scholarly journals Development of a theoretical model for upright postural control in lower limb prosthesis users

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
David F. Rusaw ◽  
Rasmus Alinder ◽  
Sigurd Edholm ◽  
Karin L. L. Hallstedt ◽  
Jessika Runesson ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Postural Control ◽  
Inverted Pendulum ◽  
Weight Bearing ◽  
Correlation Coefficients ◽  
Quiet Standing ◽  
Control Group ◽  
Eyes Closed ◽  
Lower Limb Prosthesis ◽  
Eyes Open

AbstractMethods used to assess quiet standing in unilateral prosthesis users often assume validity of an inverted pendulum model despite this being shown as invalid in some instances. The aim of the current study was to evaluate the validity of a proposed unilaterally-constrained pin-controller model in explaining postural control in unilateral prosthesis users. Prosthesis users were contrasted against the theoretical model as were able-bodied controls that stood on a platform which unilaterally constrained movement of the CoP. All participants completed bouts of quiet standing with eyes open, eyes closed and with feedback on inter-limb weight bearing asymmetry. Correlation coefficients were used to infer inverted pendulum behavior in both the anteroposterior and mediolateral directions and were derived from both kinematic (body attached markers) and kinetic (centre of pressure) experimental data. Larger, negative correlation coefficients reflected better model adherence, whilst low or no correlation reflected poorer model adherence. Inverted pendulum behavior derived from kinematic data, indicated coefficients of high magnitude in both mediolateral (all cases range 0.71–0.78) and anteroposterior (0.88–0.91) directions, irrespective of groups. Inverted pendulum behavior derived from kinetic data in the anteroposterior direction indicated validity of the model with large negative coefficients associated with the unconstrained/intact limbs (prosthesis users: − 0.45 to − 0.65, control group: − 0.43 to − 0.72), small coefficients in constrained/prosthetic limbs (prosthesis users: − 0.02 to 0.07, control group: 0.13–0.26) and large negative coefficients in combined conditions (prosthesis users: − 0.36 to − 0.56, control group: − 0.71 to − 0.82). For the mediolateral direction, coefficients were negligible for individual limbs (0.03–0.17) and moderate to large negative correlations, irrespective of group (− 0.31 to − 0.73). Data suggested both prosthesis users’ and able-bodied individuals’ postural control conforms well to that predicted by a unilaterally-constrained pin-controller model, which has implications for the fundamental control of posture in transtibial prosthesis users.

scholarly journals Maximal stability limits in adolescents with Tourette syndrome

2021 ◽  
Vol 4 (1) ◽  
pp. 013-022
Author(s):  
Blanchet Mariève ◽  
Prince François ◽  
Lemay Martin ◽  
Chouinard Sylvain ◽  
Messier Julie
Keyword(s):  
Postural Control ◽  
Tourette Syndrome ◽  
Center Of Pressure ◽  
Phase 1 ◽  
Sensory Information ◽  
Control Group ◽  
Eyes Closed ◽  
Highly Sensitive ◽  
Eyes Open ◽  
Stability Limits

We explored if adolescents with Gilles de la Tourette syndrome (GTS) had functional postural control impairments and how these deficits are linked to a disturbance in the processing and integration of sensory information. We evaluated the displacements of the center of pressure (COP) during maximal leaning in four directions (forward, backward, rightward, leftward) and under three sensory conditions (eyes open, eyes closed, eyes closed standing on foam). GTS adolescents showed deficits in postural stability and in lateral postural adjustments but they had similar maximal COP excursion than the control group. The postural performance of the GTS group was poorer in the eyes open condition (time to phase 1 onset, max-mean COP). Moreover, they displayed a poorer ability to maintain the maximum leaning position under the eyes open condition during mediolateral leaning tasks. By contrast, during forward leaning, they showed larger min-max ranges than control subjects while standing on the foam with the eyes closed. Together, these findings support the idea that GTS produces subclinical postural control deficits. Importantly, our results suggest that postural control disorders in GTS are highly sensitive to voluntary postural leaning tasks which have high demand for multimodal sensory integration.

