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Full-Text Articles in Life Sciences

How Do Neighbourhood Definitions Influence The Associations Between Built Environment And Physical Activity?, Suzanne Mavoa, Nasser Bagheri, Mohammad Javad Koohsari, Andrew T. Kaczynski, Karen Elaine Lamb, Koichiro Oka, David O'Sullivan, Karen Witten Jan 2019

How Do Neighbourhood Definitions Influence The Associations Between Built Environment And Physical Activity?, Suzanne Mavoa, Nasser Bagheri, Mohammad Javad Koohsari, Andrew T. Kaczynski, Karen Elaine Lamb, Koichiro Oka, David O'Sullivan, Karen Witten

Faculty of Health Sciences Publications

Researchers investigating relationships between the neighbourhood environment and health first need to decide on the spatial extent of the neighbourhood they are interested in. This decision is an important and ongoing methodological challenge since different methods of defining and delineating neighbourhood boundaries can produce different results. This paper explores this issue in the context of a New Zealand-based study of the relationship between the built environment and multiple measures of physical activity. Geographic information systems were used to measure three built environment attributes—dwelling density, street connectivity, and neighbourhood destination accessibility—using seven different neighbourhood definitions (three administrative unit boundaries ...


Gait Characteristics And Falls In Parkinson's Disease: A Systematic Review And Meta-Analysis [Accepted Manuscript], Mark W. Creaby, Michael H. Cole Dec 2018

Gait Characteristics And Falls In Parkinson's Disease: A Systematic Review And Meta-Analysis [Accepted Manuscript], Mark W. Creaby, Michael H. Cole

Faculty of Health Sciences Publications

Introduction: Given the high rate of falls during walking in people with idiopathic Parkinson's disease (PD), identifying at risk individuals and developing targeted interventions to reduce falls incidence is paramount. Numerous studies have investigated gait-related risk factors for falls in PD, however findings are inconsistent across studies, and thus a synthesis of the current evidence is needed to guide clinical practice and the development of interventions to reduce falls risk. The objective of this study was to systematically review the literature regarding the association between walking biomechanics and falls in people with PD, and where possible, perform meta-analyses. Methods ...


Linking Gait Dynamics To Mechanical Cost Of Legged Locomotion, David V. Lee, Sarah L. Harris Oct 2018

Linking Gait Dynamics To Mechanical Cost Of Legged Locomotion, David V. Lee, Sarah L. Harris

Life Sciences Faculty Publications

For millenia, legged locomotion has been of central importance to humans for hunting, agriculture, transportation, sport, and warfare. Today, the same principal considerations of locomotor performance and economy apply to legged systems designed to serve, assist, or be worn by humans in urban and natural environments. Energy comes at a premium not only for animals, wherein suitably fast and economical gaits are selected through organic evolution, but also for legged robots that must carry sufficient energy in their batteries. Although a robot's energy is spent at many levels, from control systems to actuators, we suggest that the mechanical cost ...


On The Choice Of Multiscale Entropy Algorithm For Quantification Of Complexity In Gait Data, Peter C. Raffalt, William Denton, Jennifer M. Yentes Oct 2018

On The Choice Of Multiscale Entropy Algorithm For Quantification Of Complexity In Gait Data, Peter C. Raffalt, William Denton, Jennifer M. Yentes

Journal Articles

The present study aimed at identifying a suitable multiscale entropy (MSE) algorithm for assessment of complexity in a stride-to-stride time interval time series. Five different algorithms were included (the original MSE, refine composite multiscale entropy (RCMSE), multiscale fuzzy entropy, generalized multiscale entropy and intrinsic mode entropy) and applied to twenty iterations of white noise, pink noise, or a sine wave with added white noise. Based on their ability to differentiate the level of complexity in the three different generated signal types, and their sensitivity and parameter consistency, MSE and RCMSE were deemed most appropriate. These two algorithms were applied to ...


