Biomechanics Commons^™

Gait Variability Measures Reveal Differences Between Multiple Sclerosis Patients And Healthy Controls, Jeffrey P. Kaipust, Jessie M. Huisinga, Mary Filipi, Nikolaos Stergiou

Journal Articles

The purpose of this study was to determine the differences in gait variability between patients with multiple sclerosis (MS) and healthy controls during walking at a self-selected pace. Methods: Kinematics were collected during three minutes of treadmill walking for 10 patients with MS and 10 healthy controls. The Coefficient of Variation (CoV), the Approximate Entropy (ApEn) and the Detrended Fluctuation Analysis (DFA) were used to investigate the fluctuations present in stride length and step width from continuous strides. Results: ApEn revealed that patients with MS had significantly lower values than healthy controls for stride length (p < .001) and step width (p < .001). Conclusions: ApEn results revealed that the natural fluctuations present during gait in the stride length and step width time series are more regular and repeatable in patients with MS. These changes implied that patients with MS may exhibit reduced capacity to adapt and respond to perturbations during gait.

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

Do Lower-Extremity Joint Dynamics Change When Stair Negotiation Is Initiated With A Self-Selected Comfortable Gait Speed?, Srikant Vallabhajosula, Jenna M. Yentes, Mira Momcilovic, Daniel Blanke, Nikolaos Stergiou

Journal Articles

Previous research on the biomechanics of stair negotiation has ignored the effect of the approaching speed. We examined if initiating stair ascent with a comfortable self-selected speed can affect the lower-extremity joint moments and powers as compared to initiating stair ascent directly in front of the stairs. Healthy young adults ascended a custom-built staircase instrumented with force platforms. Kinematics and kinetics data were collected simultaneously for two conditions: starting from farther away and starting in front of the stairs and analyzed at the first and second ipsilateral steps. Results showed that for the first step, participants produced greater peak knee …

Wearing A Safety Harness During Treadmill Walking Influences Lower Extremity Kinematics Mainly Through Changes In Ankle Regularity And Local Stability, Leslie M. Decker, Fabien Cignetti, Nikolaos Stergiou

Journal Articles

Background: Wearing a harness during treadmill walking ensures the subject’s safety and is common practice in biomedical engineering research. However, the extent to which such practice influences gait is unknown. This study investigated harness-related changes in gait patterns, as evaluated from lower extremity kinematics during treadmill walking.

Findings: Healthy subjects (n = 10) walked on a treadmill at their preferred speed for 3 minutes with and without wearing a harness (LiteGait®, Mobility Research, Inc.). In the former condition, no weight support was provided to the subjects. Lower extremity kinematics was assessed in the sagittal plane from the mean (meanRoM), standard …

Reliability Of Semiautomated Computational Methods For Estimating Tibiofemoral Contact Stress In The Multicenter Osteoarthritis Study, Donald D. Anderson, Neil A. Segal, Andrew M. Kern, Michael C. Nevitt, James C. Torner, John A. Lynch

Journal Articles

Recent findings suggest that contact stress is a potent predictor of subsequent symptomatic osteoarthritis development in the knee. However, much larger numbers of knees (likely on the order of hundreds, if not thousands) need to be reliably analyzed to achieve the statistical power necessary to clarify this relationship. This study assessed the reliability of new semiautomated computational methods for estimating contact stress in knees from large population-based cohorts. Ten knees of subjects from the Multicenter Osteoarthritis Study were included. Bone surfaces were manually segmented from sequential 1.0 Tesla magnetic resonance imaging slices by three individuals on two nonconsecutive days. Four …

Variability Of Gait Is Dependent On Direction Of Progression: Implications For Active Control, Shane R. Wurdeman, Neil B. Huben

Journal Articles

Typical healthy walking displays greater variability in the mediolateral direction compared to the anteroposterior direction. This greater variability is thought to represent increased uncertainty in movement. As a result, it has been postulated that the mediolateral direction of gait requires more active control by the central nervous system while the anteroposterior direction is controlled through passive actions. However, this theory has only been tested on gait where progression occurs in the anteroposterior direction. Therefore, the purpose of this study was to investigate how the amount of variability is affected if progression occurs in the mediolateral direction using a lateral stepping …

