Virtual-Reality-Induced Visual Perturbations Impact Postural Control System Behavior

Background: Virtual reality (VR) is becoming a widespread tool in rehabilitation, especially for postural stability. However, the impact of using VR in a “moving wall paradigm” (visual perturbation), specifically without and with anticipation of the perturbation, is unknown. Methods: Nineteen healthy subjects performed three trials of static balance testing on a force plate under three different conditions: baseline (no perturbation), unexpected VR perturbation, and expected VR perturbation. The statistical analysis consisted of a 1 × 3 repeated-measures ANOVA to test for differences in the center of pressure (COP) displacement, 95% ellipsoid area, and COP sway velocity. Results: The expected perturbation rendered significantly lower (p < 0.05) COP displacements and 95% ellipsoid area compared to the unexpected condition. A significantly higher (p < 0.05) sway velocity was also observed in the expected condition compared to the unexpected condition. Conclusions: Postural stability was lowered during unexpected visual perturbations compared to both during baseline and during expected visual perturbations, suggesting that conflicting visual feedback induced postural instability due to compensatory postural responses. However, during expected visual perturbations, significantly lowered postural sway displacement and area were achieved by increasing the sway velocity, suggesting the occurrence of postural behavior due to anticipatory postural responses. Finally, the study also concluded that VR could be used to induce different postural responses by providing visual perturbations to the postural control system, which can subsequently be used as an effective and low-cost tool for postural stability training and rehabilitation.

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Impact of Virtual Reality–Generated Construction Environments at Different Heights on Postural Stability and Fall Risk

Workplace Health & Safety ◽

10.1177/2165079920934000 ◽

2020 ◽

Vol 69 (1) ◽

pp. 32-40 ◽

Cited By ~ 1

Author(s):

Harish Chander ◽

Alireza Shojaei ◽

Shuchisnigdha Deb ◽

Sachini N. K. Kodithuwakku Arachchige ◽

Christopher Hudson ◽

...

Keyword(s):

Virtual Reality ◽

Repeated Measures ◽

Postural Stability ◽

Postural Sway ◽

Center Of Pressure ◽

Postural Instability ◽

Postural Control System ◽

Environment Exposure ◽

Acute And Chronic Exposure ◽

The Impact

Background Falls due to postural instability are common in construction environments especially from a height. The purpose of the study was to investigate the impact of virtual reality (VR)-generated environments at different virtual heights on postural stability. Methods Nineteen adults were analyzed for postural stability, tested in real (No VR) environment and in three VR environments, randomly assigned, at virtual heights of 0 ft. (VR0), 40 ft. (VR40), and 120 ft. (VR120). Postural stability was quantified using center of pressure postural sway variables and analyzed using a repeated measures analysis of variance (ANOVA). Participants also completed a simulation sickness questionnaire (SSQ) before and after VR exposure and a presence questionnaire (PQ) after VR exposure. Findings Significant postural instability ( p < .05) was identified between VR and No VR, in which increased postural instability was evident in all VR conditions compared with No VR. Scores from SSQ were within a pre–post score difference of five and the PQ score was (104.21 ± 14.03). Conclusion/Application to Practice Findings suggest that VR environments, regardless of virtual height, induced increased postural instability, which can be attributed to visual sensory conflicts to the postural control system created by VR exposure. Participants’ subjective responses on SSQ and PQ confirmed the feasibility of using VR to represent realistic immersions in virtual heights. However, objectively, VR could potentially lead to postural instability, stressing caution. VR can be a potential tool for providing virtual high-altitude environment exposure for fall prevention training, however, more research is needed on postural adaptation with acute and chronic exposure to VR.

