Kinesiology Commons^™

Filtering Affects The Calculation Of The Largest Lyapunov Exponent, Peter C. Raffalt, Ben Senderling, Nicholas Stergiou

Journal Articles

The calculation of the largest Lyapunov exponent (LyE) requires the reconstruction of the time series in an N-dimensional state space. For this, the time delay (Tau) and embedding dimension (EmD) are estimated using the Average Mutual Information and False Nearest Neighbor algorithms. However, the estimation of these variables (LyE, Tau, EmD) could be compromised by prior filtering of the time series evaluated. Therefore, we investigated the effect of filtering kinematic marker data on the calculation of Tau, EmD and LyE using several different computational codes. Kinematic marker data were recorded from 37 subjects during treadmill walking and filtered using a …

Step Width Variability As A Discriminator Of Age-Related Gait Changes, Andreas Skiadopoulos, Emily E. Moore, Harlan Sayles, Kendra K. Schmid, Nicholas Stergiou

Journal Articles

Background

There is scientific evidence that older adults aged 65 and over walk with increased step width variability which has been associated with risk of falling. However, there are presently no threshold levels that define the optimal reference range of step width variability. Thus, the purpose of our study was to estimate the optimal reference range for identifying older adults with normative and excessive step width variability.

Methods

We searched systematically the BMC, Cochrane Library, EBSCO, Frontiers, IEEE, PubMed, Scopus, SpringerLink, Web of Science, Wiley, and PROQUEST databases until September 2018, and included the studies that measured step width variability …

Auditory And Visual External Cues Have Different Effects On Spatial But Similar Effects On Temporal Measures Of Gait Variability, Joao R. Vaz, Troy Rand, Jessica Fujan-Hansen, Mukul Mukherjee, Nicholas Stergiou

Journal Articles

Walking synchronized to external cues is a common practice in clinical settings. Several research studies showed that this popular gait rehabilitation tool alters gait variability. There is also recent evidence which suggests that alterations in the temporal structure of the external cues could restore gait variability at healthy levels. It is unknown, however, if such alterations produce similar effects if the cueing modalities used are different; visual or auditory. The modality could affect gait variability differentially, since there is evidence that auditory cues mostly act in the temporal domain of gait, while visual cues act in the spatial domain of …

Acl Injury And Reconstruction Affect Control Of Ground Reaction Forces Produced During A Novel Task That Simulates Cutting Movements, Amelia Lanier, Brian Knarr, Nicholas Stergiou, Lynn Snyder-Mackler, Thomas S. Buchanan

Journal Articles

After anterior cruciate ligament (ACL) injury and reconstruction, biomechanical and neuromuscular control deficits persist and 25% of those who have experienced an ACL injury will experience a second ACL rupture in the first year after returning to sports. There remains a need for improved rehabilitation and the ability to detect an individual's risk of secondary ACL rupture. Nonlinear analysis metrics, such as the largest Lyapunov exponent (LyE) can provide new biomechanical insight in this population by identifying how movement patterns evolve over time. The purpose of this study was to determine how ACL injury, ACL reconstruction (ACLR), and participation in …

Modular Footwear That Partially Offsets Downhill Or Uphill Grades Minimizes The Metabolic Cost Of Human Walking, Prokopios Antonellis, Cory M. Frederick, Arash Mohammadzadeh Gonabadi, Philippe Malcolm

Journal Articles

Walking on different grades becomes challenging on energetic and muscular levels compared to level walking. While it is not possible to eliminate the cost of raising or lowering the centre of mass (COM), it could be possible to minimize the cost of distal joints with shoes that offset downhill or uphill grades. We investigated the effects of shoe outsole geometry in 10 participants walking at 1 m s−1 on downhill, level and uphill grades. Level shoes minimized metabolic rate during level walking (Psecond-order effect < 0.001). However, shoes that entirely offset the (overall) treadmill grade did not minimize the metabolic rate of walking on grades: shoes with a +3° (upward) inclination minimized metabolic rate during downhill walking on a −6° grade, and shoes with a −3° (downward) inclination minimized metabolic rate during uphill walking on a +6° grade (P interaction effect = 0.023). Shoe inclination influenced (distal) ankle joint parameters, including soleus muscle activity, ankle moment and work rate, whereas treadmill grade influenced (whole-body) ground reaction force and COM work rate as well as (distal) ankle joint parameters including tibialis anterior and plantarflexor muscle activity, ankle moment and work rate. Similar modular footwear could be used to minimize joint loads or assist with walking on rolling terrain.

