scholarly journals Influence of Stance Width on Frontal Plane Postural Dynamics and Coordination in Human Balance Control

2010 ◽  
Vol 104 (2) ◽  
pp. 1103-1118 ◽  
Author(s):  
Adam D. Goodworth ◽  
Robert J. Peterka
Keyword(s):  
Frequency Response ◽  
Balance Control ◽  
Frontal Plane ◽  
Body Motion ◽  
Upper Body ◽  
Body Sway ◽  
Support Surface ◽  
Lower Body ◽  
Stimulus Amplitude ◽  
Postural System

The influence of stance width on frontal plane postural dynamics and coordination in human bipedal stance was studied. We tested the hypothesis that when subjects adopt a narrow stance width, they will rely heavily on nonlinear control strategies and coordinated counter-phase upper and lower body motion to limit center-of-mass (CoM) deviations from upright; as stance increases, the use of these strategies will diminish. Freestanding frontal plane body sway was evoked through continuous pseudorandom rotations of the support surface on which subjects stood with various stimulus amplitudes. Subjects were either eyes open (EO) or closed (EC) and adopted various stance widths. Upper body, lower body, and CoM kinematics were summarized using root-mean-square and peak-to-peak measures, and dynamic behavior was characterized using frequency-response and impulse-response functions. In narrow stance, CoM frequency-response function gains were reduced with increasing stimulus amplitude and in EO compared with EC; in wide stance, gain reductions were much less pronounced. Results show that the narrow stance postural system is nonlinear across stimulus amplitude in both EO and EC conditions, whereas the wide stance postural system is more linear. The nonlinearity in narrow stance is likely caused by an amplitude-dependent sensory reweighting mechanism. Finally, lower body and upper body sway were approximately in-phase at low frequencies (<1 Hz) and out-of-phase at high frequencies (>1 Hz) across all stance widths, and results were therefore inconsistent with the hypothesis that subjects made greater use of coordinated counter-phase upper and lower body motion in narrow compared with wide stance conditions.

scholarly journals Stance width changes how sensory feedback is used for multisegmental balance control

2014 ◽  
Vol 112 (3) ◽  
pp. 525-542 ◽  
Author(s):  
Adam D. Goodworth ◽  
Patricia Mellodge ◽  
Robert J. Peterka
Keyword(s):  
Visual Cues ◽  
Sensory Feedback ◽  
Balance Control ◽  
Frontal Plane ◽  
Upper Body ◽  
Major Influence ◽  
Model Parameters ◽  
Stimulus Amplitude ◽  
Sensory Reweighting ◽  
Integration Model

A multilink sensorimotor integration model of frontal plane balance control was developed to determine how stance width influences the use of sensory feedback in healthy adults. Data used to estimate model parameters came from seven human participants who stood on a continuously rotating surface with three different stimulus amplitudes, with eyes open and closed, and at four different stance widths. Dependent variables included lower body (LB) and upper body (UB) sway quantified by frequency-response functions. Results showed that stance width had a major influence on how parameters varied across stimulus amplitude and between visual conditions. Active mechanisms dominated LB control. At narrower stances, with increasing stimulus amplitude, subjects used sensory reweighting to shift reliance from proprioceptive cues to vestibular and/or visual cues that oriented the LB more toward upright. When vision was available, subjects reduced reliance on proprioception and increased reliance on vision. At wider stances, LB control did not exhibit sensory reweighting. In the UB system, both active and passive mechanisms contributed and were dependent on stance width. UB control changed across stimulus amplitude most in wide stance (opposite of the pattern found in LB control). The strong influence of stance width on sensory integration and neural feedback control implies that rehabilitative therapies for balance disorders can target different aspects of balance control by using different stance widths. Rehabilitative strategies designed to assess or modify sensory reweighting will be most effective with the use of narrower stances, whereas wider stances present greater challenges to UB control.

