scholarly journals Postural Responses Evoked by Platform Pertubations Are Dominated by Continuous Feedback

2007 ◽  
Vol 98 (2) ◽  
pp. 730-743 ◽  
Author(s):  
Herman van der Kooij ◽  
Erwin de Vlugt
Keyword(s):  
Balance Control ◽  
The Body ◽  
Body Sway ◽  
Intermittent Control ◽  
Feedback Mechanisms ◽  
Ankle Torque ◽  
Eyes Closed ◽  
Postural Responses ◽  
Continuous Feedback ◽  
Time Invariant

Is human balance control dominated by time invariant continuous feedback mechanisms or do noncontinuous mechanisms play a significant role like intermittent control? The goal of this paper is to quantify how much of the postural responses evoked by pseudorandom external periodic perturbations can be explained by continuous time invariant feedback control. Nine healthy subjects participated in this study. Center of mass and ankle torque responses were elicited by periodic platform perturbations in forward-backward directions containing energy in the 0.06- to 4.5-Hz frequency band. Subjects had their eyes open (EO) or eyes closed (EC). Responses were decomposed into a periodic component and a remnant (stochastic) component using spectral analysis. It is concluded that periodic responses can explain most of the evoked responses, although the remnant power spectral densities (PSDs) were significant especially for slow responses (<0.2 Hz) and largest for EC. The found remnant PSD did depend on the sensory condition but not on the platform perturbation amplitude. The ratio of the body sway and ankle torque remnant PSD reflects the body dynamics. Both findings are consistent with the idea that estimation of body orientation is part of a continuous feedback loop and that (stochastic) estimation errors increase when one source of sensory information is removed. The findings are not consistent with the idea that discrete or discontinuous intermittent feedback mechanisms significantly shape postural responses.

scholarly journals Reactive Postural Responses to Continuous Yaw Perturbations in Healthy Humans: The Effect of Aging

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 63 ◽  
Author(s):  
Ilaria Mileti ◽  
Juri Taborri ◽  
Stefano Rossi ◽  
Zaccaria Del Prete ◽  
Marco Paoloni ◽  
...  
Keyword(s):  
Older Adults ◽  
Balance Control ◽  
Center Of Mass ◽  
Community Dwelling ◽  
Body Segments ◽  
Healthy Humans ◽  
Eyes Closed ◽  
Age Related ◽  
Postural Responses ◽  
Mass Displacement

Maintaining balance stability while turning in a quasi-static stance and/or in dynamic motion requires proper recovery mechanisms to manage sudden center-of-mass displacement. Furthermore, falls during turning are among the main concerns of community-dwelling elderly population. This study investigates the effect of aging on reactive postural responses to continuous yaw perturbations on a cohort of 10 young adults (mean age 28 ± 3 years old) and 10 older adults (mean age 61 ± 4 years old). Subjects underwent external continuous yaw perturbations provided by the RotoBit1D platform. Different conditions of visual feedback (eyes opened and eyes closed) and perturbation intensity, i.e., sinusoidal rotations on the horizontal plane at different frequencies (0.2 Hz and 0.3 Hz), were applied. Kinematics of axial body segments was gathered using three inertial measurement units. In order to measure reactive postural responses, we measured body-absolute and joint absolute rotations, center-of-mass displacement, body sway, and inter-joint coordination. Older adults showed significant reduction in horizontal rotations of body segments and joints, as well as in center-of-mass displacement. Furthermore, older adults manifested a greater variability in reactive postural responses than younger adults. The abnormal reactive postural responses observed in older adults might contribute to the well-known age-related difficulty in dealing with balance control during turning.

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.