Exoskeleton Assistance Symmetry Matters: Unilateral Assistance Reduces Metabolic Cost, But Relatively Less Than Bilateral Assistance, Philippe Malcolm, Samuel Galle, Pieter Van Den Berghe, Dirk De Clercq Aug 2018

Exoskeleton Assistance Symmetry Matters: Unilateral Assistance Reduces Metabolic Cost, But Relatively Less Than Bilateral Assistance, Philippe Malcolm, Samuel Galle, Pieter Van Den Berghe, Dirk De Clercq

Journal Articles

Background: Many gait impairments are characterized by asymmetry and result in reduced mobility. Exoskeletons could be useful for restoring gait symmetry by assisting only one leg. However, we still have limited understanding of the effects of unilateral exoskeleton assistance. Our aim was to compare the effects of unilateral and bilateral assistance using a within-subject study design.

Methods: Eleven participants walked in different exoskeleton conditions. In the Unilateral conditions, only one leg was assisted. In Bilateral Matched Total Work, half of the assistance from the Unilateral conditions was applied to both legs such that the bilateral sum was equal to that ...


Bi-Articular Knee-Ankle-Foot Exoskeleton Produces Higher Metabolic Cost Reduction Than Weight-Matched Mono-Articular Exoskeleton, Philippe Malcolm, Samuel Galle, Dirk De Clercq Mar 2018

Bi-Articular Knee-Ankle-Foot Exoskeleton Produces Higher Metabolic Cost Reduction Than Weight-Matched Mono-Articular Exoskeleton, Philippe Malcolm, Samuel Galle, Dirk De Clercq

Journal Articles

The bi-articular m. gastrocnemius and the mono-articular m. soleus have different and complementary functions during walking. Several groups are starting to use these biological functions as inspiration to design prostheses with bi-articular actuation components to replace the function of the m. gastrocnemius. Simulation studies indicate that a bi-articular configuration and spring that mimic the m. gastrocnemius could be beneficial for orthoses or exoskeletons. Our aim was to test the effect of a bi-articular and spring configuration that mimics the m. gastrocnemius and compare this to a no- spring and mono-articular configuration. We tested nine participants during walking with knee-ankle-foot exoskeletons ...


Stepping It Up: Walking Behaviors In Children Transitioning From 5th To 7th Grade, Sharon E. Taverno Ross, Morgan N. Clennin, Marsha Dowda, Natalie Colabianchi, Russell R. Pate Feb 2018

Stepping It Up: Walking Behaviors In Children Transitioning From 5th To 7th Grade, Sharon E. Taverno Ross, Morgan N. Clennin, Marsha Dowda, Natalie Colabianchi, Russell R. Pate

Faculty Publications

The purpose of this study was to (1) describe children’s walking behaviors in 5th to 7th grade and change over time and (2) examine associations between walking behaviors and Walk Score®. Participants consisted of n = 586 students from the Transitions and Activity Changes in Kids (TRACK) Study. Children reported any walking behavior (e.g., exercise and transportation) over the past five days. Walk Score was calculated based on children’s home address. Descriptive statistics summarized walking behaviors by gender and time, and repeated measure mixed models examined the relationship between walking behaviors and Walk Score. Approximately 46.8% and ...


Introducing Statistical Persistence Decay – A Quantification Of Stride-To-Stride Time Interval Dependency In Human Gait, P. C. Raffalt, J. M. Yentes Jan 2018

Introducing Statistical Persistence Decay – A Quantification Of Stride-To-Stride Time Interval Dependency In Human Gait, P. C. Raffalt, J. M. Yentes

Journal Articles

Stride-to-stride time intervals during human walking are characterised by predictability and statistical persistence quantified by sample entropy (SaEn) and detrended fluctuation analysis (DFA) which indicates a time dependency in the gait pattern. However, neither analyses quantify time dependency in a physical or physiological interpretable time scale. Recently, entropic half-life (ENT½) has been introduced as a measure of the time dependency on an interpretable time scale. A novel measure of time dependency, based on DFA, statistical persistence decay (SPD), was introduced. The present study applied SaEn, DFA, ENT½, and SPD in known theoretical signals (periodic, chaotic, and random) and stride-to-stride time ...