scholarly journals Postural control in girls with adolescent idiopathic scoliosis while wearing a Chêneau brace or performing active self-correction: a pilot study

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7513 ◽  
Author(s):  
Elżbieta Piątek ◽  
Michał Kuczyński ◽  
Bożena Ostrowska
Keyword(s):  
Fractal Dimension ◽  
Adolescent Idiopathic Scoliosis ◽  
Idiopathic Scoliosis ◽  
Postural Control ◽  
Reciprocal Relationship ◽  
Quiet Standing ◽  
Quiet Stance ◽  
Therapeutic Modalities ◽  
Eyes Closed ◽  
Eyes Open

Background It is known that adolescent idiopathic scoliosis (AIS) is often accompanied by balance deficits. This reciprocal relationship must be taken into account when prescribing new therapeutic modalities because these may differently affect postural control, interacting with therapy and influencing its results. Objective The purpose was to compare postural control in girls with AIS while wearing the Chêneau brace (BRA) or performing active self-correction (ASC) with their postural control in a quiet comfortable stance. Methods Nine subjects were evaluated on a force plate in three series of two 20-s quiet standing trials with eyes open or closed; three blocks were randomly arranged: normal quiet stance (QST), quiet stance with BRA, and quiet stance with ASC. On the basis of centre-of-pressure (COP) recordings, the spatial and temporal COP parameters were computed. Results and Discussion Performing ASC was associated with a significant backward excursion of the COP mean position with eyes open and closed (ES = 0.56 and 0.65, respectively; p < 0.05). This excursion was accompanied by an increase in the COP fractal dimension (ES = 1.05 and 0.98; p < 0.05) and frequency (ES = 0.78; p = 0.10 and ES = 1.14; p < 0.05) in the mediolateral (ML) plane. Finally, both therapeutic modalities decreased COP sample entropy with eyes closed in the anteroposterior (AP) plane. Wearing BRA resulted in ES = 1.45 (p < 0.05) while performing ASC in ES = 0.76 (p = 0.13). Conclusion The observed changes in the fractal dimension (complexity) and frequency caused by ASC account for better adaptability of patients to environmental demands and for their adequate resources of available postural strategies in the ML plane. These changes in sway structure were accompanied by a significant (around 25 mm) backward excursion of the mean COP position. However, this improvement was achieved at the cost of lower automaticity, i.e. higher attentional involvement in postural control in the AP plane. Wearing BRA may have an undesirable effect on some aspects of body balance.

scholarly journals Variability in Postural Control With and Without Balance-Based Torso- Weighting in People With Multiple Sclerosis and Healthy Controls

2014 ◽  
Vol 94 (10) ◽  
pp. 1489-1498 ◽  
Author(s):  
Charlotte M. Hunt ◽  
Gail Widener ◽  
Diane D. Allen
Keyword(s):  
Multiple Sclerosis ◽  
Postural Control ◽  
Repeated Measures ◽  
Center Of Pressure ◽  
Quiet Standing ◽  
Healthy Controls ◽  
Movement Variability ◽  
Lateral Direction ◽  
Eyes Closed ◽  
Eyes Open

Background People with multiple sclerosis (MS) have diminished postural control, and center of pressure (COP) displacement varies more in this population than in healthy controls. Balance-based torso-weighting (BBTW) can improve clinical balance and mobility in people with MS, and exploration using both linear and nonlinear measures of COP may help determine whether BBTW optimizes movement variability. Objective The aim of this study was to investigate the effects of BBTW on people with MS and healthy controls during quiet standing. Design This was a quasi-experimental study comparing COP variability between groups, between eye closure conditions, and between weighting conditions in the anterior-posterior and medial-lateral directions. Methods Twenty participants with MS and 18 healthy controls stood on a forceplate in 4 conditions: eyes open and closed and with and without BBTW. Linear measures of COP displacement included range and root mean square (RMS). Nonlinear measures included approximate entropy (ApEn) and Lyapunov exponent (LyE). Three-way repeated-measures analyses of variance compared measures across groups and conditions. The association between weighting response and baseline nonlinear variables was examined. When significant associations were found, MS subgroups were created and compared. Results The MS and control groups had significantly different range, RMS, and ApEn values. The eyes-open and eyes-closed conditions had significantly different range and RMS values. Change with weighting correlated with LyE (r=−.70) and ApEn (r=−.59). Two MS subgroups, with low and high baseline LyE values, responded to BBTW in opposite directions, with a significant main effect for weighting condition for the LyE variable in the medial-lateral direction. Limitations The small samples and no identification of impairments related to LyE at baseline were limitations of the study. Conclusions The LyE may help differentiate subgroups who respond differently to BBTW. In both subgroups, LyE values moved toward the average of healthy controls, suggesting that BBTW may help optimize movement variability in people with MS.