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Center-of-Pressure Parameters Used in the Assessment of Postural Control

Journal of Sport Rehabilitation ◽

10.1123/jsr.11.1.51 ◽

2002 ◽

Vol 11 (1) ◽

pp. 51-66 ◽

Cited By ~ 176

Author(s):

Riann M. Palmieri ◽

Christopher D. Ingersoll ◽

Marcus B. Stone ◽

B. Andrew Krause

Keyword(s):

Control System ◽

Postural Control ◽

Postural Sway ◽

Center Of Pressure ◽

Data Sources ◽

Postural Control System ◽

Type Data

Objective:To define the numerous center-of-pressure derivatives used in the assessment of postural control and discuss what value each might provide in the assessment of balance.Data Sources:MEDLINE and SPORTDiscus were searched with the termsbalance, postural control, postural sway,andcenter of pressure. The remaining citations were collected from references of similar papers. A total of 67 references were studied.Conclusions:Understanding what is represented by each parameter used to assess postural control is crucial. At the present time the literature has failed to demonstrate how the variables reflect changes made by the postural-control system. Until it can be shown that the center of pressure and its derivatives actually reveal changes in the postural-control system, the value of using these measures to assess deficits in postural control is minimized.

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Characteristics of Standing Postural Control in Women under Additional Load

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17020490 ◽

2020 ◽

Vol 17 (2) ◽

pp. 490

Author(s):

Bożena Wojciechowska-Maszkowska ◽

Dorota Borzucka

Keyword(s):

Postural Control ◽

Postural Stability ◽

Postural Sway ◽

Center Of Pressure ◽

Stability Control ◽

Standing Posture ◽

Additional Load ◽

Eyes Open ◽

Heavy Loads ◽

Load Conditions

The aim of this study was to evaluate the effect of additional load on postural-stability control in young women. To evaluate postural control in the 34 women in this study (mean age, 20.8 years), we measured postural sway (center of pressure, COP) in a neutral stance (with eyes open) in three trials of 30 s each. Three load conditions were used in the study: 0, 14, and 30 kg. In analysis, we used three COP parameters, variability (linear), mean sway velocity (linear), and entropy (nonlinear). Results suggested that a considerable load on a young woman’s body (approximately 48% of body weight) had significant influence on stability. Specifically, heavy loads triggered random movements, increased the dynamics of postural-stability control, and required more attention to control standing posture. The results of our study indicate that inferior postural control mainly results from insufficient experience in lifting such a load.

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The Effects of Active Self-Correction on Postural Control in Girls with Adolescent Idiopathic Scoliosis: The Role of an Additional Mental Task

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17051640 ◽

2020 ◽

Vol 17 (5) ◽

pp. 1640 ◽

Cited By ~ 1

Author(s):

Elżbieta Piątek ◽

Michał Kuczyński ◽

Bożena Ostrowska

Keyword(s):

Adolescent Idiopathic Scoliosis ◽

Idiopathic Scoliosis ◽

Postural Control ◽

Repeated Measures ◽

Postural Sway ◽

Center Of Pressure ◽

Force Plate ◽

Stroop Test ◽

Quiet Standing ◽

Mental Task

Due to balance deficits that accompany adolescent idiopathic scoliosis (AIS), the potential interaction between activities of daily living and active self-correction movements (ASC) on postural control deserves particular attention. Our purpose was to assess the effects of ASC movements with or without a secondary mental task on postural control in twenty-five girls with AIS. It is a quasi-experimental within-subject design with repeated measures ANOVA. They were measured in four 20-s quiet standing trials on a force plate: no task, ASC, Stroop test, and both. Based on the center-of-pressure (COP) recordings, the COP parameters were computed. The ASC alone had no effect on any of the postural sway measures. Stroop test alone decreased COP speed and increased COP entropy. Performing the ASC movements and Stroop test together increased the COP speed and decreased COP entropy as compared to the baseline data. In conclusion, our results indicate that AIS did not interfere with postural control. The effects of the Stroop test accounted for good capacity of subjects with AIS to take advantage of distracting attentional resources from the posture. However, performing both tasks together exhibited some deficits in postural control, which may suggest the need for therapeutic consultation while engaging in more demanding activities.