Development And Reliability Off A Streetscape Observation Instrument For International Use: Maps-Global, Kelli Cain, Carrie M. Geremia, Terry Conway, Lawrence Frank, James Chapman, Eric H. Fox, Anna Timperio, Jenny Veitch, Delfien Van Dyck, Hannah Verhoeven, Rodrigo Reis, Alexande Augusto, Ester Cerin, Robin Mellecker, Ana Queralt, Javier Molina-Garcia, Jim Sallis Jan 2018

Development And Reliability Off A Streetscape Observation Instrument For International Use: Maps-Global, Kelli Cain, Carrie M. Geremia, Terry Conway, Lawrence Frank, James Chapman, Eric H. Fox, Anna Timperio, Jenny Veitch, Delfien Van Dyck, Hannah Verhoeven, Rodrigo Reis, Alexande Augusto, Ester Cerin, Robin Mellecker, Ana Queralt, Javier Molina-Garcia, Jim Sallis

Faculty of Health Sciences Publications

Background: Relationships between several built environment factors and physical activity and walking behavior are well established, but internationally-comparable built environment measures are lacking. The Microscale Audit of Pedestrian Streetscapes (MAPS)-Global is an observational measure of detailed streetscape features relevant to physical activity that was developed for international use. This study examined the inter-observer reliability of the instrument in five countries. Methods: MAPS-Global was developed by compiling concepts and items from eight environmental measures relevant to walking and bicycling. Inter-rater reliability data were collected in neighborhoods selected to vary on geographic information system (GIS)-derived macro-level walkability in five countries ...


A Comparative Evaluation Of Gait Between Children With Autism And Typically Developing Matched Controls, Janet S. Dufek, Jeffrey D. Eggleston, John R. Harry, Robbin Hickman Jan 2017

A Comparative Evaluation Of Gait Between Children With Autism And Typically Developing Matched Controls, Janet S. Dufek, Jeffrey D. Eggleston, John R. Harry, Robbin Hickman

Integrated Health Sciences Faculty Publications

Anecdotal reports suggest children with autism spectrum disorder (ASD) ambulate differently than peers with typical development (TD). Little empirical evidence supports these reports. Children with ASD exhibit delayed motor skills, and it is important to determine whether or not motor movement deficits exist during walking. The purpose of the study was to perform a comprehensive lower-extremity gait analysis between children (aged 5–12 years) with ASD and age- and gender-matched-samples with TD. Gait parameters were normalized to 101 data points and the gait cycle was divided into seven sub-phases. The Model Statistic procedure was used to test for statistical significance ...


Built Environmental Correlates Of Older Adults' Total Physical Activity And Walking: A Systematic Review And Meta-Analysis, David W. Barnett, Anthony Barnett, Andrea Nathan, Jelle Van Cauwenberg, Ester Cerin Jan 2017

Built Environmental Correlates Of Older Adults' Total Physical Activity And Walking: A Systematic Review And Meta-Analysis, David W. Barnett, Anthony Barnett, Andrea Nathan, Jelle Van Cauwenberg, Ester Cerin

Faculty of Health Sciences Publications

Background: Identifying attributes of the built environment associated with health-enhancing levels of physical activity (PA) in older adults (≥65 years old) has the potential to inform interventions supporting healthy and active ageing. The aim of this study was to first systematically review and quantify findings on built environmental correlates of older adults' PA, and second, investigate differences by type of PA and environmental attribute measurement. Methods: One hundred articles from peer-reviewed and grey literature examining built environmentalattributes related to total PA met inclusion criteria and relevant information was extracted. Findings were meta-analysed and weighted by article quality and sample size ...


