Postural Control In Healthy Adults Research Articles

Investigating Eye Movement and Postural Stability Relationships Using Mobile Eye-Tracking and Posturography: A Cross-Sectional Study.

Vision and eye movements play a crucial role in maintaining postural stability. This study investigated the relationship between eye movements and postural control in healthy adults using mobile eye-tracking technology and posturography. Forty healthy participants underwent assessments of eye movements using a mobile eye-tracking system and postural stability using Tetrax posturography under various sensory conditions. Pearson correlation coefficients were computed to examine associations between eye movement parameters and postural control indices. Significant correlations were found between eye movement parameters and postural stability indices. Faster and more consistent horizontal eye movements were associated with better postural stability (r = -0.63, p < 0.05). Eye movement speed variability positively correlated with weight distribution indices under normal eyes open (r = 0.65, p < 0.05) and closed (r = 0.59, p < 0.05) conditions. Coordination of horizontal and vertical eye movements positively correlated with postural control (r = 0.69, p < 0.01). Negative correlations were observed between eye movement coordination and Fourier indices in various frequency bands (p < 0.05) and the stability index under different head positions (p < 0.05). The findings provide insights into sensory integration mechanisms underlying balance maintenance and highlight the importance of integrated sensory processing in postural stability. Eye movement assessments have potential applications in balance evaluation and fall risk prediction.

Effect of Annoying Sounds on Postural Control.

Objectives: This study aimed to explore the impact of irritating sounds on the postural control of healthy adults, considering both linear and nonlinear parameters, subjective assessments, and gender differences. Methods: Thirty-four young participants (17 females, 17 males) completed three 30 s bipedal standing stability tests on a balance platform: one with visual control (EO), another without visual control (EC), and a third without visual control but accompanied by irritating sounds (ECS). Additionally, participants filled out a questionnaire evaluating their sound sensitivity. Linear and nonlinear parameters from each balance test were considered for statistical analysis. Results: The findings reveal significant gender-based variations in sensitivity to sound, with women exhibiting higher sensitivity. No statistically significant differences in postural control were observed between males and females, except for a notable increase in irregularity (SampEn values) in the anterior-posterior direction for females in the ECS trial. Correlation analyses revealed a moderate and statistically significant correlation between SampEn values in the AP direction and SE scores. Conclusions: This study highlights the intricate relationship between sensory stimuli, attention, and the body's ability to maintain balance. The presence of irritating sounds led to increased irregularity in postural control, particularly in the absence of visual control.

A Study Protocol to Evaluate the Effects of Vestibular Training on the Postural Control of Healthy Adults Using Virtual Reality

Postural instability is a common symptom of vestibular dysfunction due to an insult to the vestibular system. Vestibular rehabilitation is effective in decreasing dizziness and visual symptoms, and improving postural control through several mechanisms, including sensory reweighting. As part of the sensory reweighting mechanisms, vestibular activation training with headshake activities influences vestibular reflexes. However, combining challenging vestibular and postural tasks to facilitate more effective rehabilitation outcomes is underutilized. Our research goal is to develop a virtual reality vestibular rehabilitation method for vestibular-postural control in neurological populations with vestibular and/or sensorimotor control impairment. The NeuroCom® SMART Balance Master (Natus Medical Inc., Pleasanton, CA, USA), which was used in a prior study, is expensive and bulky. Hence, a novel study protocol is established in this paper with the detailed objectives and pre-/post-intervention data analysis pipeline (ANOVA, t-test, post hoc analysis, etc.) involving modern off-the-shelf sensors and custom instrumentation (electromyography, electrooculography, video head impulse testing, force plates, and virtual reality headsets). It is expected that the training will significantly decrease vestibuloocular reflex gains and eye movement variability, as well as reweight the somatosensory ratio, finetune postural muscle activation, and consequently improve postural flexibility and produce a faster automatic postural response. The findings may have implications for the future development of vestibular rehabilitation protocols.

The Correlation between Proprioception and Postural Control in Healthy Adults.