Ankle And Midtarsal Joint Quasi-Stiffness During Walking With Added Mass, Andrew M. Kern, Nikolaos Papachatzis, Jeffrey M. Patterson, Dustin A. Bruening, Kota Z. Takahashi

Journal Articles

Examination of how the ankle and midtarsal joints modulate stiffness in response to increased force demand will aid understanding of overall limb function and inform the development of bio-inspired assistive and robotic devices. The purpose of this study is to identify how ankle and midtarsal joint quasi-stiffness are affected by added body mass during over-ground walking. Healthy participants walked barefoot over-ground at 1.25 m/s wearing a weighted vest with 0%, 15% and 30% additional body mass. The effect of added mass was investigated on ankle and midtarsal joint range of motion (ROM), peak moment and quasi-stiffness. Joint quasi-stiffness was broken …

Locomotor Patterns Change Over Time During Walking On An Uneven Surface, Jenny A. Kent, Joel H. Sommerfeld, Mukul Mukherjee, Kota Z. Takahashi, Nicholas Stergiou

Journal Articles

During walking, uneven surfaces impose new demands for controlling balance and forward progression at each step. It is unknown to what extent walking may be refined given an amount of stride-to-stride unpredictability at the distal level. Here, we explored the effects of an uneven terrain surface on whole-body locomotor dynamics immediately following exposure and after a familiarization period. Eleven young, unimpaired adults walked for 12 min on flat and uneven terrain treadmills. The whole-body center of mass excursion range (COM_exc) and peak velocity (COM_vel), step length and width were estimated. On first exposure to uneven terrain, …

Uneven Terrain Exacerbates The Deficits Of A Passive Prosthesis In The Regulation Of Whole Body Angular Momentum In Individuals With A Unilateral Transtibial Amputation, Jenny A. Kent, Kota Z. Takahashi, Nicholas Stergiou

Journal Articles

Background

Uneven ground is a frequently encountered, yet little-studied challenge for individuals with amputation. The absence of control at the prosthetic ankle to facilitate correction for surface inconsistencies, and diminished sensory input from the extremity, add unpredictability to an already complex control problem, and leave limited means to produce appropriate corrective responses in a timely manner. Whole body angular momentum, L, and its variability across several strides may provide insight into the extent to which an individual can regulate their movement in such a context. The aim of this study was to explore L in individuals with a transtibial amputation, …

The Effects Of Ankle Stiffness On Mechanics And Energetics Of Walking With Added Loads: A Prosthetic Emulator Study, Erica Hedrick, Philippe Malcolm, Jason M. Wilken, Kota Z. Takahashi

Journal Articles

Background: The human ankle joint has an influential role in the regulation of the mechanics and energetics of gait. The human ankle can modulate its joint ‘quasi-stiffness’ (ratio of plantarflexion moment to dorsiflexion displacement) in response to various locomotor tasks (e.g., load carriage). However, the direct effect of ankle stiffness on metabolic energy cost during various tasks is not fully understood. The purpose of this study was to determine how net metabolic energy cost was affected by ankle stiffness while walking under different force demands (i.e., with and without additional load).
Methods: Individuals simulated an amputation by using …

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 …

Coactivation Index Of Children With Congenital Upper Limb Reduction Deficiencies Before And After Using A Wristdriven 3d Printed Partial Hand Prosthesis, Jorge Zuniga, Dimitrios Kastavelis, Jean Peck, Rakesh Srivastava, James E. Pierce, Drew R. Dudley, David A. Salazar, Keaton J. Young, Brian A. Knarr

Journal Articles

Background: Co-contraction is the simultaneous activation of agonist and antagonist muscles that produces forces around a joint. It is unknown if the use of a wrist-driven 3D printed transitional prostheses has any influence on the neuromuscular motor control strategies of the affected hand of children with unilateral upper-limb reduction deficiencies. Thus, the purpose of the current investigation was to examine the coactivation index (CI) of children with congenital upper-limb reduction deficiencies before and after 6 months of using a wrist-driven 3D printed partial hand prosthesis.