Sagittal Plane Gait Kinematics In Individuals With Chronic Ankle Instability, Matthew C. Hoch, David R. Mullineaux, Kyoungkyu Jeon, Patrick O. Mckeon Sep 2016

Sagittal Plane Gait Kinematics In Individuals With Chronic Ankle Instability, Matthew C. Hoch, David R. Mullineaux, Kyoungkyu Jeon, Patrick O. Mckeon

Rehabilitation Sciences Faculty Publications

Single joint kinematic alterations have been identified during gait in those with chronic ankle instability (CAI). The purpose of this study was to compare sagittal plane hip, knee, and ankle kinematics during walking in participants with and without CAI. Twelve individuals with CAI and 12 healthy individuals walked on a treadmill at 1.5 m/s. Three-dimensional kinematics were analyzed using mean ensemble curves and independent t tests. Participants with CAI demonstrated less lower extremity flexion during the absorption phase of stance and the limb placement phase of swing, which may have implications for limb placement at initial contact.


Ambulation Speed And Corresponding Mechanics Are Associated With Changes In Serum Cartilage Oligomeric Matrix Protein, W. Matt Denning, Michael Becker Pardo, Jason G. Winward, Iain Hunter, Sarah T. Ridge, J. Ty Hopkins, C. Shane Reese, Allen C. Parcell, Matthew K. Seeley Feb 2016

Ambulation Speed And Corresponding Mechanics Are Associated With Changes In Serum Cartilage Oligomeric Matrix Protein, W. Matt Denning, Michael Becker Pardo, Jason G. Winward, Iain Hunter, Sarah T. Ridge, J. Ty Hopkins, C. Shane Reese, Allen C. Parcell, Matthew K. Seeley

Faculty Publications

Because serum cartilage oligomeric matrix protein (COMP) has been used to reflect articular cartilage condition, we aimed to identify walking and running mechanics that are associated with changes in serum COMP. Eighteen subjects (9 male, 9 female; age = 23 ± 2 yrs.; mass = 68.3 ± 9.6 kg; height = 1.70 ± 0.08 m) completed 4000 steps on an instrumented treadmill on three separate days. Each day corresponded to a different ambulation speed: slow (preferred walking speed), medium (+50% of slow), and fast (+100% of slow). Synchronized ground reaction force and video data were collected to evaluate walking mechanics. Blood samples ...


Can Air Pollution Negate The Health Benefits Of Cycling And Walking?, Marko Tainio, Audrey J. De Nazelle, Thomas Götschi, Sonja Kahlmeier, David Rojas-Rueda, Mark J. Nieuwenhuijsen, Thiago Hérick De Sá, Paul Kelly, James Woodcock Jan 2016

Can Air Pollution Negate The Health Benefits Of Cycling And Walking?, Marko Tainio, Audrey J. De Nazelle, Thomas Götschi, Sonja Kahlmeier, David Rojas-Rueda, Mark J. Nieuwenhuijsen, Thiago Hérick De Sá, Paul Kelly, James Woodcock

Faculty of Health Sciences Publications

Active travel (cycling, walking) is beneficial for the health due to increased physical activity (PA). However, active travel may increase the intake of air pollution, leading to negative health consequences. We examined the risk–benefit balance between active travel related PA and exposure to air pollution across a range of air pollution and PA scenarios. The health effects of active travel and air pollution were estimated through changes in all-cause mortality for different levels of active travel and air pollution. Air pollution exposure was estimated through changes in background concentrations of fine particulate matter (PM2.5), ranging from 5 to ...