The Article’s Abstract is not available.

The Effect of Transcutaneous Spinal Cord Stimulation on Standing Postural Control in Healthy Adults

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Aim:</i> To determine the effects of pulsed current transcutaneous spinal cord stimulation (TSCS) on both the spinal circuitry and the neuromotor response observed after a trunk force perturbation. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Methods:</i> A group of young healthy adults performed two experiments to study the effects of TSCS. In experiment I, the effect of TSCS on the spinal circuitry was assessed using the Hoffman-reflex (H-reflex) recruitment curve and recovery cycle. In Experiment II, the effect of TSCS on the response to trunk force perturbation was assessed with both stimulation on and off. The force perturbations were delivered by the robotic upright trunk support trainer (RobUST). <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Results:</i> 30 Hz monophasic pulsed current TSCS induced spinal plasticity and increased spinal excitability. This TSCS protocol also increased muscle activation in response to specific pelvic force perturbations. These results suggest that TSCS can modulate the integration of voluntary descending commands and sensory signals and alter muscle activation during a postural task, even in neurologically intact subjects. We plan to use these results to develop training protocols to improve balance during standing in patients with spinal cord injury (SCI).

Stationary auditory white noise improves postural control in healthy adults: A novel study on head-shaking.

Auditory cues might play a role in postural control. The primary aim of this study was to investigate the association between white noise and head-shake (HS) related changes in postural sway. Fifty healthy adults underwent Synapsys Posturography System (SPS) evaluation. The posturography (PG) evaluation consisted of two protocols: sensory organization test (SOT) and SOT with head-shake (HS) (HS-SOT). The standard SOT protocol of SPS involves a battery of six postural conditions. In the current study, participants underwent only four SOT conditions. The participants were asked to stand barefoot on the SPS platform (static platform and foam). The SOT standing conditions were as follow: (1) firm surface (force platform only) with eyes open (SOT1); (2) firm surface with eyes closed (SOT2); (3) foam surface (which was positioned on the force platform) with eyes open (SOT4); and (4) foam surface with eyes closed (SOT5). For the HS-SOT protocol, we asked the participants to move their heads left and right (i.e., yaw head rotation) in the mentioned SOT conditions. Each postural condition was 10 seconds long. Both SOT and HS-SOT postural conditions were conducted across the two hearing modes of silence and noise. To achieve our aims, comparison of sway parameters between SOT and HS-SOT, and between hearing modes were considered. White noise was associated with a reduction in postural sway. The reduction observed in sway area, sway amplitude, and sway frequency. Moreover, HS significantly increased postural sway in all HS-SOT conditions compared to their SOT equivalents (i.e., HS-SOT1 compared to SOT1, etc.). The presence of white noise was associated with a decrease in the HS-related increase in postural sway. Considering the results, this study adds to the body of literature suggesting that white noise contributes to postural control, and the implications of this for rehabilitation need to be further investigated.

Using nonlinear measures to evaluate postural control in healthy adults during bipedal standing on an unstable surface

Purpose: This study examined the use of nonlinear measures – sample entropy (SampEn), fractal dimension (FD), and the Lyapunov exponent (LyE) – to evaluate postural control in adults during standing on an unstable surface, with and without visual feedback. Methods: 14 healthy young adults (24.07 ± 7.32 years) completed bipedal standing trials on an unstable-plate Biodex Balance System (BBS) connected to a Vicon system, with eyes open and closed. Each trial lasted 20 sec. Analysis was performed based on the center of mass (CoM), for which the three nonlinear measures were calculated. Results: Excluding visual feedback was found to cause a significant increase in linear and nonlinear parameters. Moreover, SampEn and FD values were found to be significantly higher in the PD direction, compared to AP or ML, whereas LyE values in this direction were minimal. Conclusions: Results show that the three nonlinear measures provide a useful way of evaluating postural control in healthy adults. Moreover, it seems that introducing an unstable surface meant that the projection of the CoM was not perpendicular to the surface, but rather set at a certain continually changing angle, forcing the whole system to adapt to chaotic and unpredictable conditions. Such refined changes in conditions can be evaluated in a precise way only by using nonlinear measures.