Impairments of Postural Balance in Surgically Treated Lumbar Disc Herniation Patients

2020 ◽  
Vol 36 (4) ◽  
pp. 228-234
Author(s):  
Ziva M. Rosker ◽  
Jernej Rosker ◽  
Nejc Sarabon
Keyword(s):  
Postural Balance ◽  
Center Of Pressure ◽  
Balance Control ◽  
The Body ◽  
Surface Velocity ◽  
Body Sway ◽  
Support Surface ◽  
Balance Task ◽  
Lateral Body ◽  
Unstable Support

Reports on body sway control following microdiscectomy lack reports on side-specific balance deficits as well as the effects of trunk balance control deficits on body sway during upright stances. About 3 weeks post microdiscectomy, the body sway of 27 patients and 25 controls was measured while standing in an upright quiet stance with feet positioned parallel on an unstable support surface, a tandem stance with the involved leg positioned in front or at the back, a single-leg stance with both legs, and sitting on an unstable surface. Velocity, average amplitude, and frequency-direction–specific parameters were analyzed from the center of pressure movement, measured by the force plate. Statistically significant differences between the 2 groups were observed for the medial–lateral body sway frequency in parallel stance on a stable and unstable support surface and for the sitting balance task in medial-lateral body sway parameters. Medium to high correlations were observed between body sway during sitting and the parallel stance, as well as between the tandem and single-legged stances. Following microdiscectomy, deficits in postural balance were side specific, as expected by the nature of the pathology. In addition, the results of this study confirmed the connection between proximal balance control deficits and balance during upright quiet balance tasks.

Effects of Internal and External Attentional Focus on Postural Response to a Sliding Stance Surface

2019 ◽  
Vol 126 (3) ◽  
pp. 446-461 ◽  
Author(s):  
Hiroshi Kunimura ◽  
Masakazu Matsuoka ◽  
Naoki Hamada ◽  
Koichi Hiraoka
Keyword(s):  
Cognitive Activity ◽  
Attentional Focus ◽  
Upper Body ◽  
Body Sway ◽  
Support Surface ◽  
Postural Response ◽  
Postural Perturbation ◽  
Forward Displacement ◽  
External Focus ◽  
Internal Focus

The present study examined whether an internal or external attentional focus would affect participants’ feet-in-place balance response to postural stance perturbations. A movable platform automatically slid forward or backward while healthy participants stood on it and (a) performed no cognitive activity (control), (b) focused on the pelvis or upper body sway (internal focus), (c) memorized a number displayed immediately before the platform slid (external focus), or (d) kept the equilibrium of an unstable cylinder over the arm (external focus). The forward displacement of the pelvis induced by the platform sliding forward was smaller when participants focused on their pelvic sway, although such effect was absent when they focused on their upper body sway, indicating that the internal focus was effective for the postural response when attention was paid to the pelvic sway. Regarding an external attention focus, the forward displacement of the pelvis induced by the platform sliding forward was smaller when participants focused on the equilibrium of an unstable object over the arm, but this effect was absent when they focused on the number, indicating that an external focus was only effective when the unstable object focused upon was relevant to the equilibrium of one’s own body. No attentional intervention was effective during backward sliding of the support surface, indicating that central set for responding to postural perturbation depends on the direction of the postural perturbation.

scholarly journals Sensorimotor integration for multisegmental frontal plane balance control in humans

2012 ◽  
Vol 107 (1) ◽  
pp. 12-28 ◽  
Author(s):  
Adam D. Goodworth ◽  
Robert J. Peterka
Keyword(s):  
Time Delay ◽  
Sensory Feedback ◽  
Sensorimotor Integration ◽  
Balance Control ◽  
Frontal Plane ◽  
Impulse Response Functions ◽  
Response Functions ◽  
Stimulus Amplitude ◽  
Sensory Reweighting ◽  
Eyes Open

To quantify the contribution of sensory information to multisegmental frontal plane balance control in humans, we developed a feedback control model to account for experimental data. Subjects stood with feet close together on a surface that rotated according to a pseudorandom waveform at three different amplitudes. Experimental frequency-response functions and impulse-response functions were measured to characterize lower body (LB) and upper body (UB) motion evoked during surface rotations while subjects stood with eyes open or closed. The model assumed that corrective torques in LB and UB segments were generated with no time delay from intrinsic musculoskeletal mechanisms and with time delay from sensory feedback mechanisms. It was found that subjects' LB control was primarily based on sensory feedback. Changes in the LB control mechanisms across stimulus amplitude were consistent with the hypothesis that sensory reweighting contributed to amplitude-dependent changes in balance responses whereby subjects decreased reliance on proprioceptive cues that oriented the LB toward the surface and increased reliance on vestibular/visual cues that oriented the LB upright toward earth vertical as stimulus amplitude increased in both eyes open and closed conditions. Sensory reweighting in the LB control system also accounted for most of the amplitude-dependent changes observed in UB responses. In contrast to the LB system, sensory reweighting was not a dominant mechanism of UB control, and UB control was more influenced by intrinsic musculoskeletal mechanisms. The proposed model refines our understanding of sensorimotor integration during balance control by including multisegmental motion and explaining how intersegmental interactions influence frontal plane balance responses.