Effects of Balance Training on Postural Stability

2002 ◽  
Vol 46 (13) ◽  
pp. 1237-1240
Author(s):  
Jennifer M. Schmit ◽  
Deanna I. Rejacques ◽  
Michael A. Riley
Keyword(s):  
Postural Control ◽  
Postural Sway ◽  
Balance Training ◽  
Control Group ◽  
Significant Group ◽  
Eyes Closed ◽  
Eyes Open ◽  
Group 2 ◽  
Main Effects ◽  
The Relationship

The present study is designed to address the relationship between postural sway and balance training. We compared postural sway in a group of trained dancers to a group of physically fit, untrained participants (control group) in order to assess enhanced postural control with balance training, particularly under challenging balance conditions. We varied the difficulty of postural control by using two surface conditions (rigid surface, foam surface) and two visual conditions (eyes open, eyes closed), factorially combined. The data were evaluated using 1-between (group) × 2-within (vision and surface) analyses of variance (ANOVA). The three dependent variables were the standard deviation of the COP time series in the anterior-posterior (AP) and medial-lateral (ML) axes, and the COP path length. Significant main effects were found for surface and vision and the surface*vision interaction in all conditions. Significant group differences were found in the AP and ML axes. The results of this study indicate that balance training enhances the control of posture. Thus, it may be useful to provide balance training to workers who must operate under conditions that threaten balance.

Unsupported Eyes Closed Sitting and Quiet Standing Share Postural Control Strategies in Healthy Individuals

Motor Control ◽  
2015 ◽  
Vol 19 (1) ◽  
pp. 10-24 ◽  
Author(s):  
Murielle Grangeon ◽  
Cindy Gauthier ◽  
Cyril Duclos ◽  
Jean-Francois Lemay ◽  
Dany Gagnon
Keyword(s):  
Postural Control ◽  
Center Of Pressure ◽  
Control Strategies ◽  
Standing Position ◽  
The Body ◽  
Quiet Standing ◽  
Healthy Individuals ◽  
Eyes Closed ◽  
Eyes Open ◽  
Almost All

The study aimed to (1) compare postural stability between sitting and standing in healthy individuals and (2) define center-of-pressure (COP) measures during sitting that could also explain standing stability. Fourteen healthy individuals randomly maintained (1) two short-sitting positions with eyes open or closed, with or without hand support, and (2) one standing position with eyes open with both upper limbs resting alongside the body. Thirty-six COP measures based on time and frequency series were computed. Greater COP displacement and velocity along with lower frequency measures were found for almost all directional components during standing compared with both sitting positions. The velocity, 95% confidence ellipse area, and centroidal frequency were found to be correlated between unsupported sitting and standing. Despite evidenced differences between sitting and standing, similarities in postural control were highlighted when sitting stability was the most challenging. These findings support further investigation between dynamic sitting and standing balance.

scholarly journals Changes in the Sensory Weighting Strategies in Balance Control throughout Maturation in Children

2020 ◽  
Author(s):  
Solara Sinno ◽  
Georges Dumas ◽  
Art Mallinson ◽  
Fadi Najem ◽  
Kim Smith Abouchacra ◽  
...  
Keyword(s):  
Postural Control ◽  
Control Group ◽  
Healthy Children ◽  
Child Assessment ◽  
Positive Correlation ◽  
Sensory Inputs ◽  
Eyes Closed ◽  
Anthropometric Characteristics ◽  
Eyes Open ◽  
Sensory Weighting

