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Baroni G - - 2001
The functional approach to studying human motor systems attempts to give a better understanding of the processes behind planning movements and their coordinated performance by relying on weightlessness as a particularly enlightening experimental condition. Indeed, quantitative monitoring of sensorimotor adaptation of subjects exposed to weightlessness outlines the functional role of ...
Bussmann J B - - 2001
Advanced ambulatory systems that measure aspects of overt human behavior during normal daily life have become feasible, owing to developments in data recording and sensor technology. One such instrument is the Activity Monitor (AM). This paper provides a technical description of the AM and information about its validity and current ...
Kee D - - 2001
This paper presents a technique for postural loading on the upper body assessment (LUBA). The proposed method is based on the new experimental data for composite index of perceived discomfort (ratio values) for a set of joint motions, including the hand, arm, neck and back, and the corresponding maximum holding ...
Buchanan J J JJ Texas A&M University, Department of Health and Kinesiology, College Station 77843-4243, USA. - - 2001
In this study, we examined flexibility in postural coordination by inducing transitions between postural patterns. Previous work demonstrated that the postural control system produces two task-specific postural patterns as a function of the frequency of support surface translation. For slow translation frequencies (<0.5 Hz), subjects ride on the platform reminiscent ...
Darlington C L - - 2001
We investigated the effects of the menstrual cycle on visual-vestibular interaction by measuring optokinetic function and postural stability at different phases of the cycle. Menstrual cycle phase had no significant effect on gaze-holding, optokinetic nystagmus slow phase velocity, amplitude or frequency, circularvection latency or optokinetic afternystagmus frequency, amplitude or duration. ...
Hertel J - - 2001
OBJECTIVE: To investigate the effects of different rearfoot orthotics on postural sway during unilateral stance after lateral ankle sprain. DESIGN: Repeated-measures 3-factor analysis of variance on postural sway length and velocity in the frontal and sagittal planes with factors being stance leg (injured, uninjured), session (within 3 d, 2 wk, ...
Conforto S - - 2001
The postural control system is assessed by observing body sway while the subject involved aims at maintaining a specified up-right posture. Internal masses generate internal reaction forces that constitute an internal mechanical stimulus that may contribute to cause segmental displacements, i.e. body sway. Thus, gaining knowledge about the amplitude and ...
Katzir G G Department of Biology, University of Haifa at Oranim. - - 2001
We examined head stabilization in relation to body mass and length of legs in four heron species (little egrets, Egretta garzetta; night herons, Nycticorax nycticorax; squacco herons, Ardeola ralloides; and cattle egrets, Bubulcus ibis: Aves: Ardeidae). Head stabilization, under controlled, sinusoidal, perch perturbations was mostly elicited at frequencies lower than ...
Aissaoui R - - 2001
This study was undertaken to investigate the effect of system tilt and back recline angles on sliding and pressure distribution of seated subjects. Ten able-bodied subjects adopted successively 12 postures on a multiadjustable simulator chair. The system tilt angle was varied from 0 degrees to 45 degrees posterior tilt, while ...
States R A - - 2001
In this study, the authors examined the interplay between biomechanics and control strategies in the resolution of excess degrees of freedom at the joint level. Seven participants made aimed arm movements from 30 starting points and several starting postures to targets. Final arm postures for movements to a target exhibited ...
Scinicariello A P - - 2001
With galvanic vestibular stimulation (GVS), electrical current is delivered transcutaneously to the vestibular afferents through electrodes placed over the mastoid bones. This serves to modulate the continuous firing levels of the vestibular afferents, and causes a standing subject to lean in different directions depending on the polarity of the current. ...
Fukuoka Y - - 2001
In the present study, the function of the somatosensory feedback system in postural control was investigated. For the sake of simplicity, the present study considered only balancing in the anteroposterior direction using the ankle strategy, in which the ankle moment is mainly used to maintain balance. To suppress the vestibular ...
Rogers M W - - 2001
OBJECTIVES: To investigate the influence of different reaction stimulus cues on the characteristics of ground reaction forces during the initiation of rapid forward stepping, and to determine whether age-related differences in step initiation are influenced by the type of stimulus cue used to trigger stepping. DESIGN: Case-control study. SETTING: University-based ...