Directional Sensitivity of “First Trial” Reactions in Human Balance Control

2009 ◽  
Vol 101 (6) ◽  
pp. 2802-2814 ◽  
Author(s):  
Lars B. Oude Nijhuis ◽  
John H. J. Allum ◽  
George F. Borm ◽  
Flurin Honegger ◽  
Sebastiaan Overeem ◽  
...  
Keyword(s):  
Balance Control ◽  
Center Of Mass ◽  
Upper Body ◽  
Directional Sensitivity ◽  
Support Surface ◽  
Vestibular Cues ◽  
Human Balance ◽  
Neurophysiological Mechanisms ◽  
New Perturbation ◽  
Perturbation Direction

Support-surface movements are commonly used to examine balance control. Subjects typically receive a series of identical or randomly interspersed multidirectional balance perturbations and the atypical “first trial reaction” (evoked by the first perturbation) is often excluded from further analysis. However, this procedure may obscure vital information about neurophysiological mechanisms associated with the first perturbation and, by analogy, fully unexpected falls. We studied first trial reactions, aiming to clarify their directional impact on postural control and to characterize the underlying neurophysiological substrate. We instructed 36 subjects to maintain balance following support-surface rotations in six different directions. Perturbations in each direction were delivered in blocks, consisting of 10 serial stimuli. Full body kinematics, surface reactive forces, and electromyographic (EMG) responses were recorded. Regardless of direction, for the very first rotation, displacement of the center of mass was 15% larger compared with the ensuing nine identical rotations ( P < 0.0001). This first trial reaction immediately reemerged whenever a new perturbation direction was introduced. First trial reactions (and near-falls) were greatest for backward-directed rotations and smallest for laterally directed rotations. This directional dependence coincided with early changes in vertical head accelerations. First trial reactions in EMG responses involved larger amplitudes in general and earlier muscle response onsets in upper body muscles. These findings show that first trial reactions are associated with significantly increased postural instability, mainly due to increased response amplitudes. Although rapid habituation occurs following presentation of identical stimuli, subjects immediately become unstable again when the perturbation direction suddenly changes. Excessive responses due to a failure to combine proprioceptive and vestibular cues effectively may explain this instability seen with first trials, particularly when falling backward.

Age Effect Investigation on Postural Dynamic Responses of Human Body

2001 ◽  
Author(s):  
Maryam Hoviattalab
Keyword(s):  
Dynamic Analysis ◽  
Human Body ◽  
Balance Control ◽  
Angular Displacement ◽  
Age Groups ◽  
Dynamic Responses ◽  
Body Motion ◽  
Body Sway ◽  
Adult Age ◽  
Body Segments

Abstract Responses of human body were studied in two adult age groups. The healthy subjects with no records of falling down or occupation in a crowded and noisy environment were elected. Mean age was 24 and 71 yrs. in young and elderly groups, respectively. Four experimental tasks were presented to subjects. Two involving flat standing with open and closed eyes and two were involving imposed disturbances. Two optoelectronic camera systems were used to measure body motion. The extents of postural sway were determined by processing the recorded data from force plate. The results were compared, and also provided the basis for kinematics analysis of body segments. For dynamic analysis, we used 3-link biomechanical model on a stationary triangular foot. Results from dynamic analysis indicated that, (a) The angular displacement of body segments was larger in elderly group, especially at the trunk; (b) The visual system had a dramatic effect on balance control, and its omission along with onset of senescence, has progressive effect, i.e. increased the amplitude and frequency of body sway, up to 2.4 and 1.5 times, respectively; (c) It has been proved that, in response to sudden stimulation, body employs certain strategy for muscle contraction. “Maximum torque, occurs in ankle, and respectively diminishes in joints, on its course toward upper segments”. The point is well consistent with the literature in this contest.

scholarly journals Postural responses exhibit multisensory dependencies with discordant visual and support surface motion

2004 ◽  
Vol 14 (4) ◽  
pp. 307-319 ◽  
Author(s):  
Emily A. Keshner ◽  
Robert V. Kenyon ◽  
Jessica Langston
Keyword(s):  
Support Surface ◽  
Wide Field ◽  
Stimulus Amplitude ◽  
Visual Inputs ◽  
Postural Responses ◽  
Wide Field Of View ◽  
Postural System ◽  
Surface Translation ◽  
Anterior Posterior

