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postural sway muscle tone

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https://www.readbyqxmd.com/read/23623606/stiffness-control-of-balance-during-dual-task-and-prospective-falls-in-older-adults-the-mobilize-boston-study
#1
Hyun Gu Kang, Lien Quach, Wenjun Li, Lewis A Lipsitz
Outdoor fallers differ from indoor fallers substantially in demographics, lifestyle, health condition and physical function. Biomechanical predictors of outdoor falls have not been well characterized. Current validated measures of postural deficits, which describe only the overall postural behavior, are predictive of indoor falls but not outdoor falls. We hypothesized that a model-based description of postural muscle tone and reflexes, particularly during dual tasking, would predict outdoor falls. We tested whether postural stiffness and damping from an inverted pendulum model were predictive of future indoor and outdoor falls among older adults from the MOBILIZE Boston Study...
September 2013: Gait & Posture
https://www.readbyqxmd.com/read/22117463/-characteristics-of-postural-corrective-responses-before-and-after-long-term-spaceflight
#2
D G Saenko, A A Artamonov, I B Kozlovskaia
Balance function is dramatically deteriorated after exposure to microgravity. The purpose of the present study was to investigate the role and the contribution of different gravity sensory systems to the development of balance impairment after long-term spaceflights. Postural perturbations (pushes to the chest) of the threshold, medium, and sub-maximal intensities were produced in eight cosmonauts before, and on the day 3, 7, and 11 following spaceflight. Postural corrective responses were analyzed by anterior-posterior body sway fluctuation and electromyographic activity of leg muscles...
September 2011: Fiziologiia Cheloveka
https://www.readbyqxmd.com/read/21087656/haptic-touch-reduces-sway-by-increasing-axial-tone
#3
E Franzén, V S Gurfinkel, W G Wright, P J Cordo, F B Horak
It is unclear how haptic touch with a stable surface reduces postural sway. We hypothesized that haptic input enhances postural stability due to alterations in axial postural tone. We measured the influence of heavy and light touch (LT) of the hands on a stable bar on axial postural tone and postural sway during stance in 14 healthy adults. A unique "Twister" device measured hip torque by fixing the upper body in space while oscillating the surface in yaw ±10 at 1 deg/s. Subjects were tested while: (1) standing quietly with their arms at their sides, (2) lightly touching a rigid bar in front of them and (3) firmly gripping the bar...
February 3, 2011: Neuroscience
https://www.readbyqxmd.com/read/20844110/stiffness-control-of-balance-during-quiet-standing-and-dual-task-in-older-adults-the-mobilize-boston-study
#4
COMPARATIVE STUDY
Hyun Gu Kang, Lewis A Lipsitz
Distractions affect postural control, but this mechanism is not well understood. Diversion of resources during cognitive stress may lead to decreased motor drive and postural muscle tone. This may appear as decreased postural stiffness and increased postural sway amplitude. We hypothesized that dual tasking leads to decreased stiffness and increased sway amplitude. Postural sway (center of pressure; COP) data were used from 724 participants aged 77.9 ± 5.3 yr, a representative sample of community-dwelling older adults, the MOBILIZE Boston Study cohort...
December 2010: Journal of Neurophysiology
https://www.readbyqxmd.com/read/19506843/balance-control-under-different-passive-contributions-of-the-ankle-extensors-quiet-standing-on-inclined-surfaces
#5
Shun Sasagawa, Junichi Ushiyama, Kei Masani, Motoki Kouzaki, Hiroaki Kanehisa
Human bipedal stance is often modeled as a single inverted pendulum that pivots at the ankle joints in the sagittal plane. Because the center of body mass is usually maintained in front of the ankle joints, ankle extensor torque is continuously required to prevent the body from falling. During quiet standing, both passive and active mechanisms contribute to generate the ankle extensor torque counteracting gravity. This study aimed to investigate the active stabilization mechanism in more detail. Eight healthy subjects were requested to stand quietly on three different surfaces of 1) toes-up, 2) level, and 3) toes-down...