Associations Between The Neighbourhood Environment Characteristics And Physical Activity In Older Adults With Specific Types Of Chronic Conditions: The Alecs Cross-Sectional Study, Anthony Barnett, Ester Cerin, Casper J.P. Zhang, Cindy H.P. Sit, Janice M. Johnston, Martin C. Cheung, Ruby S.Y. Lee Jan 2016

Associations Between The Neighbourhood Environment Characteristics And Physical Activity In Older Adults With Specific Types Of Chronic Conditions: The Alecs Cross-Sectional Study, Anthony Barnett, Ester Cerin, Casper J.P. Zhang, Cindy H.P. Sit, Janice M. Johnston, Martin C. Cheung, Ruby S.Y. Lee

Faculty of Health Sciences Publications

Background: Neighbourhood characteristics may influence physical activity (PA), which has positive effects on the health of older adults. Older adults with chronic conditions are less active and possibly more affected by environmental factors than their peers. Understanding neighbourhood characteristics associated with PA specific to older adults with chronic conditions is currently lacking. This cross-sectional study aimed to assess the associations between the neighbourhood environment and various forms of PA in older adults with and without visual impairment, hearing impairment, musculoskeletal disease and/or genitourinary disease. Methods: Neighbourhood environment and PA data were collected in Hong Kong older adults (N = 909 ...


Cognitive And Typing Outcomes Measured Simultaneously With Slow Treadmill Walking Or Sitting: Implications For Treadmill Desks, James D. Lecheminant, Michael D. Larson, Kyle Hill, Kaylie Carbine, Travis Masterson, Ed Christenson Apr 2015

Cognitive And Typing Outcomes Measured Simultaneously With Slow Treadmill Walking Or Sitting: Implications For Treadmill Desks, James D. Lecheminant, Michael D. Larson, Kyle Hill, Kaylie Carbine, Travis Masterson, Ed Christenson

Faculty Publications

Purpose

This study compared cognitive (attention, learning, and memory) and typing outcomes during slow treadmill walking or sitting. Seventy-five healthy individuals were randomly assigned to a treadmill walking group (n=37; 23 female) or sitting group (n=38; 17 female).

Methods

The treadmill walking group completed a series of tests while walking at 1.5 mph. The sitting group performed the same tests while sitting at a standard desk. Tests performed by both groups included: the Rey Auditory Verbal Learning Test and a modified version of the Paced Auditory Serial Attention Test. In addition, typing performance was evaluated.

Results

Participants ...


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 Feb 2015

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 ...


Physical Activity Through Sustainable Transport Approaches (Pasta): Protocol For A Multi-Centre, Longitudinal Study, Evi Dons, Thomas Götschi, Mark J. Nieuwenhuijsen, Audrey De Nazelle, Esther Anaya, Ione Avila-Palencia, Christian Brand, Tom Cole-Hunter, Mailin Gaupp-Berghausen, Sonja Kahlmeier, Michelle Laeremans, Natalie Mueller, Juan Pablo Orjuela, Elisabeth Raser, David Rojas-Rueda, Arnout Standaert, Erik Stigell, Tina Uhlmann, Regine Gerike, Luc Int Panis Jan 2015

Physical Activity Through Sustainable Transport Approaches (Pasta): Protocol For A Multi-Centre, Longitudinal Study, Evi Dons, Thomas Götschi, Mark J. Nieuwenhuijsen, Audrey De Nazelle, Esther Anaya, Ione Avila-Palencia, Christian Brand, Tom Cole-Hunter, Mailin Gaupp-Berghausen, Sonja Kahlmeier, Michelle Laeremans, Natalie Mueller, Juan Pablo Orjuela, Elisabeth Raser, David Rojas-Rueda, Arnout Standaert, Erik Stigell, Tina Uhlmann, Regine Gerike, Luc Int Panis

Faculty of Health Sciences Publications

Background: Physical inactivity is one of the leading risk factors for non-communicable diseases, yet many are not sufficiently active. The Physical Activity through Sustainable Transport Approaches (PASTA) study aims to better understand active mobility (walking and cycling for transport solely or in combination with public transport) as an innovative approach to integrate physical activity into individuals’ everyday lives. The PASTA study will collect data of multiple cities in a longitudinal cohort design to study correlates of active mobility, its effect on overall physical activity, crash risk and exposure to traffic-related air pollution. Methods/Design: A set of online questionnaires incorporating ...