An Unstable Shoe With A Rocker Bottom Redistributes External Work, Shane R. Wurdeman, Jenna M. Yentes, Neil B. Huben, Nikolaos Stergiou

Journal Articles

The purpose of this study was to examine the external work performed by individuals wearing a rocker bottom shoe compared to a standard shoe. It was hypothesized that individuals wearing a rocker bottom shoe would have changes in the amount of work over the course of contact with the ground. External work on the body’s centre of mass (BCOM) was calculated for individuals in both conditions. Comparisons for external work were done for positive and negative work for the entire stance phase as well as the initial double support, single support and terminal double support periods. The results revealed that …

Estimates Of Critical Power And Anaerobic Work Capacity From A Single, All-Out Test Of Less Than 3-Min, H C. Bergstrom, T J. Housh, Jorge M. Zuniga, C L. Camic, D A. Traylor, R W. Lewis, R J. Schmidt, G O. Johnson

Journal Articles

The purpose of this study was to determine if Critical Power (CP) and Anaerobic Work Capacity (AWC) could be estimated from a single, all-out test of less than 3-min. Twenty-eight subjects (mean ± SD: age 23.3 ± 3.3 years, body mass 71.6 ± 16 kg) performed an incremental cycle ergometer test to exhaustion to determine peak oxygen consumption rate and heart rate peak. The 3-min all-out test was used to determine the criterion and six estimated values of CP and AWC. The criterion critical power (CP180) and anaerobic work capacity (AWC180) values were determined from the 3-min all-out test and …

Training Dual-Task Walking In Community-Dwelling Adults Within 1 Year Of Stroke: A Protocol For A Single-Blind Randomized Controlled Trial, Prudence Plummer-D'Amato, Anastasia Kyvelidou, Dagmar Sternad, Bijan Najafi, Raymond M. Villalobos, David Zurakowski

Journal Articles

No abstract provided.

Supervised Resistance Training Results In Changes In Postural Control In Patients With Multiple Sclerosis, Jessie M. Huisinga, Mary Filipi, Nikolaos Stergiou

Journal Articles

Postural disturbances are one of the first reported symptoms in patients with Multiple Sclerosis (MS). The purpose of this study was to investigate the effect of supervised resistance training on postural control in MS patients. Postural control was assessed using amount of sway variability [Root Mean Square (RMS)] and temporal structure of sway variability [Lyapunov Exponent (LyE)] from 15 MS patients. Posture was evaluated before and after completion of three months of resistance training. There were significant differences between MS patients pretraining and healthy controls for both LyE (p = .000) and RMS (p = .002), but no differences between …

Endurance Markers Are Related With Local Neuromuscular Response For The Intact But Not For The Acl Reconstructed Leg During High Intensity Running, Kostas Patras, Giorgos Ziogas, Stavros Ristanis, Elias Tsepis, Vasilis Tsiaras, Nikolaos Stergiou, Anastasios D. Georgoulis

Journal Articles

AIM: It has been demonstrated that the local neuromuscular response during high intensity exercise has a strong relationship with endurance markers. However, a diminished neuromuscular response has been reported for the operated leg in athletes having undergone anterior cruciate ligament reconstruction (ACLR). The purpose of the present study was to examine the relationships between endurance markers and the EMG response during high intensity running in ACLR athletes. METHODS: Fourteen ACLR soccer players underwent a GXT test to volitional exhaustion and a 10-min bout of high intensity running. During the 10-min bout, EMG data were recorded at the 3rd …

Human Movement Variability, Nonlinear Dynamics, And Pathology: Is There A Connection?, Nikolaos Stergiou, Leslie M. Decker

Journal Articles

Fields studying movement generation, including robotics, psychology, cognitive science, and neuroscience utilize concepts and tools related to the pervasiveness of variability in biological systems. The concept of variability and the measures for nonlinear dynamics used to evaluate this concept open new vistas for research in movement dysfunction of many types. This review describes innovations in the exploration of variability and their potential importance in understanding human movement. Far from being a source of error, evidence supports the presence of an optimal state of variability for healthy and functional movement. This variability has a particular organization and is characterized by a …

Is There A Relationship Between Fatigue Questionnaires And Gait Mechanics In Persons With Multiple Sclerosis?, Jessie M. Huisinga, Mary Filipi, Kendra K. Schmid, Nikolaos Stergiou

Journal Articles

Objective: To evaluate reported fatigue levels and gait deficits in patients with multiple sclerosis (MS) to determine the relationships that may exist between fatigue in patients with MS and alterations in gait mechanics.