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Postural Stability in Obese Preoperative Bariatric Patients Using Static and Dynamic Evaluation

Obesity Facts ◽

10.1159/000509163 ◽

2020 ◽

Vol 13 (5) ◽

pp. 499-513

Author(s):

Gabriel M. Pagnotti ◽

Amna Haider ◽

Ariel Yang ◽

Kathryn E. Cottell ◽

Catherine M. Tuppo ◽

...

Keyword(s):

Postural Stability ◽

Postural Sway ◽

Center Of Pressure ◽

Postural Instability ◽

Patient Specific ◽

Morbidly Obese ◽

Tissue Quality ◽

Eyes Closed ◽

Obese Subjects ◽

The Impact

Introduction: Globally, 300 million adults have clinical obesity. Heightened adiposity and inadequate musculature secondary to obesity alter bipedal stance and gait, diminish musculoskeletal tissue quality, and compromise neuromuscular feedback; these physiological changes alter stability and increase injury risk from falls. Studies in the field focus on obese patients across a broad range of body mass indices (BMI >30 kg/m2) but without isolating the most morbidly obese subset (BMI ≥40 kg/m2). We investigated the impact of obesity in perturbing postural stability in morbidly obese subjects elected for bariatric intervention, harboring a higher-spectrum BMI. Subjects and Methods: Traditional force plate measurements and stabilograms are gold standards employed when measuring center of pressure (COP) and postural sway. To quantify the extent of postural instability in subjects with obesity before bariatric surgery, we assessed 17 obese subjects with an average BMI of 40 kg/m2 in contrast to 13 nonobese subjects with an average BMI of 30 kg/m2. COP and postural sway were measured from static and dynamic tasks. Involuntary movements were measured when patients performed static stances, with eyes either opened or closed. Two additional voluntary movements were measured when subjects performed dynamic, upper torso tasks with eyes opened. Results: Mean body weight was 85% (p < 0.001) greater in obese than nonobese subjects. Following static balance assessments, we observed greater sway displacement in the anteroposterior (AP) direction in obese subjects with eyes open (87%, p < 0.002) and eyes closed (76%, p = 0.04) versus nonobese subjects. Obese subjects also exhibited a higher COP velocity in static tests when subjects’ eyes were open (47%, p = 0.04). Dynamic tests demonstrated no differences between groups in sway displacement in either direction; however, COP velocity in the mediolateral (ML) direction was reduced (31%, p < 0.02) in obese subjects while voluntarily swaying in the AP direction, but increased in the same cohort when swaying in the ML direction (40%, p < 0.04). Discussion and Conclusion: Importantly, these data highlight obesity’s contribution towards increased postural instability. Obese subjects exhibited greater COP displacement at higher AP velocities versus nonobese subjects, suggesting that clinically obese individuals show greater instability than nonobese subjects. Identifying factors contributory to instability could encourage patient-specific physical therapies and presurgical measures to mitigate instability and monitor postsurgical balance improvements.

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Effect of Cardiovascular Fatigue on Postural Stability

International Journal of Athletic Therapy & Training ◽

10.1123/ijatt.18.5.38 ◽

2013 ◽

Vol 18 (5) ◽

pp. 38-40 ◽

Cited By ~ 1

Author(s):

Hamid Bateni ◽

Gina Leno ◽

Rebeca Manjarres ◽

Bailey Ouellette ◽

Mark Wolber

Keyword(s):

Outcome Measures ◽

Repeated Measures ◽

Postural Stability ◽

Postural Sway ◽

Center Of Pressure ◽

Standing Position ◽

Treadmill Running ◽

Upper Body ◽

Mean Square Distance ◽

Squat Jumps

Context:Previous research has demonstrated that localized leg muscle fatigue induced by lower extremity exercises (e.g., squat jumps, sprints, and treadmill running) has an adverse effect on postural stability.Objective:To assess the effect of cardiovascular fatigue induced by upper extremity exercise on postural stability.Design:Repeated measures.Participants:Fourteen healthy young adults between the ages of 22 and 30 years (7 male and 7 female).Intervention:Participants performed an exercise protocol on an upper-body ergometer to induce cardiovascular fatigue.Main Outcome Measures:Postural sway, represented by center of pressure excursion, during bilateral standing in two different foot positions.Results:In a tandem standing position, mediolateral mean distance, root mean square distance, resultant power, and centroidal frequency increased signifcantly after inducement of cardiovascular fatigue.Conclusion:Cardiovascular fatigue adversely affects postural stability.