Loram I D - - 2001
Using the ankle musculature, subjects balanced a large inverted pendulum. The equilibrium of the pendulum is unstable and quasi-regular sway was observed like that in quiet standing. Two main questions were addressed. Can subjects systematically change sway size in response to instruction and availability of visual feedback? If so, do ...
Carpenter M G MG Neural Control Laboratory, University of Waterloo, Waterloo, Ontario, - - 2001
In order to utilize static posturography as a tool with which to diagnose pathological balance disorders, it is necessary to understand the contribution of psychological factors such as fear of falling. In this study we examined kinetic and kinematic parameters during quiet stance of eight young healthy adults standing under ...
Guerraz M M MRC Human Movement and Balance Unit, Institute of Neurology, 8-11 Queen Square, WC1N 3BG, London, - - 2001
Previous studies have shown that human subjects presented with a moving visual environment initiate a postural re-adjustment in the direction of motion. The present study investigated how active control or expectation of the displacement of a visual scene affects this postural response. Center of foot pressure (COP) and head displacement ...
Kaufman G D GD Life Sciences Research Laboratories, Mail Code SD-3, NASA/Johnson Space Center, Houston, TX 77058-3696, - - 2001
To better understand the mechanisms of human adaptation to rotating environments, we exposed 19 healthy subjects and 8 vestibular-deficient subjects ("abnormal"; four bilateral and four unilateral lesions) to an interaural centripetal acceleration of 1 g (resultant 45 degrees roll-tilt of 1.4 g) on a 0.8-m-radius centrifuge for periods of 90 ...
Albani G - - 2001
Many instruments have been employed in recent years in order to quantify the posture and motion of the head in normal and pathological subjects. Evaluations of this type present many difficulties related to the influence of individual and external factors and to the accuracy of the system used. In patients ...
Loughlin P J - - 2001
Spectral analysis and time-frequency analysis were applied to anterior-posterior (A-P) center-of-pressure (COP) data collected during quiet stance and sinusoidal (0.25 Hz) moving visual scene perturbations from sixteen healthy elderly subjects and thirteen healthy young subjects. While the total energy of COP was larger in the elderly subjects than in the ...
Layne C S - - 2001
This report is the first systematic evaluation of the effects of prolonged weightlessness on the bipedal postural control processes during self-generated perturbations produced by voluntary upper limb movements. Spaceflight impacts humans in a variety of ways, one of which is compromised postflight postural control. We examined the neuromuscular activation characteristics ...
Krebs D E - - 2001
People with cerebellar ataxia lack lower limb coordination and dissipate sway motion slowly and inefficiently after a posture perturbation. We report a practical and low-cost "human resonance frequency test" for both laboratory and clinical use to quantify progress in balance and cerebellar rehabilitation. We assumed that the center-of-pressure (COP) oscillation ...
Rogers M W MW Prince of Wales Medical Research Institute, Sydney, NSW, - - 2001
The effects of passive tactile cues about body sway on stability during standing were evaluated in subjects with a wide range of sensorimotor and balance performance. Healthy young adults, diabetic subjects with varying degrees of peripheral sensory neuropathy and older subjects aged 70-80 years were studied. Body sway was measured ...
Matjacić Z - - 2001
The objective of this study was to assess functional postural responses by analyzing the net joint torques (NJT) in the ankles and the hips resulting from perturbations delivered in multiple directions to subjects standing quietly. A total of eight subjects were standing on two force platforms while an apparatus randomly ...
Bothner K E - - 2001
The common platform translation paradigm used in balance control studies employs a disturbance event that applies non-muscular forces to the body for the duration of the disturbance. Previous research has explored the process of constructing the balance recovery by considering these perturbations to be trigger events, not events with an ...
Baroni G - - 2001
The adaptation of dynamic movement-posture coordination during forward trunk bending was investigated in long-term weightlessness. Three-dimensional movement analysis was carried out in two astronauts during a 4-mo microgravity exposure. The principal component analysis was applied to joint-angle kinematics for the assessment of angular synergies. The anteroposterior center of mass (CM) ...
