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Articles 1 - 21 of 21
Full-Text Articles in Life Sciences
Chapter 9: Biomechanics, Nicholas Stergiou, Daniel Blanke, Sara A. Myers, Ka-Chun Siu
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 …
The Rim And The Ancient Mariner: The Nautical Horizon Affects Postural Sway In Older Adults, Justin Munafo, Michael G. Wade, Nick Stergiou, Thomas A. Stoffregen
The Rim And The Ancient Mariner: The Nautical Horizon Affects Postural Sway In Older Adults, Justin Munafo, Michael G. Wade, Nick Stergiou, Thomas A. Stoffregen
Journal Articles
On land, the spatial magnitude of postural sway (i.e., the amount of sway) tends to be greater when participants look at the horizon than when they look at nearby targets. By contrast, on ships at sea, the spatial magnitude of postural sway in young adults has been greater when looking at nearby targets and less when looking at the horizon. Healthy aging is associated with changes in the movement patterns of the standing body sway, and these changes typically are interpreted in terms of age-related declines in the ability to control posture. To further elucidate the mechanisms associated with these …
Indifference To Chaotic Motion May Be Related To Social Disinterest In Children With Autism, Joshua L. Haworth, Anastasia Kyvelidou, Wayne Fisher, Nicholas Stergiou
Indifference To Chaotic Motion May Be Related To Social Disinterest In Children With Autism, Joshua L. Haworth, Anastasia Kyvelidou, Wayne Fisher, Nicholas Stergiou
Journal Articles
Children with autism spectrum disorder tend to have little interest in the presence, actions, and motives of other persons. In addition, these children tend to present with a limited and overly redundant movement repertoire, often expressing hyperfixation and aversion to novelty. We explore whether this is related to a more fundamental lack of appreciation for various temporal dynamics, including periodic, chaotic, and aperiodic motion structures. Seven children with ASD (age, gender, and height matched with children without ASD) were asked to stand and watch the motion of a visual stimulus displayed on a large (55") video monitor. Gaze and posture …
Dynamic Perception Of Dynamic Affordances: Walking On A Ship At Sea, Hannah Walter, Jeffrey B. Wagman, Nicholas Stergiou, Nurtekin Erkmen, Thomas A. Stoffregen
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
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 …
Speed And Rhythm Affect Temporal Structure Of Variability In Reaching Poststroke: A Pilot Study, Amit Sethi, Nicholas Stergiou, Tara Patterson, Carolynn Patten, Lorie G. Richards
Speed And Rhythm Affect Temporal Structure Of Variability In Reaching Poststroke: A Pilot Study, Amit Sethi, Nicholas Stergiou, Tara Patterson, Carolynn Patten, Lorie G. Richards
Journal Articles
Temporal structure reveals the potential adaptive strategies employed during upper extremity movements. The authors compared the temporal structure of upper extremity joints under 3 different reaching conditions: preferred speed, fast speed, and reaching with rhythmic auditory cues in 10 individuals poststroke. They also investigated the temporal structure of these 3 reaching conditions in 8 healthy controls to aid in the interpretation of the observed patterns in the poststroke cohort. Approximate entropy (ApEn) was used to measure the temporal structure of the upper extremity joints. ApEn was similar between conditions in controls. After stroke, ApEn was significantly higher for shoulder, elbow, …
Effect Of Timing Of Hip Extension Assistance During Loaded Walking With A Soft Exosuit, Ye Ding, Fausto A. Panizzolo, Christopher Siviy, Philippe Malcolm, Ignacio Galiana, Kenneth G. Holt, Conor J. Walsh
Effect Of Timing Of Hip Extension Assistance During Loaded Walking With A Soft Exosuit, Ye Ding, Fausto A. Panizzolo, Christopher Siviy, Philippe Malcolm, Ignacio Galiana, Kenneth G. Holt, Conor J. Walsh
Journal Articles
Background
Recent advances in wearable robotic devices have demonstrated the ability to reduce the metabolic cost of walking by assisting the ankle joint. To achieve greater gains in the future it will be important to determine optimal actuation parameters and explore the effect of assisting other joints. The aim of the present work is to investigate how the timing of hip extension assistance affects the positive mechanical power delivered by an exosuit and its effect on biological joint power and metabolic cost during loaded walking. In this study, we evaluated 4 different hip assistive profiles with different actuation timings: early-start-early-peak …
The Effect Of Skinfold On The Assessment Of The Mean Power Frequency At The Fatigue Threshold, Alyssandra N. Baniqued, Jorge M. Zuniga, Thomas C. Strunc, Katie M. Keenan, Agrini K. Boken, Jeffrey J. Anderson
The Effect Of Skinfold On The Assessment Of The Mean Power Frequency At The Fatigue Threshold, Alyssandra N. Baniqued, Jorge M. Zuniga, Thomas C. Strunc, Katie M. Keenan, Agrini K. Boken, Jeffrey J. Anderson
Journal Articles
The purpose of this study was to determine if the amount of subcutaneous tissue over the quadriceps affects the assessment of mean power frequency at the fatigue threshold (MPFFT). It was hypothesized that greater skinfold values will result in lower power outputs associated to the MPFFT. Fourteen adults (Mean ± SD age = 20.7 ± 0.99; body weight = 72.8 ± 12.6 kg) performed an incremental cycle ergometry test to exhaustion while surface electromyographic (EMG) signals were measured from the vastus lateralis. The skinfold thickness of each leg was taken prior to the test, and skinfold thicknesses were separated into …