Methods: Electromyographic activity of wrist flexors and extensors (flexor carpi ulnaris and extensor …

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

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 …

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 …

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

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 …

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

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 …

Chapter 9: Biomechanics, Nicholas Stergiou, Daniel Blanke, Sara A. Myers, Ka-Chun Siu

Journal Articles

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. By applying

principles from mechanics and engineering, biomechanists are able to study the forces that act on the body and the effects they produce (Bates, 1991). Hay (1973) describes biomechanics as the science that examines forces acting on and within a biological structure and the effects produced by such forces, whereas Alt (1967) describes biomechanics as the science that investigates the effect of internal and external forces on human and animal bodies …

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 …

Hallux Valgus Surgery Affects Kinematic Parameters During Gait, Jitka Klugarova, Miroslav Janura, Zdenek Svoboda, Zdenek Sos, Nicholas Stergiou, Miloslav Klugar

Journal Articles

Background

The aim of our study was to compare spatiotemporal parameters and lower limb and pelvis kinematics during the walking in patients with hallux valgus before and after surgery and in relation to a control group.

Methods

Seventeen females with hallux valgus, who underwent first metatarsal osteotomy, constituted our experimental group. The control group consisted of thirteen females. Kinematic data during walking were obtained using the Vicon MX system.

Findings

Our results showed that hallux valgus before surgery affects spatiotemporal parameters and lower limb and pelvis kinematics during walking. Hallux valgus surgery further increased the differences that were present before …

A Perceptual Motor Intervention Improves Play Behavior In Children With Moderate To Severe Cerebral Palsy, Bridget O. Ryalls, Regina T. Harbourne, Lisa Kelly-Vance, Jordan Wickstrom, Nikolaos Stergiou, Anastasia Kyvelidou

Journal Articles

For children with moderate or severe cerebral palsy (CP), a foundational early goal is independent sitting. Sitting offers additional opportunities for object exploration, play and social engagement. The achievement of sitting coincides with important milestones in other developmental areas, such as social engagement with others, understanding of spatial relationships, and the use of both hands to explore objects. These milestones are essential skills necessary for play behavior. However, little is known about how sitting and play behavior might be affected by a physical therapy intervention in children with moderate or severe CP. Therefore, our overall purpose in this study was …

Mastoid Vibration Affects Dynamic Postural Control During Gait, Jung Chien, Mukul Mukherjee, Nicholas Stergiou

Journal Articles

Our objective was to investigate how manipulating sensory input through mastoid vibration (MV) could affect dynamic postural control during walking, with and without simultaneous manipulation of the visual and the somatosensory systems. We used three levels of MV (none, unilateral, and bilateral) via vibrating elements placed on the mastoid processes. We combined this with the six conditions of the Locomotor Sensory Organization Test (LSOT) paradigm to challenge the visual and somatosensory systems. We hypothesized that MV would affect both amount and temporal structure measures of sway variability during walking and that, in combination with manipulations of the visual and the …

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 …

Increased Minimum Toe Clearance Variability In Patients With Peripheral Arterial Disease, Troy Rand, Shane R. Wurdeman, Jason M. Johanning, Iraklis Pipinos, Sara A. Myers

Journal Articles

Individuals with peripheral arterial disease (PAD) report difficulty walking and experience 73% more falls than their healthy counterparts, but no studies have investigated functional mechanisms contributing to increased falls. Minimum toe clearance (MTC) is the minimum vertical distance between the toe of the swinging leg and the walking surface when the leg is swinging, and decreased values are associated with an increased risk for falls. This study is the first such analysis in patients with PAD. Eighteen individuals with PAD and eighteen healthy controls walked on a treadmill before and after the onset of claudication pain. Mean MTC and the …