The purpose of this study was to identify how the postural system weights coincident yet discordant disturbances of the visual and proprioceptive/vestibular systems. Eleven healthy subjects (25–38 yrs) received either fore-aft translations of an immersive, wide field-of-view visual environment (0.1 Hz, ± 3.7 m/sec), or anterior-posterior translations of the support surface (0.25 Hz, ± 15 cm/sec), or both concurrently. Kinematics of the head, trunk, and shank were collected with an Optotrak system and angular motion of each segment plotted across time. With only support surface translation, segmental responses were small (1°–2°) and mostly opposed the direction of sled translation. When only the visual scene was moving, segmental responses increased as the trial progressed. When the inputs were presented coincidentally, response amplitudes were large even at the onset of the trial. Mean RMS values across subjects were significantly greater with combined stimuli than for either stimulus presented alone and areas under the power curve across subjects were significantly increased at the frequency of the visual input when both inputs were presented. Thus, intra-modality dependencies were observed, such that responses to the visual inputs significantly increased and responses to the somatosensory signals reflected the stimulus amplitude only when the two inputs were combined. We believe it unlikely that the role of any single pathway contributing to postural control can be accurately characterized in a static environment if the function of that pathway is context dependent.

scholarly journals Postural threat influences vestibular-evoked muscular responses

2017 ◽  
Vol 117 (2) ◽  
pp. 604-611 ◽  
Author(s):  
Shannon B. Lim ◽  
Taylor W. Cleworth ◽  
Brian C. Horslen ◽  
Jean-Sébastien Blouin ◽  
J. Timothy Inglis ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Balance Control ◽  
Standing Balance ◽  
Medial Gastrocnemius ◽  
Trunk Muscles ◽  
Support Surface ◽  
Evoked Responses ◽  
Lower Body ◽  
Leg Muscles ◽  
Postural Threat

Standing balance is significantly influenced by postural threat. While this effect has been well established, the underlying mechanisms of the effect are less understood. The involvement of the vestibular system is under current debate, and recent studies that investigated the effects of height-induced postural threat on vestibular-evoked responses provide conflicting results based on kinetic (Horslen BC, Dakin CJ, Inglis JT, Blouin JS, Carpenter MG. J Physiol 592: 3671–3685, 2014) and kinematic (Osler CJ, Tersteeg MC, Reynolds RF, Loram ID. Eur J Neurosci 38: 3239–3247, 2013) data. We examined the effect of threat of perturbation, a different form of postural threat, on coupling (cross-correlation, coherence, and gain) of the vestibulo-muscular relationship in 25 participants who maintained standing balance. In the “No-Threat” conditions, participants stood quietly on a stable surface. In the “Threat” condition, participants' balance was threatened with unpredictable mediolateral support surface tilts. Quiet standing immediately before the surface tilts was compared to an equivalent time from the No-Threat conditions. Surface EMG was recorded from bilateral trunk, hip, and leg muscles. Hip and leg muscles exhibited significant increases in peak cross-correlation amplitudes, coherence, and gain (1.23–2.66×) in the Threat condition compared with No-Threat conditions, and significant correlations were observed between threat-related changes in physiological arousal and medium-latency peak cross-correlation amplitude in medial gastrocnemius ( r = 0.408) muscles. These findings show a clear threat effect on vestibular-evoked responses in muscles in the lower body, with less robust effects of threat on trunk muscles. Combined with previous work, the present results can provide insight into observed changes during balance control in threatening situations. NEW & NOTEWORTHY This is the first study to show increases in vestibular-evoked responses of the lower body muscles under conditions of increased threat of postural perturbation. While robust findings were observed in hip and leg muscles, less consistent results were found in muscles of the trunk. The present findings provide further support in the ongoing debate for arguments that vestibular-evoked balance responses are influenced by fear and anxiety and explain previous threat-related changes in balance.

scholarly journals Use of galvanic vestibular feedback to control postural orientation in decerebrate rabbits