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Center of pressure-based postural sway differences on parallel and single leg stance in Olympic deaf basketball and volleyball players

Journal of Exercise Rehabilitation ◽

10.12965/jer.2142558.279 ◽

2021 ◽

Vol 17 (6) ◽

pp. 418-427

Author(s):

Yücel Makaracı ◽

Recep Soslu ◽

Ömer Özer ◽

Abdullah Uysal

Keyword(s):

Postural Control ◽

Postural Stability ◽

Postural Sway ◽

Center Of Pressure ◽

Force Plate ◽

Basketball Players ◽

Male Athletes ◽

Significant Difference ◽

Single Leg Stance ◽

Volleyball Players

In sports such as basketball and volleyball, loss of balance due to the inability to maintain body stability and lack of postural control adversely affect athletic performance. Deaf athletes appear to struggle with balance and postural stability problems. The purpose of this study was to examine postural sway values in parallel and single leg stance of Olympic deaf basketball and volleyball players and reveal differences between the branches. Twenty-three male athletes from the Turkish national deaf basketball (n= 11) and volleyball (n= 12) teams participated in the study. After anthropometric measurements, the subjects completed postural sway (PS) tests in parallel/single leg stances with open eyes and closed eyes on a force plate. PS parameters (sway path, velocity, and area) obtained from the device software were used for the statistical analysis. The Mann-Whitney U-test was used to compare differences in PS parameters between basketball and volleyball players, and the alpha value was accepted as 0.05. Volleyball players had significantly better results in parallel stance and dominant leg PS values than basketball players (P<0.05). There was no significant difference between the groups in nondominant leg PS values (P>0.05). We think that proprioceptive and vestibular system enhancing training practices to be performed with stability exercises will be beneficial in terms of both promoting functional stability and interlimb coordination. Trainers and strength coaches should be aware of differences in the postural control mechanism of deaf athletes.

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Changed Temporal Structure of Neuromuscular Control, Rather Than Changed Intersegment Coordination, Explains Altered Stabilographic Regularity after a Moderate Perturbation of the Postural Control System

Entropy ◽

10.3390/e21060614 ◽

2019 ◽

Vol 21 (6) ◽

pp. 614 ◽

Cited By ~ 4

Author(s):

Felix Wachholz ◽

Tove Kockum ◽

Thomas Haid ◽

Peter Federolf

Keyword(s):

Control System ◽

Postural Control ◽

Center Of Pressure ◽

Temporal Structure ◽

Force Plate ◽

Principal Component ◽

Neuromuscular Control ◽

Postural Control System ◽

Temporal Regularity ◽

Postural Movement

Sample entropy (SaEn) applied on center-of-pressure (COP) data provides a measure for the regularity of human postural control. Two mechanisms could contribute to altered COP regularity: first, an altered temporal structure (temporal regularity) of postural movements (H1); or second, altered coordination between segment movements (coordinative complexity; H2). The current study used rapid, voluntary head-shaking to perturb the postural control system, thus producing changes in COP regularity, to then assess the two hypotheses. Sixteen healthy participants (age 26.5 ± 3.5; seven females), whose postural movements were tracked via 39 reflective markers, performed trials in which they first stood quietly on a force plate for 30 s, then shook their head for 10 s, finally stood quietly for another 90 s. A principal component analysis (PCA) performed on the kinematic data extracted the main postural movement components. Temporal regularity was determined by calculating SaEn on the time series of these movement components. Coordinative complexity was determined by assessing the relative explained variance of the first five components. H1 was supported, but H2 was not. These results suggest that moderate perturbations of the postural control system produce altered temporal structures of the main postural movement components, but do not necessarily change the coordinative structure of intersegment movements.