Analysis of Physiological Signals of Individuals with Eyes Closed Subjected to Unexpected Direction-Specific Stimuli Causing Instability

2020 ◽  
Vol 10 (11) ◽  
pp. 2754-2763
Author(s):  
Sunhye Shin ◽  
Chul Un Hong ◽  
Kyong Kim ◽  
Tae Kyu Kwon
Keyword(s):  
Lower Extremity ◽  
Muscle Activity ◽  
Postural Balance ◽  
Balance Control ◽  
Center Of Gravity ◽  
Training System ◽  
The Body ◽  
Physiological Signals ◽  
Eyes Closed ◽  
Lower Extremity Muscle

Research regarding the cerebral cortex and muscle activity patterns of the body used for postural balance control when sudden instability stimuli occur is lacking. This study analyzed individuals' physiological signals when direction-specific instability stimuli were applied while their eyes were closed. Healthy adults in their 20s maintained their postural balance while looking at the center of gravity provided by a monitor with a three-dimensional dynamic postural balance training system. We performed electroencephalography (EEG) and measured trunk and lower extremity muscle activity of participants with their eyes closed when subjected to four direction-specific instability stimuli (anterior, posterior, left, and right). EEG results showed that gamma waves increased significantly with an unbalanced stimulus when the participant's eyes were open and closed. The increased gamma wave rate with eyes closed was low in the exercise planning area, where information is relatively integrated and exercise is planned without visual information. EMG results showed fewer gamma waves on EEG due to the low focus on postural control because participants could not observe the center of gravity, which is the basis for balance. The trunk and lower extremity muscles tended to be used more due to the larger body perturbation angle. These outcomes can be used as basic data regarding how the human brain and muscles maintain postural balance when an unexpected external instability stimulus occurs. Quantitative postural balance rehabilitation training protocols for the elderly and those with disabilities can be created based on these outcomes.

scholarly journals Visual Modulation of Human Responses to Support Surface Translation

2021 ◽  
Vol 15 ◽  
Author(s):  
Mustafa Emre Akçay ◽  
Vittorio Lippi ◽  
Thomas Mergner
Keyword(s):  
Inverted Pendulum ◽  
Significant Degree ◽  
The Body ◽  
Resonance Phenomenon ◽  
Continuous Illumination ◽  
Support Surface ◽  
Position Information ◽  
Eyes Closed ◽  
Postural Responses ◽  
Visual Conditions

Vision is known to improve human postural responses to external perturbations. This study investigates the role of vision for the responses to continuous pseudorandom support surface translations in the body sagittal plane in three visual conditions: with the eyes closed (EC), in stroboscopic illumination (EO/SI; only visual position information) and with eyes open in continuous illumination (EO/CI; position and velocity information) with the room as static visual scene (or the interior of a moving cabin, in some of the trials). In the frequency spectrum of the translation stimulus we distinguished on the basis of the response patterns between a low-frequency, mid-frequency, and high-frequency range (LFR: 0.0165-0.14 Hz; MFR: 0.15–0.57 Hz; HFR: 0.58–2.46 Hz). With EC, subjects’ mean sway response gain was very low in the LFR. On average it increased with EO/SI (although not to a significant degree p = 0.078) and more so with EO/CI (p &lt; 10−6). In contrast, the average gain in the MFR decreased from EC to EO/SI (although not to a significant degree, p = 0.548) and further to EO/CI (p = 0.0002). In the HFR, all three visual conditions produced, similarly, high gain levels. A single inverted pendulum (SIP) model controlling center of mass (COM) balancing about the ankle joints formally described the EC response as being strongly shaped by a resonance phenomenon arising primarily from the control’s proprioceptive feedback loop. The effect of adding visual information in these simulations lies in a reduction of the resonance, similar as in the experiments. Extending the model to a double inverted pendulum (DIP) suggested in addition a biomechanical damping effective from trunk sway in the hip joints on the resonance.

scholarly journals Different visual manipulations have similar effects on quasi-static and dynamic balance responses of young and older people

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11221
Author(s):  
Daniel Schmidt ◽  
Felipe P. Carpes ◽  
Thomas L. Milani ◽  
Andresa M.C. Germano
Keyword(s):  
Older Adults ◽  
Balance Control ◽  
Dynamic Balance ◽  
Visual Deprivation ◽  
Elderly Persons ◽  
Eyes Closed ◽  
Balance Tests ◽  
Postural Responses ◽  
Eyes Open ◽  
Visual Conditions