Guerraz M M Medical Research Council, National Hospital for Neurology and Neurosurgery, London, England. - - 2001
Unidirectional motion of a uniplanar background induces a codirectional postural sway. It has been shown recently that fixation of a stationary foreground object induces a sway response in the opposite direction (Bronstein & Buckwell, 1997) when the background moves transiently. The present study investigated factors determining this contradirectional postural response. ...
Pagnacco G - - 2001
There is no consensus as to the origins of the oscillations of the vertical ground reaction force during quiet stance. The concept of a cardiovascular origin is supported by many ballistocardiographic studies, but its exclusivity has never been proven. A new hypothesis was formulated to explain their genesis: there is ...
Lopez-Lopez J A - - 2001
BACKGROUND: Discomfort in the lumbar region is a frequent complaint of helicopter pilots. Two factors that helicopter crewmembers relate to back pain are exposure to vibration and poor posture during flight, because during flight the seat and controls force the pilot to adopt an asymmetric posture. Repeated exposure to these ...
Rougier P - - 2000
The authors modeled the center of gravity vertical projection (CG(v)) and the difference, CP - CG(v), which, combined, constitute the center of pressure (CP) trajectory, as fractional Brownian motion in order to investigate their relative contributions and their spatiotemporal articulation. The results demonstrated that CG(v) and CP - CG(v) motions ...
Karnath H O - - 2000
BACKGROUND: Stroke patients may exhibit the peculiar behavior of actively pushing away from the nonhemiparetic side, leading to lateral postural imbalance and a tendency to fall toward the paralyzed side. This phenomenon has been called the "pusher syndrome." OBJECTIVE: The current study analyzes the mechanism leading to contraversive pushing. METHODS: ...
Golomer E - - 2000
In subjects of both sexes with or without dance training, dependence on vision and proprioception for postural control was studied by destabilizing these cues on a free seesaw. Fast Fourier transform processing allowed spectral frequency analysis of the platform sways recorded by an accelerometer. Two frequency bands of the total ...
Chaudhuri S - - 2000
OBJECTIVE: To determine the effect of lifts to the shoe of the nonaffected leg on weight symmetry and dynamic posturography in individuals with hemiparesis. DESIGN: Quantitative posturography was performed to determine subjects' response to sudden perturbations. Subjects received graded forward and backward perturbations while standing on a movable force platform. ...
Patton J L JL Rehabilitation Institute of Chicago, Department of Biomedical Engineering, Northwestern University, IL 60611, USA. - - 2000
This study tested the hypothesis that subjects improve their relative stability as they learn a dynamic pulling task. Healthy adult subjects practiced making brief horizontal pulls (<300 ms) on a handle to a range of target forces ranging from 20 to 80% of their estimated maximum for 5 days. They ...
Guerraz M - - 2000
PURPOSE: To investigate how humans with congenital nystagmus (CN) use visual information to stabilize and orient their bodies in space. METHODS: Center of foot pressure (COP) and head displacements in the lateral plane were recorded using a sway platform and Schottky barrier photodetector, respectively. In experiment 1, a comparison was ...
Popovic M - - 2000
A new stability criterion that can be used to assess the standing condition of a subject from center of pressure (CoP) measurements is presented. This criterion can be applied, for example, to control a standing prosthesis, which should allow a paraplegic subject to stand up, sit down and stand safely ...
Gantchev N - - 2000
The primary purpose of this paper was to compare the effect of reversing the direction of step initiation in Parkinson's disease. Forward (FDS) and backward (BDS) oriented stepping initiation analyses were conducted on combined kinematic and kinetic data recorded on Parkinsonian patients (PD) and healthy age-matched subjects. Two successive phases ...
Talis V L - - 2000
We investigated the development of postural reactions induced in standing subjects by Achilles tendon vibration. We compared vibratory reactions in 3 different conditions: normal standing, standing near support, and when the solid support being protracted forward changed the initial posture. Additional support for the back was placed at subject's sacral ...
Fransson P - - 2000
New methods were developed to determine the dynamic changes of postural control during the initial exposure to large perturbances of stance. The adjustments of postural control over time in measured anteroposterior torque, were investigated in ten normal subjects. Perturbations of stance were evoked by two high intensity vibrators applying pseudorandom ...