July 2009: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/17692315/axial-hypertonicity-in-parkinson-s-disease-direct-measurements-of-trunk-and-hip-torque
#6
W G Wright, V S Gurfinkel, J Nutt, F B Horak, P J Cordo
A cardinal feature of Parkinson's disease (PD) is muscle hypertonicity, i.e. rigidity. Little is known about the axial tone in PD or the relation of hypertonia to functional impairment. We quantified axial rigidity to assess its relation to motor symptoms as measured by UPDRS and determine whether rigidity is affected by levodopa treatment. Axial rigidity was measured in 12 PD and 14 age-matched controls by directly measuring torsional resistance of the longitudinal axis to twisting (+/-10 degrees ). Feet were rotated relative to fixed hips (Hip Tone) or feet and hips were rotated relative to fixed shoulders (Trunk Tone)...
November 2007: Experimental Neurology
https://www.readbyqxmd.com/read/17431597/stabilometric-signal-analysis-in-tests-with-sound-stimuli
#7
Míriam Raquel Meira Mainenti, Líliam Fernandes De Oliveira, Marco Antonio De Melo Tavares De Lima, Jurandir Nadal
Posture control is mediated by the integration between the environment information (coming from the visual, somatosensory and vestibular systems) and the efferent organs (motoneurons and muscles). The influence of the first systems on body sway signals is already documented in the literature. Few studies are focused in the relationship between stabilometric signals (objective measure of stability) and vestibular stimulation, due to the difficulty in achieving a specific and independent stimulation of this system...
August 2007: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/17196819/striatal-dopamine-denervation-and-sensory-integration-for-balance-in-middle-aged-and-older-adults
#8
Rakié Cham, Subashan Perera, Stephanie A Studenski, Nicolaas I Bohnen
UNLABELLED: The dopaminergic system of the basal ganglia has been implicated in the integration of sensory information important for balance based on studies in patients with Parkinson's disease. Striatal dopaminergic activity decreases with normal aging. OBJECTIVE: To investigate the relationship between regional striatal dopaminergic denervation and sensory information integration important for balance in middle-aged and older adults. METHODS: Community-dwelling subjects (N=35; age 41-83) with no clinical diagnoses of conditions affecting balance underwent dynamic posturography testing (Sensory Organization Test/SOT) and C-11-beta-CFT dopamine transporter positron emission tomography...
October 2007: Gait & Posture
https://www.readbyqxmd.com/read/16945974/craniocentric-body-sway-responses-to-500-hz-bone-conducted-tones-in-man
#9
Miriam S Welgampola, Brian L Day
Whole-body responses evoked by bone-conducted sound, a stimulus known to activate vestibular afferents, were recorded in standing subjects deprived of vision. With the head facing forward, unilateral mastoid vibration (500 Hz, 2 s, 136 dB force level) produced an oblique body sway with a consistent lateral component away from the stimulated ear and an average forward component. The side of stimulation had a powerful influence on the direction but not the magnitude of sway. Individuals' mean response directions were significantly clustered between subjects, as well as within subjects for 12 of 16 subjects when tested on five occasions...
November 15, 2006: Journal of Physiology
https://www.readbyqxmd.com/read/16235878/postural-sway-during-single-and-repeated-cold-exposures
#10
Tiina M Mäkinen, Hannu Rintamäki, Juha T Korpelainen, Ville Kampman, Tiina Pääkkönen, Juha Oksa, Lawrence A Palinkas, Juhani Leppäluoto, Juhani Hassi
INTRODUCTION: Tissue cooling changes sensory and neuromuscular functions that are also involved in postural control. The purpose of the study was to determine how acute and repeated exposures to cold affect whole body postural control. METHODS: Postural sway was measured from 10 subjects during standing with eyes open (EO) and closed (EC) using an inclinometer-based method. Sway was assessed at at 10 degrees C on 10 consecutive days and at 25 degrees C on days 1, 5, and 10...
October 2005: Aviation, Space, and Environmental Medicine
https://www.readbyqxmd.com/read/15869953/direction-specific-postural-instability-in-subjects-with-parkinson-s-disease
#11
COMPARATIVE STUDY
Fay B Horak, Diana Dimitrova, John G Nutt
The purpose of this study was to determine whether and why subjects with Parkinson's disease (PD) have greater instability in response to specific directions of perturbations than do age-matched control subjects and how instability is affected by stance width. This study compared postural responses to 8 directions of surface translations in PD subjects and age-matched control subjects while standing in a narrow and wide stance. PD subjects were tested in their practical OFF state. A postural stability margin was quantified as the difference between peak center of pressure (CoP) and peak center of mass (CoM) displacement in response to surface translations...