Step Activity And Stride-To-Stride Fluctuations Are Negatively Correlated In Individuals With Transtibial Amputation, Jenny A. Kent, Nicholas Stergiou, Shane Wurdeman

Journal Articles

Background

Variability occurs naturally from stride to stride in healthy gait. It has been shown that individuals with lower limb loss have significantly increased stride-to-stride fluctuations during walking. This is considered indicative of movement disorganization and is associated with less healthy movement. Given that lower limb prosthesis users perform on average less physical activity than able bodied individuals, the purpose of this study was to determine whether increased fluctuations also correspond to a reduced level of activity in daily life.

Methods

Twenty-two transtibial amputees wore an activity monitor (Actigraph, Pensacola, FL, USA) for 3 weeks. Lower limb kinematics during treadmill …

Locomotor Sensory Organization Test: How Sensory Conflict Affects The Temporal Structure Of Sway Variability During Gait, Jung Hung Chien, Mukul Mukherjee, Ka-Chun Siu, Nikolaos Stergiou

Journal Articles

When maintaining postural stability temporally under increased sensory conflict, a more rigid response is used where the available degrees of freedom are essentially frozen. The current study investigated if such a strategy is also utilized during more dynamic situations of postural control as is the case with walking. This study attempted to answer this question by using the Locomotor Sensory Organization Test (LSOT). This apparatus incorporates SOT inspired perturbations of the visual and the somatosensory system. Ten healthy young adults performed the six conditions of the traditional SOT and the corresponding six conditions on the LSOT. The temporal structure of …

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 …

Temporal Structure Of Support Surface Translations Drive The Temporal Structure Of Postural Control During Standing, Troy J. Rand, Sara A. Myers, Anastasia Kyvelidou, Mukul Mukherjee

Journal Articles

A healthy biological system is characterized by a temporal structure that exhibits fractal properties and is highly complex. Unhealthy systems demonstrate lowered complexity and either greater or less predictability in the temporal structure of a time series. The purpose of this research was to determine if support surface translations with different temporal structures would affect the temporal structure of the center of pressure (COP) signal. Eight healthy young participants stood on a force platform that was translated in the anteroposterior direction for input conditions of varying complexity: white noise, pink noise, brown noise, and sine wave. Detrended fluctuation analysis was …

Gait Mechanics In Patients With Chronic Obstructive Pulmonary Disease, Jenna M. Yentes, Kendra K. Schmid, Daniel Blanke, Debra J. Romberger, Stephen I. Rennard, Nikolaos Stergiou

Journal Articles

Background

Chronic obstructive pulmonary disease (COPD) is characterized by the frequent association of disease outside the lung. The objective of this study was to determine the presence of biomechanical gait abnormalities in COPD patients compared to healthy controls while well rested and without rest.

Methods

Patients with COPD (N = 17) and aged-matched, healthy controls (N = 21) walked at their self-selected pace down a 10-meter walkway while biomechanical gait variables were collected. A one-minute rest was given between each of the five collected trials to prevent tiredness (REST condition). Patients with COPD then walked at a self-selected pace on …

Six Degree-Of-Freedom Analysis Of Hip, Knee, Ankle And Foot Provides Updated Understanding Of Biomechanical Work During Human Walking, Karl E. Zelik, Kota Z. Takahashi, Gregory S. Sawicki

Journal Articles

Measuring biomechanical work performed by humans and other animals is critical for understanding muscle–tendon function, jointspecific contributions and energy-saving mechanisms during locomotion. Inverse dynamics is often employed to estimate jointlevel contributions, and deformable body estimates can be used to study work performed by the foot. We recently discovered that these commonly used experimental estimates fail to explain whole-body energy changes observed during human walking. By re-analyzing previously published data, we found that about 25% (8 J) of total positive energy changes of/about the body’s center-of-mass and >30% of the energy changes during the Push-off phase of walking were not explained …

Locomotor Sensory Organization Test: A Novel Paradigm For The Assessment Of Sensory Contributions In Gait, Jung Hung Chien, Diderik-Jan 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 to …