Abstract Background The central nervous system integrates information from different sensory inputs (vestibular, visual, and somatosensory) to maintain balance. However, strategies for weighing sensory information change as maturation occurs. Purpose The purpose of this study was to: (1) evaluate postural control development in a large sample of healthy children aged 5 to 17 years old, (2) analyze changes in sensory weighting strategies as maturation occurs, and (3) determine the extent to which anthropometric characteristics (height, weight, body mass index [BMI]) influence postural control. Sample Size This study recruited 120 healthy children, equally distributed in gender and number, into four age groups (5–8 years, 9–11 years, 12–14 years, and 15–17 years) and compared them to a control group of 20 healthy adults (aged 20–25 years). Research Design The sensory organization test (SOT) was used to assess overall balance and the use of specific sensory inputs to maintain postural control. All children underwent the six SOT conditions: (1) eyes open, surround and platform stable, (2) eyes closed, surround and platform stable, (3) eyes open, sway-referenced surround, platform stable, (4) eyes open, sway-referenced platform, (5) eyes closed, sway-referenced platform, and (6) eyes open, sway-referenced surround and platform. Data Analysis Condition-specific equilibrium scores (ES), composite equilibrium scores (CES), and sensory analysis ratios were analyzed to determine whether the performance was related to age, gender, or specific anthropometric characteristics (height, weight, and BMI). Results Data showed a significant age-associated improvement in ES for all 6 conditions (p < 0.05) and in CES (p = 0.001). For both genders, (1) somatosensory function was adult-like by age 5 to 8 years, (2) visual function peaked around age 12 years, and (3) vestibular function reached maturity by age 15 to 17 years (p < 0.05). A moderate positive correlation (r(140) = 0.684, p = 0.01; two-tailed) between height and CES was found and a weak positive correlation (r(140) = 0.198, p = 0.01) between height and somatosensory ratio was noted. Lower vestibular ratio scores were observed in children who had a higher BMI (p = 0.001). Conclusion The efficient use of individual sensory system input to maintain balance does not occur at the same age. Age and gender affect the changes in sensory weighting strategies, while height and BMI influence postural control in children. These factors need to be accounted for in child assessment.

scholarly journals EEG Data Quality: Determinants and Impact in a Multicenter Study of Children, Adolescents, and Adults with Attention-Deficit/Hyperactivity Disorder (ADHD)

2021 ◽  
Vol 11 (2) ◽  
pp. 214
Author(s):  
Anna Kaiser ◽  
Pascal-M. Aggensteiner ◽  
Martin Holtmann ◽  
Andreas Fallgatter ◽  
Marcel Romanos ◽  
...  
Keyword(s):  
Data Quality ◽  
Large Scale ◽  
Linear Models ◽  
Spectral Power ◽  
Control Group ◽  
Continuous Performance Task ◽  
Related Data ◽  
Eyes Closed ◽  
Eeg Data ◽  
Eyes Open

Electroencephalography (EEG) represents a widely established method for assessing altered and typically developing brain function. However, systematic studies on EEG data quality, its correlates, and consequences are scarce. To address this research gap, the current study focused on the percentage of artifact-free segments after standard EEG pre-processing as a data quality index. We analyzed participant-related and methodological influences, and validity by replicating landmark EEG effects. Further, effects of data quality on spectral power analyses beyond participant-related characteristics were explored. EEG data from a multicenter ADHD-cohort (age range 6 to 45 years), and a non-ADHD school-age control group were analyzed (ntotal = 305). Resting-state data during eyes open, and eyes closed conditions, and task-related data during a cued Continuous Performance Task (CPT) were collected. After pre-processing, general linear models, and stepwise regression models were fitted to the data. We found that EEG data quality was strongly related to demographic characteristics, but not to methodological factors. We were able to replicate maturational, task, and ADHD effects reported in the EEG literature, establishing a link with EEG-landmark effects. Furthermore, we showed that poor data quality significantly increases spectral power beyond effects of maturation and symptom severity. Taken together, the current results indicate that with a careful design and systematic quality control, informative large-scale multicenter trials characterizing neurophysiological mechanisms in neurodevelopmental disorders across the lifespan are feasible. Nevertheless, results are restricted to the limitations reported. Future work will clarify predictive value.