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AGE-RELATED CHANGES IN POSTURAL RE-BALANCED ABILITY DURING A CONTINUOUS AND UNEXPECTED PERTURBATION INTEGRATED WITH VIRTUAL REALITY SCENES

Biomedical Engineering Applications Basis and Communications ◽

10.4015/s1016237216500204 ◽

2016 ◽

Vol 28 (03) ◽

pp. 1650020

Author(s):

Chun-Ju Chang ◽

Jen-Suh Chern ◽

Tsui-Fen Yang ◽

Sai-Wei Yang

Keyword(s):

Virtual Reality ◽

Postural Control ◽

Postural Stability ◽

Center Of Pressure ◽

Random Sequence ◽

Weight Bearing ◽

The Body ◽

Assessment Protocol ◽

Healthy Elderly ◽

Age Related

The degeneration of sensory and motor systems due to aging could affect the elderly’s posture and increase the risk of falling. The strategies applied to maintain postural stability might be different between ages, especially in the condition requiring both proprioception and vision sensorimotor coupling. This study proposed a novel sensorimotor assessment protocol to evaluate the postural control ability across the aging process, by using the computerized dynamic posturography and the virtual reality (VR) system. Ten young and 20 elderly healthy adults without fall experience were recruited, and were assessed on a continuous-perturbed platform with or without the VR-based visual interference in a random sequence. Measured variables of the center of pressure as well as the weight-bearing ratio were analyzed and compared. Results showed that the postural sway was significantly larger in all subjects under the VR condition, but the young subjects could rapidly adjust the body to regain postural stability in a rhythmic and symmetric manner; whereas, the elderly adults performed less effectively in postural response. We suggested that the application of the multiple sensation disturbances with VR could effectively evaluate the postural control ability among the healthy elderly. The proposed assessing protocol is also recommended for training the sensorimotor integration to improve the dynamic postural control ability.

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Functional Task Constraints Foster Enhanced Postural Control in Children With Cerebral Palsy

Physical Therapy ◽

10.2522/ptj.20140425 ◽

2016 ◽

Vol 96 (3) ◽

pp. 348-354 ◽

Cited By ~ 8

Author(s):

Jennifer M. Schmit ◽

Michael Riley ◽

Sarah Cummins-Sebree ◽

Laura Schmitt ◽

Kevin Shockley

Keyword(s):

Cerebral Palsy ◽

Postural Control ◽

Postural Stability ◽

Postural Sway ◽

Postural Instability ◽

Apparent Difference ◽

Typical Development ◽

Postural Control System ◽

Study Objective ◽

Functional Play

BackgroundPostural instability is a classical characteristic of cerebral palsy (CP), but it has not been examined during functional play activity. Recent work has demonstrated that when motor tasks are made functionally more relevant, performance improves, even in children with movement pathology. It is possible that in a disease state, the underlying control mechanisms that are associated with healthy physiology must be elicited.ObjectiveThe study objective was to explore the utility of the functional play task methodology as a more rich and interpretable approach to the quantification of postural instability in children with CP.DesignPostural stability measures obtained from a cross-sectional cohort of children with CP (n=30) were compared with stability measures taken from children with typical development (n=30) during a single measurement period.MethodsPostural stability data were obtained with a portable force platform system. Postural sway was quantified during a precision manual functional play task. A baseline condition (no task) also was included. Postural sway variability and postural sway regularity were analyzed with analyses of variance.ResultsThere was an apparent difference in postural control (greater irregularity, greater sway variability) during quiet stance between children with CP and peers with typical development; this difference was mitigated during the performance of the precision functional play task.LimitationsA small and nonprobability sample of convenience may limit the findings of this study.ConclusionsThe findings illustrate flexibility and adaptability in the postural control system despite the pathological features associated with CP.

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