Locomotor Sensory Organization Test: A Novel Paradigm For The Assessment Of Sensory Contributions In Gait, Jung Hung Chien, Diderik Jan Anthony Eikema, Mukul Mukherjee, Nicholas Stergiou Sep 2014

Locomotor Sensory Organization Test: A Novel Paradigm For The Assessment Of Sensory Contributions In Gait, Jung Hung Chien, Diderik Jan Anthony Eikema, Mukul Mukherjee, Nicholas Stergiou

Journal Articles

Feedback based balance control requires the integration of visual, proprioceptive and vestibular input to detect the body’s movement within the environment. When the accuracy of sensory signals is compromised, the system reorganizes the relative contributions through a process of sensory recalibration, for upright postural stability to be maintained. Whereas this process has been studied extensively in standing using the Sensory Organization Test (SOT), less is known about these processes in more dynamic tasks such as locomotion. In the present study, ten healthy young adults performed the six conditions of the traditional SOT to quantify standing postural control when exposed ...


Adaptation And Prosthesis Effects On Stride-To-Stride Fluctuations In Amputee Gait, Shane R. Wurdeman, Sara A. Myers, Adam L. Jacobsen, Nicholas Stergiou Jun 2014

Adaptation And Prosthesis Effects On Stride-To-Stride Fluctuations In Amputee Gait, Shane R. Wurdeman, Sara A. Myers, Adam L. Jacobsen, Nicholas Stergiou

Journal Articles

Twenty-four individuals with transtibial amputation were recruited to a randomized, crossover design study to examine stride-to-stride fluctuations of lower limb joint flexion/extension time series using the largest Lyapunov exponent (λ). Each individual wore a “more appropriate” and a “less appropriate” prosthesis design based on the subject's previous functional classification for a three week adaptation period. Results showed decreased λ for the sound ankle compared to the prosthetic ankle (F1,23 = 13.897, p = 0.001) and a decreased λ for the “more appropriate” prosthesis (F1,23 = 4.849, p = 0.038). There was also a significant ...


Gait Variablility Is Altered In Older Adults When Listening To Auditory Stimuli With Differing Temporal Structures, Jeffrey P. Kaipust, Denise Mcgrath, Mukul Mukherjee, Nicholas Stergiou Aug 2013

Gait Variablility Is Altered In Older Adults When Listening To Auditory Stimuli With Differing Temporal Structures, Jeffrey P. Kaipust, Denise Mcgrath, Mukul Mukherjee, Nicholas Stergiou

Journal Articles

Gait variability in the context of a deterministic dynamical system may be quantified using nonlinear time series analyses that characterize the complexity of the system. Pathological gait exhibits altered gait variability. It can be either too periodic and predictable, or too random and disordered, as it is the case with aging. While gait therapies often focus on restoration of linear measures such as gait speed or stride length, we propose that the goal of gait therapy should be to restore optimal gait variability, which exhibits chaotic fluctuations and is the balance between predictability and complexity. In this context, our purpose ...


Executive Function Orchestrates Regulation Of Task-Relevant Gait Fluctuations, Leslie M. Decker, Fabien Cignetti, Nicholas Stergiou Jul 2013

Executive Function Orchestrates Regulation Of Task-Relevant Gait Fluctuations, Leslie M. Decker, Fabien Cignetti, Nicholas Stergiou

Journal Articles

Humans apply a minimum intervention principle to regulate treadmill walking, rapidly correcting fluctuations in the task-relevant variable (step speed: SS) while ignoring fluctuations in the task-irrelevant variables (step time: ST; step length: SL). We examined whether the regulation of fluctuations in SS and not in ST and SL depends on high-level, executive function, processes. Young adults walked on a treadmill without a cognitive requirement and while performing the cognitive task of dichotic listening. SS fluctuations became less anti-persistent when performing dichotic listening, meaning that taxing executive function impaired the ability to rapidly correct speed deviations on subsequent steps. Conversely, performing ...


