebral Palsy May Not Benefit From Stochastic Vibration When Developing Independent Sitting, Anastasia Kyvelidou, Regina T. Harbourne, Joshua L. Haworth, Kendra K. Schmid, Nicholas Stergiou

Journal Articles

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Purpose: Determine sitting postural control changes for children with cerebral palsy (CP), using a perceptual-motor intervention and the same intervention plus stochastic vibration through the sitting surface. Methods: Two groups of children with moderate or severe CP participated in the 12 week interventions. The primary outcome measure was center of pressure data from which linear and nonlinear variables were extracted and the gross motor function measure (GMFM). Results: There were no significant main effects of intervention or time or an interaction. Both treatment groups increased the Lyapunov exponent values in the medial–lateral direction three months after the …

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Mastoid Vibration Affects Dynamic Postural Control During Gait In Healthy Older Adults, Jung Hung Chien, Mukul Mukherjee, Jenny Kent, Nick Stergiou

Journal Articles

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Vestibular disorders are difficult to diagnose early due to the lack of a systematic assessment. Our previous work has developed a reliable experimental design and the result shows promising results that vestibular sensory input while walking could be affected through mastoid vibration (MV) and changes are in the direction of motion. In the present paper, we wanted to extend this work to older adults and investigate how manipulating sensory input through mastoid vibration (MV) could affect dynamic postural control during walking. Three levels of MV (none, unilateral, and bilateral) applied via vibrating elements placed on the mastoid processes were combined …

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Continuous Sweep Versus Discrete Step Protocols For Studying Effects Of Wearable Robot Assistance Magnitude, Philippe Malcolm, Denise Martineli Rossi, Christopher Siviy, Sangjun Lee, Brendan Thomas Quinlivan, Martin Grimmer, Conor J. Walsh

Journal Articles

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Background: Different groups developed wearable robots for walking assistance, but there is still a need for methods to quickly tune actuation parameters for each robot and population or sometimes even for individual users. Protocols where parameters are held constant for multiple minutes have traditionally been used for evaluating responses to parameter changes such as metabolic rate or walking symmetry. However, these discrete protocols are time-consuming. Recently, protocols have been proposed where a parameter is changed in a continuous way. The aim of the present study was to compare effects of continuously varying assistance magnitude with a soft exosuit against …

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