June 2005: Experimental Neurology
https://www.readbyqxmd.com/read/14762637/stiffness-and-postural-stability-in-adults-with-down-syndrome
#12
A Webber, N Virji-Babul, R Edwards, M Lesperance
The purpose of this study was to characterize postural sway in quiet standing under eyes-open and eyes-closed conditions, and to obtain a measure of postural stiffness during quiet standing in adults with Down syndrome (DS) versus control subjects. We obtained descriptive measures from centre-of-pressure (COP) data and analysed and compared COP trajectories and postural stiffness estimates from two stochastic models, the "pinned polymer" (PP) and "inverted pendulum" (IP) models. These estimates were correlated with clinical measures of muscle tone...
April 2004: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/12676410/-standing-posture-of-adults-effects-of-a-stroke
#13
COMPARATIVE STUDY
R Paillex, A So
PURPOSE: The goal of this study was to compare the standing posture of stroke patients with standing posture of healthy subjects. We have used an analysis of the centres of pressure sways. MATERIAL AND METHOD: The centres of pressure sways of the subjects were recorded on a force platform. Each subject have carried out 5 trials of 60 s while maintaining a static standing posture, with eyes opened and then closed. These sways were broken down into two spectral frequencies...
March 2003: Annales de Réadaptation et de Médecine Physique
https://www.readbyqxmd.com/read/11309458/stance-control-is-not-affected-by-paresis-and-reflex-hyperexcitability-the-case-of-spastic-patients
#14
A Nardone, M Galante, B Lucas, M Schieppati
OBJECTIVES: Spastic patients were studied to understand whether stance unsteadiness is associated with changes in the control of voluntary force, muscle tone, or reflex excitability, rather than to abnormal posture connected to the motor deficit itself. METHODS: Twenty four normal subjects, 12 patients affected by amyotrophic lateral sclerosis (ALS), seven by spastic paraparesis, and 14 by hemiparesis were studied. All patients featured various degrees of spasticity and paresis but were free from clinically evident sensory deficits...
May 2001: Journal of Neurology, Neurosurgery, and Psychiatry
https://www.readbyqxmd.com/read/7262232/relation-of-automatic-postural-responses-and-reaction-time-voluntary-movements-of-human-leg-muscles
#15
L M Nashner, P J Cordo
This study contrasts the properties of compensatory postural adjustments in response to movements of the support surface with those of reaction-time voluntary movements in human subjects. Subjects stood upon a six degrees-of-freedom movable platform and performed tone and movement-triggered voluntary sways about the ankle joints both under conditions of postural stability and instability. These triggered movements could be executed as rapidly as postural adjustments to support surface perturbations (80-120 ms), but only when the former were well practiced, single-choice (direction) and were performed under conditions of postural stability...
1981: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/1579249/skeletal-muscle-tone-and-the-misunderstood-stretch-reflex
#16
REVIEW
R A Davidoff
This review presents a revision of long-accepted tenets regarding the genesis of muscle tone in humans. Most discussions liken muscle tone in humans to the reflex tone described by Sherrington in decerebrate animals. That tradition presumes that muscle tone is fully determined by the monosynaptic stretch reflex, that tonic fusimotor activity is necessary for its production in normal humans, and that tonic muscle tone in antigravity leg muscles is responsible for the maintenance of posture. Data reviewed here show that nonreflex, mechanical mechanisms are involved in the maintenance of resting muscle tone; that spinal cord reflex responses are not stereotyped responses, but depend upon the ongoing activity in interneurons upon which inputs from a variety of peripheral sensory receptors and descending fiber systems converge; that long-latency transcortical responses are elicited when a muscle is stretched, and these responses effectively deal with large displacements; and that inertial components and viscoelastic muscle forces can counterbalance small amounts of body sway during quiet standing...
May 1992: Neurology
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