Background Studies demonstrated that the older adults can be more susceptible to balance instability after acute visual manipulation. There are different manipulation approaches used to investigate the importance of visual inputs on balance, e.g., eyes closed and blackout glasses. However, there is evidence that eyes open versus eyes closed results in a different organization of human brain functional networks. It is, however, unclear how different visual manipulations affect balance, and whether such effects differ between young and elderly persons. Therefore, this study aimed to determine whether different visual manipulation approaches affect quasi-static and dynamic balance responses differently, and to investigate whether balance responses of young and older adults are affected differently by these various visual conditions. Methods Thirty-six healthy participants (20 young and 16 older adults) performed balance tests (quasi-static and unexpected perturbations) under four visual conditions: Eyes Open, Eyes Closed, Blackout Glasses, and Dark Room. Center of pressure (CoP) and muscle activation (EMG) were quantified. Results As expected, visual deprivation resulted in larger CoP excursions and higher muscle activations during balance tests for all participants. Surprisingly, the visual manipulation approach did not influence balance control in either group. Furthermore, quasi-static and dynamic balance control did not differ between young or older adults. The visual system plays an important role in balance control, however, similarly for both young and older adults. Different visual deprivation approaches did not influence balance results, meaning our results are comparable between participants of different ages. Further studies should investigate whether a critical illumination level may elicit different postural responses between young and older adults.

scholarly journals Dynamic Balance Measurement and Quantitative Assessment Using Wearable Plantar-Pressure Insoles in a Pose-Sensed Virtual Environment

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4193 ◽  
Author(s):  
Cunguang Lou ◽  
Chenyao Pang ◽  
Congrui Jing ◽  
Shuo Wang ◽  
Xufeng He ◽  
...  
Keyword(s):  
Plantar Pressure ◽  
Evaluation System ◽  
Balance Control ◽  
Dynamic Balance ◽  
Sports Injury ◽  
The Body ◽  
Assessment Process ◽  
Body Sway ◽  
Kinect Sensor ◽  
Sit To Stand

The center of plantar pressure (COP) reflects the dynamic balance of subjects to a certain extent. In this study, wearable pressure insoles are designed, body pose measure is detected by the Kinect sensor, and a balance evaluation system is formulated. With the designed games for the interactive actions, the Kinect sensor reads the skeletal poses to judge whether the desired action is performed, and the pressure insoles simultaneously collect the plantar pressure data. The COP displacement and its speed are calculated to determine the body sway and the ability of balance control. Significant differences in the dispersion of the COP distribution of the 12 subjects have been obtained, indicating different balancing abilities of the examined subjects. A novel assessment process is also proposed in the paper, in which a correlation analysis is made between the de facto sit-to-stand (STS) test and the proposed method; the Pearson and Spearman correlations are also conducted, which reveal a significant positive correlation. Finally, four undergraduate volunteers with a right leg sports injury participate in the experiments. The experimental results show that the normal side and abnormal side have significantly different characters, suggesting that our method is effective and robust for balance measurements.

scholarly journals The effect of music on body sway when standing in a moving virtual environment

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0258000
Author(s):  
Shaquitta Dent ◽  
Kelley Burger ◽  
Skyler Stevens ◽  
Benjamin D. Smith ◽  
Jefferson W. Streepey
Keyword(s):  
Virtual Reality ◽  
Virtual Environment ◽  
Center Of Pressure ◽  
Force Plate ◽  
The Body ◽  
Body Sway ◽  
Visual Environment ◽  
Auditory Information ◽  
Eyes Closed ◽  
Do So

Movement of the visual environment presented through virtual reality (VR) has been shown to invoke postural adjustments measured by increased body sway. The effect of auditory information on body sway seems to be dependent on context with sounds such as white noise, tones, and music being used to amplify or suppress sway. This study aims to show that music manipulated to match VR motion further increases body sway. Twenty-eight subjects stood on a force plate and experienced combinations of 3 visual conditions (VR translation in the AP direction at 0.1 Hz, no translation, and eyes closed) and 4 music conditions (Mozart’s Jupiter Symphony modified to scale volume at 0.1 Hz and 0.25 Hz, unmodified music, and no music) Body sway was assessed by measuring center of pressure (COP) velocities and RMS. Cross-coherence between the body sway and the 0.1 Hz and 0.25 Hz stimuli was also determined. VR translations at 0.1 Hz matched with 0.1Hz shifts in music volume did not lead to more body sway than observed in the no music and unmodified music conditions. Researchers and clinicians may consider manipulating sound to enhance VR induced body sway, but findings from this study would not suggest using volume to do so.