Effects Of Aging On The Relationship Between Cognitive Demand And Step Variability During Dual-Task Walking, Leslie M. Decker, Fabien Cignetti, Nathaniel Hunt, Jane F. Potter, Nicholas Stergiou, Stephanie A. Studenski
Effects Of Aging On The Relationship Between Cognitive Demand And Step Variability During Dual-Task Walking, Leslie M. Decker, Fabien Cignetti, Nathaniel Hunt, Jane F. Potter, Nicholas Stergiou, Stephanie A. Studenski
Journal Articles
A U-shaped relationship between cognitive demand and gait control may exist in dual-task situations, reflecting opposing effects of external focus of attention and attentional resource competition. The purpose of the study was twofold: to examine whether gait control, as evaluated from step-to-step variability, is related to cognitive task difficulty in a U-shaped manner and to determine whether age modifies this relationship. Young and older adults walked on a treadmill without attentional requirement and while performing a dichotic listening task under three attention conditions: non-forced (NF), forced-right (FR), and forced-left (FL). The conditions increased in their attentional demand and requirement for …
Adding Stiffness To The Foot Modulates Soleus Force-Velocity Behaviour During Human Walking, Kota Z. Takahashi, Michael T. Gross, Herman Van Werkhoven, Stephen J. Piazza, Gregory S. Sawicki
Adding Stiffness To The Foot Modulates Soleus Force-Velocity Behaviour During Human Walking, Kota Z. Takahashi, Michael T. Gross, Herman Van Werkhoven, Stephen J. Piazza, Gregory S. Sawicki
Journal Articles
Previous studies of human locomotion indicate that foot and ankle structures can interact in complex ways. The structure of the foot defines the input and output lever arms that influences the force-generating capacity of the ankle plantar flexors during push-off. At the same time, deformation of the foot may dissipate some of the mechanical energy generated by the plantar flexors during push-off. We investigated this foot-ankle interplay during walking by adding stiffness to the foot through shoes and insoles, and characterized the resulting changes in in vivo soleus muscle-tendon mechanics using ultrasonography. Added stiffness decreased energy dissipation at the foot …
Aging Affects Postural Tracking Of Complex Visual Motion Cues, Haralampos Sotirakis, Anastasia Kyvelidou, L. Mademli, Nicholas Stergiou, Vassilia Hatzitaki
Aging Affects Postural Tracking Of Complex Visual Motion Cues, Haralampos Sotirakis, Anastasia Kyvelidou, L. Mademli, Nicholas Stergiou, Vassilia Hatzitaki
Journal Articles
Postural tracking of visual motion cues improves perception–action coupling in aging, yet the nature of the visual cues to be tracked is critical for the efficacy of such a paradigm. We investigated how well healthy older (72.45 ± 4.72 years) and young (22.98 ± 2.9 years) adults can follow with their gaze and posture horizontally moving visual target cues of different degree of complexity. Participants tracked continuously for 120 s the motion of a visual target (dot) that oscillated in three different patterns: a simple periodic (simulated by a sine), a more complex (simulated by the Lorenz attractor that is …
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
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 …
Associations Between Mobility, Cognition And Callosal Integrity In People With Parkinsonism, Brett W. Fling, Marian L. Dale, Carolin Curtze, Katrijn Smulders, John G. Nutt, Fay B. Horak
Associations Between Mobility, Cognition And Callosal Integrity In People With Parkinsonism, Brett W. Fling, Marian L. Dale, Carolin Curtze, Katrijn Smulders, John G. Nutt, Fay B. Horak
Journal Articles
Falls in people with parkinsonism are likely related to both motor and cognitive impairments. In addition to idiopathic Parkinson's disease (PD), some older adults have lower body parkinsonism (a frontal gait disorder), characterized by impaired lower extremity balance and gait as well as cognition, but without tremor or rigidity. Neuroimaging during virtual gait suggests that interhemispheric, prefrontal cortex communication may be involved in locomotion, but contributions of neuroanatomy connecting these regions to objective measures of gait in people with parkinsonism remains unknown. Our objectives were to compare the integrity of fiber tracts connecting prefrontal and sensorimotor cortical regions …
Mastoid Vibration Affects Dynamic Postural Control During Gait, Jung Chien, Mukul Mukherjee, Nicholas Stergiou
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 …
Chapter 5: Surrogation, Sara A. Myers
Chapter 5: Surrogation, Sara A. Myers
Journal Articles
One of the goals of time series analysis is to understand the underlying mechanisms that generate different dynamics for different time series. If a time series is not a product of random process, then we can assume that some kind of dynamics govern the time series. The question is what kinds of dynamics are controlling the time series. For nonlinear time series analysis, our focus is on nonlinear dynamics, and one of the goals is to characterize those dynamics by applying nonlinear tools. However, it is important to establish evidence of nonlinearity in a time series first in order to …
Chapter 8: Autocorrelation Function, Mutual Information, And Correlation Dimension, Nathaniel Hunt
Chapter 8: Autocorrelation Function, Mutual Information, And Correlation Dimension, Nathaniel Hunt
Journal Articles
In this chapter, we will discuss in greater detail the autocorrelation function and the mutual information we mentioned in Chapter 3 on the reconstruction of the state space. We will also cover a new measure called the correlation dimension, which quantifies the dimensionality of an attractor.