Can Sedentary Behavior Be Made More Active? A Randomized Pilot Study Of Tv Commercial Stepping Versus Walking, Jeremy A. Steeves, David R. Bassett, Eugene C. Fitzhugh, Hollie Raynor, Dixie L. Thompson Aug 2012

Can Sedentary Behavior Be Made More Active? A Randomized Pilot Study Of Tv Commercial Stepping Versus Walking, Jeremy A. Steeves, David R. Bassett, Eugene C. Fitzhugh, Hollie Raynor, Dixie L. Thompson

Kinesiology, Recreation, and Sport Studies Publications and Other Works

Background

There is a growing problem of physical inactivity in America, and approximately a quarter of the population report being completely sedentary during their leisure time. In the U.S., TV viewing is the most common leisure-time activity. Stepping in place during TV commercials (TV Commercial Stepping) could increase physical activity. The purpose of this study was to examine the feasibility of incorporating physical activity (PA) into a traditionally sedentary activity, by comparing TV Commercial Stepping during 90 min/d of TV programming to traditional exercise (Walking).

Methods

A randomized controlled pilot study of the impact of 6 months of ...


Sensitivity Of The Wolf’S And Rostein’S Algorithms To Evaluate Local Dynamic Stability From Small Gait Data Sets, Fabien Cignetti, Leslie M. Decker, Nicholas Stergiou May 2012

Sensitivity Of The Wolf’S And Rostein’S Algorithms To Evaluate Local Dynamic Stability From Small Gait Data Sets, Fabien Cignetti, Leslie M. Decker, Nicholas Stergiou

Journal Articles

The Wolf’s (W-algorithm) and Rosenstein’s (R-algorithm) algorithms have been used to quantify local dynamic stability (largest Lyapunov exponent, λ 1) in gait, with prevalence of the latter one that is considered more suitable for small data sets. However, such a claim has never been investigated. To address it, the λ 1 of the Lorenz attractor was estimated using small data sets and varied delays and embedding dimensions. Overall, the λ 1 estimates from the R-algorithm got closer to the theoretical exponent than those from the W-algorithm. The W-algorithm also overestimated λ 1 while ...


Frontal Joint Dynamics When Initiating Stair Ascent From A Walk Versus A Stand, Srikant Vallabhajosula, Jenna M. Yentes, Nicholas Stergiou Feb 2012

Frontal Joint Dynamics When Initiating Stair Ascent From A Walk Versus A Stand, Srikant Vallabhajosula, Jenna M. Yentes, Nicholas Stergiou

Journal Articles

Ascending stairs is a challenging activity of daily living for many populations. Frontal plane joint dynamics are critical to understand the mechanisms involved in stair ascension as they contribute to both propulsion and medio-lateral stability. However, previous research is limited to understanding these dynamics while initiating stair ascent from a stand. We investigated if initiating stair ascent from a walk with a comfortable self-selected speed could affect the frontal plane lower-extremity joint moments and powers as compared to initiating stair ascent from a stand and if this difference would exist at consecutive ipsilateral steps on the stairs. Kinematics data using ...


School Program Planning To Increase Active Transport To School, Brenda Aguilar Jan 2012

School Program Planning To Increase Active Transport To School, Brenda Aguilar

McNair Poster Presentations

Studies have shown that active transport is known to increase physical activity of children, decrease traffic congestion and the production of greenhouse gasses. This study examines active transport to school (ATS) [walking, biking, or other self-powered wheels to school] among elementary students. Through the Nevada Moves Day program an increase proportion of elementary students who use ATS was expected.

This study was done at two elementary schools, one being the intervention school that participated in the Nevada Moves Day, and a control school, which did not participate. Data was collected over a three week period. Students using active transport and ...