Surface height effects on postural control: A hypothesis for a stiffness strategy for stance*

1999 ◽  
Vol 9 (4) ◽  
pp. 277-286 ◽  
Author(s):  
Mark G. Carpenter ◽  
James S. Frank ◽  
Cathy P. Silcher
Keyword(s):  
Postural Control ◽  
Center Of Pressure ◽  
High Surface ◽  
Quiet Standing ◽  
Vestibular Input ◽  
Mean Power ◽  
Mean Power Frequency ◽  
Balance Confidence ◽  
Eyes Closed ◽  
Ankle Stiffness

One possible factor influencing the control of upright stance is the perceived threat to one's personal safety, i.e. balance confidence. We explored this factor by examining the control of stationary stance when standing on an elevated platform under various conditions of reduced visual and vestibular inputs. Twenty-eight adults (14 male and 14 female, mean age = 23.5 years) participated in the experiment. Postural control was examined by recording the amplitude variability (RMS) and mean power frequency (MPF) of center of pressure excursions (COP) over a 2-minute interval while participants stood in a normal stance on a low (0.19 m) and a high (0.81 m) platform with toes positioned either at or away from the edge of the platform. Vision was manipulated through eyes open and eyes closed trials. Vestibular input was reduced by tilting the head into extension [1]. Anterior-posterior RMS and MPF of COP were significantly influenced by an interaction between surface height and vision. When vision was available, a significant decrease in RMS was observed during quiet standing on a high surface compared to a low surface independent of step restriction. When vision was available MPF increased when subjects were raised from a low to a high surface. The mean position of the COP was significantly influenced by an interaction between height and step restriction. Differences in RMS and MPF responses to height manipulation were observed between genders in eyes closed conditions. Vestibular input influenced postural control at both low and high levels with significant increases in RMS when vestibular input was reduced. The reciprocal changes observed in RMS and MPF suggest modifications to postural control through changes in ankle stiffness. Vision appears to play a role in increasing ankle stiffness when balance confidence is compromised.

Effects of hypothermic anesthesia of the feet on vibration-induced body sway and adaptation

2003 ◽  
Vol 13 (1) ◽  
pp. 39-52 ◽  
Author(s):  
F. Stål ◽  
P.A. Fransson ◽  
M. Magnusson ◽  
M. Karlberg
Keyword(s):  
Postural Control ◽  
Sensory Loss ◽  
Body Sway ◽  
Cutaneous Mechanoreceptors ◽  
Supporting Surface ◽  
Eyes Closed ◽  
Somatosensory Input ◽  
Eyes Open ◽  
Sensor Information ◽  
Ice Water

The aim of this study was to investigate the significance of information from the plantar cutaneous mechanoreceptors in postural control and whether postural control could compensate for reduced cutaneous information by adaptation. Sixteen healthy subjects were tested with eyes open or eyes closed with hypothermic and normal feet temperature during posturography where body sway was induced by vibratory proprioceptive stimulation towards both calf muscles. The hypothermic anesthesia was obtained by cooling the subject's feet in ice water for 20 minutes. Body movements were evaluated by analyzing the anteroposterior and lateral torques induced towards the supporting surface by a force platform during the posturography tests. The reduction of cutaneous sensor information from the mechanoreceptors of the feet significantly increased the vibration-induced torque variance mainly in the anteroposterior direction. However, the effects of disturbed mechanoreceptors information was rapidly compensated for through postural adaptation and torque variance was in level with that without anesthesia within 50 to 100 seconds of stimulation, both when standing with eyes open and eyes closed. Our findings suggest that somatosensory input from mechanoreceptors in the foot soles contribute significantly in maintaining postural control, but the sensory loss could be compensated for.

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