Chapter 2: Time Series, Sara A. Myers
Chapter 2: Time Series, Sara A. Myers
Journal Articles
Time series is “simply a list of numbers assumed to measure some process sequentially in time” (Stergiou et al. 2004). Mathematicians have a more formal definition, that is, a set or a sequence of observations, with each one recorded at specific times, or at least sequentially (Brockwell and Davis 2002; Box et al. 2008). Time series are created from multiple sources for research purposes to understand various behaviors. For example, social scientists could collect graduation rates, physiologists record heart rates, economists study consumer spending, and climatologists examine weather patterns. Basically, any time observations are taken repeatedly over time, from any …
The Effect Of Cardiorespiratory Fitness On The Assessment Of The Physical Working Capacity At The Fatigue Threshold, Brittney M. Mikkelsen, Jorge Zuniga, William K. Herron, Frances E. Frauso, Anne N. Pulliam
The Effect Of Cardiorespiratory Fitness On The Assessment Of The Physical Working Capacity At The Fatigue Threshold, Brittney M. Mikkelsen, Jorge Zuniga, William K. Herron, Frances E. Frauso, Anne N. Pulliam
Journal Articles
Purpose: The purpose of this study was to determine if different cardiorespiratory fitness levels (maximal oxygen uptake or VO2max) affect neuromuscular fatigue as measured by the physical working capacity at the fatigue threshold (PWCFT). Methods: Fourteen adults (14 men; mean ± SD; age = 20.79 ± 0.89 years; body weight = 80.7 ± 10.91 kg; height = 178.4 ± 5.29 cm) volunteered to participate in the investigation. Each participant performed an incremental cycle ergometry test to fatigue while electromyographic (EMG) signals were measured from the vastus lateralis (VL) muscle. Mean, standard deviation, and range values were calculated for …
Quantifying Muscle Fatigue Of The Low Back During Repetitive Load Lifting Using Lyapunov Analysis, Elias Spyropoulos, Anastasia Kyvelidou, Nicholas Stergiou, George Athanassiou
Quantifying Muscle Fatigue Of The Low Back During Repetitive Load Lifting Using Lyapunov Analysis, Elias Spyropoulos, Anastasia Kyvelidou, Nicholas Stergiou, George Athanassiou
Journal Articles
Background: Occupational low back disorders are often associated with exposure to work-related physical risk factors such as muscle fatigue in the low back.
Objective: The objective of this study was to investigate the possible relationship between the divergence of the kinematic trajectories of the low back system and the different stages of fatigue during the execution of a repetitive lifting task.
Methods: The patterns of the low back system were recorded using markers on specific vertebras during the repetitive load lifting from the floor to a 0.75 m height table. The maximum Lyapunov exponent, λmax of the recorded patterns was …
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
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 …65>
Freezing Of Gait Associated With A Corpus Callosum Lesion, Marian L. Dale, Martina Mancini, Carolin Curtze, Fay B. Horak, Brett W. Fling
Freezing Of Gait Associated With A Corpus Callosum Lesion, Marian L. Dale, Martina Mancini, Carolin Curtze, Fay B. Horak, Brett W. Fling
Journal Articles
Freezing of gait (FoG) is a debilitating feature of Parkinson’s disease and other parkinsonian disorders. This case demonstrates a variant of freezing of gait in a non-parkinsonian patient with a lesion of the anterior corpus callosum. The freezing improved with increased upper extremity sensory input, suggesting that compensatory circuits for use of somatosensory inputs from the arms to postural and locomotor centers were intact.