New Insights Into Anterior Cruciate Ligament Deficiency And Reconstruction Through The Assessment Of Knee Kinematic Variability In Terms Of Nonlinear Dynamics, Leslie M. Decker, Constantina O. Moraiti, Nicholas Stergiou, Anastasios D. Georgoulis Oct 2011

New Insights Into Anterior Cruciate Ligament Deficiency And Reconstruction Through The Assessment Of Knee Kinematic Variability In Terms Of Nonlinear Dynamics, Leslie M. Decker, Constantina O. Moraiti, Nicholas Stergiou, Anastasios D. Georgoulis

Journal Articles

Purpose

Injuries to the anterior cruciate ligament (ACL) occur frequently, particularly in young adult athletes, and represent the majority of the lesions of knee ligaments. Recent investigations suggest that the assessment of kinematic variability using measures of nonlinear dynamics can provide with important insights with respect to physiological and pathological states. The purpose of the present article was to critically review and synthesize the literature addressing ACL deficiency and reconstruction from a nonlinear dynamics standpoint.

Methods

A literature search was carried out in the main medical databases for studies published between 1990 and 2010.

Results

Seven studies investigated knee kinematic ...


Gait Variability Of Patients With Intermittent Claudication Is Similar Before And After The Onset Of Claudication Pain, Sara A. Myers, Iraklis Pipinos, Jason Johanning, Nicholas Stergiou Aug 2011

Gait Variability Of Patients With Intermittent Claudication Is Similar Before And After The Onset Of Claudication Pain, Sara A. Myers, Iraklis Pipinos, Jason Johanning, Nicholas Stergiou

Journal Articles

Background

Recent research demonstrated that intermittent claudication patients have increased gait variability prior to the onset of claudication. However, it is unknown if these patients experience additional gait adaptations after the onset of claudication. Thus, we sought to determine how gait variability is affected by claudication in an effort to contribute to improved clinical management.

Methods

Twenty-six intermittent claudication patients and 20 controls walked on a treadmill at self-selected speed; intermittent claudication patients were tested before (pain free) and after (pain) the onset of claudication. Variability of the ankle, knee, and hip joint angles was assessed using the largest Lyapunov ...


A Novel Approach To Measure Variability In The Anterior Cruciate Ligament Deficient Knee During Walking: The Use Of The Approximate Entropy In Orthopaedics, Anastasios D. Georgoulis, Constantina O. Moraiti, Stavros Ristanis, Nicholas Stergiou Feb 2006

A Novel Approach To Measure Variability In The Anterior Cruciate Ligament Deficient Knee During Walking: The Use Of The Approximate Entropy In Orthopaedics, Anastasios D. Georgoulis, Constantina O. Moraiti, Stavros Ristanis, Nicholas Stergiou

Journal Articles

Objective. The evaluation of variability of biological rhythmic activities through measures such as Approximate Entropy (ApEn) has provided important information regarding pathology in disciplines such as cardiology and neurology. This research lead to the “loss of complexity hypothesis” where decreased variability is associated with loss of healthy flexibility rendering the system more rigid and unable to adapt to stresses. ApEn as a measure of variability and complexity, correlates well with pathology while, in some cases, it is predictive of subsequent clinical changes. The study of human gait could benefit from the application of ApEn since it is also a rhythmical ...


An Artificial Neural Network That Utilizes Hip Joint Actuations To Control Bifurcations And Chaos In A Passive Dynamic Bipedal Walking Model, Max J. Kurz, Nicholas Stergiou Sep 2005

An Artificial Neural Network That Utilizes Hip Joint Actuations To Control Bifurcations And Chaos In A Passive Dynamic Bipedal Walking Model, Max J. Kurz, Nicholas Stergiou

Journal Articles

Chaos is a central feature of human locomotion and has been suggested to be a window to the control mechanisms of locomotion. In this investigation, we explored how the principles of chaos can be used to control locomotion with a passive dynamic bipedal walking model that has a chaotic gait pattern. Our control scheme was based on the scientific evidence that slight perturbations to the unstable manifolds of points in a chaotic system will promote the transition to new stable behaviors embedded in the rich chaotic attractor. Here we demonstrate that hip joint actuations during the swing phase can provide ...