scholarly journals Direction-Specific Instability Poststroke Is Associated With Deficient Motor Modules for Balance Control

2018 ◽  
Vol 32 (6-7) ◽  
pp. 655-666 ◽  
Author(s):  
Digna de Kam ◽  
Alexander C. Geurts ◽  
Vivian Weerdesteyn ◽  
Gelsy Torres-Oviedo
Keyword(s):  
Balance Control ◽  
Postural Instability ◽  
Trunk Muscles ◽  
Patient Specific ◽  
Body Sway ◽  
Stroke Survivors ◽  
Muscle Coordination ◽  
Targeted Interventions ◽  
Postural Responses ◽  
Long Latency

Defective muscle coordination for balance recovery may contribute to stroke survivors’ propensity for falling. Thus, we investigated deficits in muscle coordination for postural control and their association to body sway following balance perturbations in people with stroke. Specifically, we compared the automatic postural responses of 8 leg and trunk muscles recorded bilaterally in unimpaired individuals and those with mild to moderate impairments after unilateral supratentorial lesions (>6 months). These responses were elicited by unexpected floor translations in 12 directions. We extracted motor modules (ie, muscle synergies) for each leg using nonnegative matrix factorization. We also determined the magnitude of perturbation-induced body sway using a single-link inverted pendulum model. Whereas the number of motor modules for balance was not affected by stroke, those formed by muscles with long latency responses were replaced by atypically structured paretic motor modules (atypical muscle groupings), which hints at direct cerebral involvement in long-latency feedback responses. Other paretic motor modules had intact structure but were poorly recruited, which is indicative of indirect cerebral control of balance. Importantly, these paretic deficits were strongly associated with postural instability in the preferred activation direction of the impaired motor modules. Finally, these deficiencies were heterogeneously distributed across stroke survivors with lesions in distinct locations, suggesting that different cerebral substrates may contribute to balance control. In conclusion, muscle coordination deficits in the paretic limb of stroke survivors result in direction-specific postural instability, which highlights the importance of targeted interventions to address patient-specific balance impairments.

scholarly journals Does the Fatigue Index Induced in Athlete’s Affect Static Balance?

2019 ◽  
Vol 8 (5) ◽  
pp. 81
Author(s):  
Recep Soslu
Keyword(s):  
Anaerobic Power ◽  
Balance Training ◽  
The Body ◽  
Static Balance ◽  
Fatigue Index ◽  
Eyes Closed ◽  
Post Test ◽  
Eyes Open ◽  
Continuous Feedback ◽  
Base Of Support

Balance is the process of maintaining the body center of gravity vertically over the base of support and relies on rapid, continuous feedback and integration of afferent information coming from three sensory components, that is somatosensory, visual, and vestibular systems, resulting in smooth and coordinated neuromuscular actions. To investigate the effects of fatigue index on the static balance of sportsmen. A total of 51 male elite sportsmen from 4 different sports branches (Football players: 19, Volleyball players: 13, Skiers: 10 and Athletes: 9) participated in the study. The Wingate anaerobic power and capacity test was applied to induce fatigue. The Technobody isokinetic balance meter (Pro-Kin. CSMI) was used to measure pre- and post-fatigue static balance. There was a significant interaction between dependent (pre and post test balance) and independent (test statue and sport branches) variables were observed (F(63,1031.14) = 1.59, &eta;2 = .07, p ˂ .05). Main effect results showed that pre-fatigue balance values were significantly different than post-fatigue balance values in all groups (F(1.14, 213.91) = 177.99, &eta;2 = .49, p ˂ .05).Moreover, significant differences were identified between pre- and post-fatigue test results in sport branches (F(3.188) = 4.12, ƞ2 = .06, p &lt; .05) and test statue (eyes open and closed) (F(3.188) = 3.32, ƞ2 = .05, p &lt; .05). Bonferonni follow-up test indicated that there was a significant increase from footballers&rsquo; average static balance to the athletes&rsquo; average static balance (p ˂ .05). In test statue, pre fatigue eyes closed values were significantly different than post fatigue eyes opened values (p ˂ .05). Static balance training should be included in the training to be performed, fatigue static balance training should be performed in team and individual sports and the content of the training should be reorganized in line with the results obtained.

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.

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