Design: Cross-sectional.

Setting: Biomechanics laboratory.

Participants: Subjects with MS (n=32) and age- and sex-matched controls (n=30).

Interventions: None.

Main Outcome Measures: Fatigue Severity Scale (FSS), Modified Fatigue Index Scale (MFIS), and 36-Item Short Form Health Survey (SF-36) to assess fatigue and general health. Biomechanical gait analysis was performed to measure peak joint torques and powers in the sagittal plane at the ankle, knee, and hip. Correlations …

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, Nikolaos 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 …

From The W-Method To The Canonical-Dissipative Method For Studying Uni-Manual Rhythmic Behavior, Dobromir Dotov, Till D. Frank

Journal Articles

A novel method for the analysis of repetitive limb behavior oscillation is presented. It is based on a model used to account for self-sustained limit cycles that involve energy pumping compensating for dissipative processes. The experiment involved a uni-manual pendulum swinging task paced at five frequencies. The median frequency corresponded to the resonant one for the chosen pendulum and hand parameters. We applied the model-based analysis to explore the relationship between behavioral observables and model parameters not available from previous methods. Oscillation amplitude and energy, and motor variability were the behavioral observables we focused on while energy pumping, attractor strength, …

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

Knee Braces Can Decrease Tibial Rotation During Pivoting That Occurs In High Demanding Activities, Dimitrios Giotis, Vasilios Tsiaras, Stavros Ristanis, Franceska Zampeli, Grigoris Mitsionis, Nikolaos Stergiou, Anastasios D. Georgoulis

Journal Articles

Purpose

The purpose of this study was to investigate whether knee braces could effectively decrease tibial rotation during high demanding activities.

Methods

Using an in vivo three-dimensional kinematic analysis, 21 physically active, healthy, male subjects were evaluated. Each subject performed two tasks that were used extensively in the literature because they combine increased rotational and translational loads on the knee, (1) descending from a stair and subsequent pivoting and (2) landing from a platform and subsequent pivoting under three conditions: (A) wearing a prophylactic brace (braced), (B) wearing a patellofemoral brace (sleeved), and (C) unbraced condition.

Results

In the first …

Complexity, Coordination, And Health: Avoiding Pitfalls And Erroneous Interpretations In Fractal Analyses, Vivien Marmelat, Didier Delignières

Journal Articles

Background and Objective. The analysis of fractal fluctuation has become very popular because of the close relationships between health, adaptability, and long-range correlations. 1/f noise is considered a “magical” threshold, characterizing optimal functioning, and a decrease or conversely and increase of serial correlations, with respect to 1/f noise, is supposed to sign a kind of disadaptation of the system. Empirical results, however, should be interpreted with caution. In experimental series, serial correlations often present a complex pattern, resulting from the combination of long-range and short-term correlated processes. We show, in the present paper, that an increase in serial correlations …

Sensory Information Utilization And Time Delays Characterize Motor Developmental Pathology In Infant Sitting Postural Control, Joan E. Deffeyes, Regina T. Harbourne, Wayne A. Stuberg, Nikolaos Stergiou

Journal Articles

Sitting is one of the first developmental milestones that an infant achieves. Thus measurements of sitting posture present an opportunity to assess sensorimotor development at a young age. Sitting postural sway data were collected using a force plate, and the data were used to train a neural network controller of a model of sitting posture. The trained networks were then probed for sensitivity to position, velocity, and acceleration information at various time delays. Infants with typical development developed a higher reliance on velocity information in control in the anterior-posterior axis, and used more types of information in control in the …

The Influence Of Visual Perception Of Self-Motion On Locomotor Adaptation To Unilateral Limb Loading, Mukul Mukherjee, K.-C. Siu, Dimitrios Kastavelis, Pierre B. Fayad, Nikolaos Stergiou