2012 ◽  
Vol 107 (11) ◽  
pp. 3020-3026 ◽  
Author(s):  
P. V. Zelenin ◽  
L.-J. Hsu ◽  
G. N. Orlovsky ◽  
T. G. Deliagina
Keyword(s):  
Balance Control ◽  
Simple Algorithm ◽  
Vestibular Stimulation ◽  
Dorsal Side ◽  
The Body ◽  
Body Sway ◽  
Lateral Stability ◽  
Postural Perturbation ◽  
Lateral Body ◽  
Postural System

In quadrupeds, the dorsal-side-up body orientation during standing is maintained due to a postural system that is driven by feedback signals coming mainly from limb mechanoreceptors. In caudally decerebrated (postmammillary) rabbits, the efficacy of this system is considerably reduced. In this paper, we report that the efficacy of postural control in these animals can be restored with galvanic vestibular stimulation (GVS) applied transcutaneously to the labyrinths. In standing intact rabbits, GVS causes a lateral body sway towards the positive electrode. We used this GVS-caused sway to counteract the lateral body sway resulting from a mechanical perturbation of posture. Experiments were performed on postmammillary rabbits that stood on the tilting platform with their hindlimbs. To make the GVS value dependent on the postural perturbation (i.e., on the lateral body sway caused by tilt of the platform), an artificial feedback loop was formed in the following ways: 1) Information about the body sway was provided by a mechanical sensor; 2) The GVS current was applied when the sway exceeded a threshold value; the polarity of the current was determined by the sway direction. This simple algorithm allowed the “hybrid” postural system to maintain the dorsal-side-up orientation of the hindquarters when the platform was tilted by ± 20°. Thus, an important postural function, i.e., securing lateral stability during standing, can be restored in decerebrate rabbits with the GVS-based artificial feedback. We suggest that such a control system can compensate for the loss of lateral stability of various etiologies, and can be used for restoration of balance control in patients with impaired postural functions.

Sensorimotor Integration in Human Postural Control

2002 ◽  
Vol 88 (3) ◽  
pp. 1097-1118 ◽  
Author(s):  
R. J. Peterka
Keyword(s):  
Control System ◽  
Time Delay ◽  
Feedback Control ◽  
Sensorimotor Integration ◽  
Normal Subjects ◽  
Body Sway ◽  
Support Surface ◽  
Stimulus Amplitude ◽  
Stimulus Response ◽  
Response Data

It is generally accepted that human bipedal upright stance is achieved by feedback mechanisms that generate an appropriate corrective torque based on body-sway motion detected primarily by visual, vestibular, and proprioceptive sensory systems. Because orientation information from the various senses is not always available (eyes closed) or accurate (compliant support surface), the postural control system must somehow adjust to maintain stance in a wide variety of environmental conditions. This is the sensorimotor integration problem that we investigated by evoking anterior-posterior (AP) body sway using pseudorandom rotation of the visual surround and/or support surface (amplitudes 0.5–8°) in both normal subjects and subjects with severe bilateral vestibular loss (VL). AP rotation of body center-of-mass (COM) was measured in response to six conditions offering different combinations of available sensory information. Stimulus-response data were analyzed using spectral analysis to compute transfer functions and coherence functions over a frequency range from 0.017 to 2.23 Hz. Stimulus-response data were quite linear for any given condition and amplitude. However, overall behavior in normal subjects was nonlinear because gain decreased and phase functions sometimes changed with increasing stimulus amplitude. “Sensory channel reweighting” could account for this nonlinear behavior with subjects showing increasing reliance on vestibular cues as stimulus amplitudes increased. VL subjects could not perform this reweighting, and their stimulus-response behavior remained quite linear. Transfer function curve fits based on a simple feedback control model provided estimates of postural stiffness, damping, and feedback time delay. There were only small changes in these parameters with increasing visual stimulus amplitude. However, stiffness increased as much as 60% with increasing support surface amplitude. To maintain postural stability and avoid resonant behavior, an increase in stiffness should be accompanied by a corresponding increase in damping. Increased damping was achieved primarily by decreasing the apparent time delay of feedback control rather than by changing the damping coefficient (i.e., corrective torque related to body-sway velocity). In normal subjects, stiffness and damping were highly correlated with body mass and moment of inertia, with stiffness always about 1/3 larger than necessary to resist the destabilizing torque due to gravity. The stiffness parameter in some VL subjects was larger compared with normal subjects, suggesting that they may use increased stiffness to help compensate for their loss. Overall results show that the simple act of standing quietly depends on a remarkably complex sensorimotor control system.

Sign in / Sign up

Export Citation Format

Share Document