Jeka J J Department of Kinesiology, University of Maryland, College Park 20742-2611, - - 2000
Despite extensive research on the influence of visual, vestibular and somatosensory information on human postural control, it remains unclear how these sensory channels are fused for self-orientation. The focus of the present study was to test whether a linear additive model could account for the fusion of touch and vision ...
Foerster F - - 2000
Basic motion patterns and posture can be distinguished by multichannel accelerometry, as recently shown. A refinement of this method appeared to be desirable to further increase its effectiveness, especially to distinguish walking and climbing stairs, and body rotation during sleep. Recordings were made of 31 subjects, according to a standard ...
Fenety P A - - 2000
Sitting discomfort is traditionally evaluated with subjective rating scales which are referenced to an objective correlate (e.g. sitting posture) measured on a static (i.e. non-continuous) basis. Since sitting discomfort is dynamic in nature, it requires continuous, objective measurement. We therefore adapted an interface pressure mat to continuously record in-chair movement ...
Rougier P - - 2000
In order to evaluate the long term effect of blindness on an undisturbed postural task, seven blind individuals (BLI) were compared to twelve healthy individuals (REF) who were required to close their eyes. To this aim, centre of pressure (CP) trajectories were recorded through a force platform on which the ...
Rowland WJ - - 2000
I examined biased patterns of habituation that occur when reproductive male three-spined stickleback, Gasterosteus aculeatus, respond to a choice of two dummy females, one displaying the head-up posture of a sexually receptive female and an otherwise identical dummy lacking this sign stimulus (i.e. a dummy in a 'neutral' horizontal posture). ...
Kawakita T - - 2000
PURPOSE: A significant correlation between the magnitude of linear vection and the degree of body sway induced by a visual stimulus perceived as moving in depth was previously described (Jpn J Physiol 49: 417-424, 1999). The purpose of this study was to examine the role of the central and peripheral ...
Akiyama N - - 2000
We confirmed a diaphragmatic motion during mechanical ventilation in four patients with central nervous system damage. The right hemidiaphragm were visualized with 3.5 MHz ultrasound, and motion was measured using time-motion analysis in separate postures. The dome was most impaired during the right decubitus posture. The crural region was most ...
Hudson C C CC Biomotion Laboratory, Massachusetts General Hospital, Boston, - - 2000
Objective attempts to characterize postural control in subjects with cerebellar (Cb) pathology have focused primarily on sagittal plane responses to static standing, semi-dynamic standing, and platform perturbation. Repeated, dynamic, functional movement may provide a better opportunity to study the effects of ataxia on frontal plane postural stability. The purpose of ...
Bouisset S S Laboratoire de Physiologie du Mouvement, Université Paris-Sud, Orsay, - - 2000
Dynamic phenomena, termed anticipatory postural adjustments (APA), are known to precede the onset of voluntary movement. Their anticipatory nature confers a particular status on APAs: as they cannot be triggered reflexly by afferent signals induced by a voluntary movement, it can be asked whether the APA parameters are centrally programmed ...
Hodges P W - - 2000
Three-dimensional trunk motion, trunk muscle electromyography and intra-abdominal pressure were evaluated to investigate the preparatory control of the trunk associated with voluntary unilateral upper limb movement. The directions of angular motion produced by moments reactive to limb movement in each direction were predicted using a three-dimensional model of the body. ...
Becker W W Sektion Neurophysiologie, Universität Ulm, Germany. - - 2000
We investigated whether posture - either seated (S) or upright standing (O, orthostatic) - affects the vestibular perceptions of angular velocity (V) and displacement (D) in the horizontal plane. We also examined whether the two perceptions are equivalent, that is, whether perceived displacement can be viewed as the time integral ...
Maurer C - - 2000
We investigated the changes of human posture control of upright stance which occur when vestibular cues (VEST) are absent and visual and somatosensory orientation cues (VIS, SOM) are removed. Postural responses to sinusoidal tilts of a motion platform in the sagittal plane (+/-2 degrees, f=0.05, 0.1, 0.2 and 0.4 Hz) ...
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