Journal Articles

Self-perception of motion through visual stimulation may be important for adapting to locomotor conditions. Unilateral limb loading is a locomotor condition that can improve stability and reduce abnormal limb movement. In the present study, the authors investigated the effect of self-perception of motion through virtual reality (VR) on adaptation to unilateral limb loading. Healthy young adults, assigned to either a VR or a non-VR group, walked on a treadmill in the following 3 locomotor task periods—no load, loaded, and load removed. Subjects in the VR group viewed a virtual corridor during treadmill walking. Exposure to VR reduced cadence and muscle …

Approximate Entropy Used To Assess Sitting Postural Sway Of Infants With Developmental Delay, Joan E. Deffeyes, Regina T. Harbourne, Wayne A. Stuberg, Nikolaos Stergiou

Journal Articles

Infant sitting postural sway provides a window into motor development at an early age. The approximate entropy, a measure of randomness, in the postural sway was used to assess developmental delay, as occurs in cerebral palsy. Parameters used for the calculation of approximate entropy were investigated, and approximate entropy of postural sway in early sitting was found to be lower for infants with developmental delay in the anterior–posterior axis, but not in the medial–lateral axis. Spectral analysis showed higher frequency features in the postural sway of early sitting of infants with typical development, suggesting a faster control mechanism is active …

Velocity At Lactate Threshold And Running Economy Must Also Be Considered Along With Maximal Oxygen Uptake When Testing Elite Soccer Players During Preseason, Giorgos Ziogas, Kostas Patras, Nikolaos Stergiou, Anastasios D. Georgoulis

Journal Articles

Velocity at lactate threshold and running economy must also be considered along with maximal oxygen uptake when testing elite soccer players during preseason. J Strength Cond Res 25(2): 414-419, 2011-Maximal oxygen uptake (V̇o₂max) has been traditionally used to explain physiologic differences among soccer teams of different ranking. However, other endurance markers may have greater discriminatory ability. The purpose of this study was to examine whether velocity at lactate threshold and running economy can be used to better discriminate endurance characteristics of soccer teams of different levels along with V̇o₂max during preseason testing. One hundred twenty-nine professional …

Multiple Sclerosis Affects The Frequency Content In The Vertical Ground Reaction Forces During Walking, Shane R. Wurdeman, Jessie M. Huisinga, Mary Filipi, Nikolaos Stergiou

Journal Articles

Background: Multiple sclerosis is a progressive neurological disease that results in a high incident of gait disturbance. Exploring the frequency content of the ground reaction forces generated during walking may provide additional insights to gait in patients with multiple sclerosis that could lead to specific tools for differential diagnosis. The purpose of this study was to investigate differences in the frequency content of these forces in an effort to contribute to improved clinical management of this disease.

Methods: Eighteen patients and eighteen healthy controls walked across a 10 meter long walkway. The anterior–posterior and vertical ground reaction forces generated …

Walking Abnormalities Are Associated With Copd: An Investigation Of The Nhanes Iii Dataset, Jenna M. Yentes, Harlan Sayles, Jane Meza, David M. Mannino, Stephen I. Rennard, Nikolaos Stergiou

Journal Articles

Research on the peripheral effects of COPD has focused on physiological and structural changes. However, different from muscular weakness or decreased physical activity, mechanical abnormalities of the muscular system, e.g. walking, have yet to be investigated. Our purpose was to utilize the National Health and Nutritional Examination Survey (NHANES) dataset to determine whether walking abnormalities are associated with COPD severity. To determine if walking abnormalities were independently associated with COPD severity, our analysis aimed to investigate the association of physical activity levels with COPD severity and with walking abnormalities. The NHANES III dataset that contains data for 31,000 persons that …

Elliptical Exercise Improves Fatigue Ratings And Quality Of Life In Patients With Multiple Sclerosis, Jessie M. Huisinga, Mary Filipi, Nikolaos Stergiou

Journal Articles

Fatigue, reduced quality of life (QOL), and lower physical activity levels are commonly reported in patients with multiple sclerosis (MS). This study evaluated the effects of elliptical exercise on fatigue and QOL reports in patients with MS. Patients with MS (n = 26) completed the Fatigue Severity Scale (FSS), the Modified Fatigue Impact Scale (MFIS), and the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) before and after completing 15 elliptical exercise training sessions. Changes in fatigue and QOL were assessed based on any changes in the fatigue and SF-36 questionnaires, and correlations between changes in each of the …

Anterior-Posterior And Medial-Lateral Control Of Sway In Infants During Sitting Acquisition Does Not Become Adult-Like, Fabien Cignetti, Anastasia Kyvelidou, Regina T. Harbourne, Nikolaos Stergiou

Journal Articles

We examined (1) how sitting postural control in infants develops in the anterior–posterior (A/P) and medial–lateral (M/L) directions of sway, and (2) whether this control is already adult-like during the late phase of infant's sitting acquisition. COP data were acquired from 14 healthy infants (from the onset of sitting until independent sitting) and 21 healthy adults while sitting on a force platform. Attractor dimensionality (CoD: correlation dimension), attractor predictability (LyE: largest Lyapunov exponent), and sway variability (RMS: root-mean square) were calculated from the COP data to evaluate postural control. In the A/P direction, sitting was mastered by the infants by …

Electromechanical Delay Of The Knee Flexor Muscles After Harvesting The Hamstrings For Anterior Cruciate Ligament Reconstruction, Stavros Ristanis, Elias Tsepis, Dimitrios Giotis, Franceska Zampeli, Nikolaos Stergiou, Anastasios D. Georgoulis

Journal Articles

Objective: To investigate if harvesting of semitendinosus (ST) and gracilis for anterior cruciate ligament (ACL) reconstruction will have an effect in coordinative firing pattern of the hamstrings under fatigue. We hypothesized that fatigue will increase the electromechanical delay (EMD) of the hamstrings on the harvested site and impair the synchronization between the medial and lateral hamstrings, in terms of muscle activity onsets.

Design: Prospective nonrandomized study. Setting: Institutional. Patients: Twelve ACL reconstructed patients with hamstrings, 2 years postoperatively.

Interventions: The patients performed a fatigue protocol with 25 continuous maximal isometric voluntary contractions of 8-second duration with 2-second …

Stride-To-Stride Variability Is Altered During Backward Walking In Anterior Cruciate Ligament Deficient Patients, Franceska Zampeli, Constantina Moraiti Moraiti, Sofia Xergia, Vasilios Tsiaras, Nikolaos Stergiou, Anastasios D. Georgoulis

Journal Articles

Background: Recently backward walking is used by physical therapists to strengthen the hamstring muscles and thus improve the function of the knee joint of anterior cruciate ligament deficient patients. The aim of this study was to examine the stride-to-stride variability of anterior cruciate ligament deficient patients during backward walking. The variation of how a motor behavior emerges in time is best captured by tools derived from nonlinear dynamics, for which the temporal sequence in a series of values is the facet of interest.

Methods: Fifteen patients with unilateral anterior cruciate ligament deficiency and eleven healthy controls walked backwards …

The Effect Of Music On Robot-Assisted Laparoscopic Surgical Performance, Ka-Chun Siu, I. H. Suh, Mukul Mukherjee, D. Oleynikov, Nikolaos Stergiou

Journal Articles

Music is often played in the operating room to increase the surgeon’s concentration and to mask noise. It could have a beneficial effect on surgical performance. Ten participants with limited experience with the da Vinci robotic surgical system were recruited to perform two surgical tasks: suture tying and mesh alignment when classical, jazz, hip-hop, and Jamaican music were presented. Kinematics of the instrument tips of the surgical robot and surface electromyography of the subjects were recorded. Results revealed that a significant music effect was found for both tasks with decreased time to task completion (P = .005) and total …

A Comparison Of Interventions For Children With Cerebral Palsy To Improve Sitting Postural Control: A Clinical Trial, Regina T. Harbourne, Sandra L. Willett, Anastasia Kyvelidou, Joan E. Deffeyes, Nikolaos Stergiou

Journal Articles

Background The ability to sit independently is fundamental for function but delayed in infants with cerebral palsy (CP). Studies of interventions directed specifically toward sitting in infants with CP have not been reported.

Objective The purpose of this study was to compare 2 interventions for improving sitting postural control in infants with CP.

Design For this randomized longitudinal study, infants under 2 years of age and at risk for CP were recruited for intervention directed toward sitting independence.

Setting The intervention was conducted at home or at an outpatient facility.

Patients and Intervention Fifteen infants with typical development (mean age …