Rating of perceived exertion (RPE) in studies of fatigue-induced postural control alterations in healthy adults: Scoping review of quantitative evidence.

Amongst the literature researching the effects of exercise-induced fatigue on postural control in healthy adults, many studies have used the Borg scales to document the rating of perceived exertion (RPE) and have shown a broad range of RPE values. Our main aim was to map fatigue-induced RPE values in included publications. Secondary aims were to summarize the preference and purpose for the use of Borg scales within the included publications and to explore the potential associations between fatigue-induced RPE values and postural control changes. Five databases (Ovid Medline, PubMed, CINAHL, Scopus, and SPORTDiscus) were systematically searched for synthesizing data among the publications that reported RPE values on the Borg RPE- and Category-Ratio (CR) 10 scales and also found fatigue effects on postural control in healthy adults. Spearman's rank correlations were conducted to assess potential associations between fatigue-induced RPE values and maximal postural control changes across the included publications (group data). 45 of 51 studies included in this review reported maximal RPE values following exercise and ranged from 10.4-20 (6-20 Borg RPE) or 0.9-10 (CR10) indicating "very light" or "very weak" to "maximal" exertions. The 6-20 Borg and CR10 scales were mainly used to assess cardiovascular and muscular exertion, respectively. The scales were used mostly to estimate fatigue levels (n = 45), and to a lesser extent to produce a specific exercise intensity (n = 5) and as the criterion for exercise termination (n = 1). In general, there was no significant association between RPE and postural control changes across studies. The broad range of RPE values and weak correlations may suggest that various fatigue levels can lead to postural control changes. However, one should be careful in comparing the extent of fatigue from RPE values and its potential effect on postural control in the light of many confounding factors.

Effects of Vestibular Training on Postural Control of Healthy Adults

Background: Postural stability depends on the integration of multisensory inputs to drive motor outputs. When visual and somatosensory input is available and reliable, this reduces the postural control system’s reliance on the vestibular system. Despite this, vestibular loss can still cause severe postural dysfunction (1,2). Training one or more of the three sensory systems can alter sensory weighting and change postural behavior. Vestibular activation exercises, including horizontal and vertical headshaking, influence vestibular-ocular and -motor responses and have been showed to be effective in vestibular rehabilitation (3–8). &#x0D; Purpose/Hypothesis: To assess sensory reweighting of postural control processing and vestibular-ocular and -motor responses after concurrent vestibular activation with postural training. It was hypothesized that the effect of this training would significantly alter the pattern of sensory weighting by changing the ratio of visual, somatosensory and vestibular dependence needed to maintain postural stability, and significantly decrease vestibular responses.&#x0D; Methods: Forty-two young healthy individuals (22 females; 23.0+3.9 years; 1.6+0.1 meters) were randomly assigned into four groups: 1) visual feedback weight shift training (WST) coupled with an active horizontal headshake (HHS), 2) same WST with vertical headshake (VHS), 3) WST with no headshake (NHS) and 4) no training/headshake control (CTL) groups. The headshake groups performed an intensive body WST together with horizontal or vertical rhythmic headshake at 80 to 120 beats/minute. The NHS group performed the WST with no headshake while the controls did not perform any training. Five 15-minute training sessions were performed on consecutive days for one week with the weight shift exercises involving upright limits of stability activities on a flat surface, foam or rocker board (Fig. 1). All groups performed baseline- and post-assessments including sensory organization test (SOT) and force platform ramp perturbations, coupled with electromyographic (EMG) recordings. A video head impulse test was also used to record horizontal vestibulo-ocular reflex (VOR) gain. A between- and within-group repeated measures ANOVA was used to analyze five COP sway variables, the equilibrium and composite scores and sensory ratios of the SOT as well as EMG signals and horizontal VOR gain. Similarly, COP variables, EMG, as well as vestibular reflex data (vertical VOR, vestibulo-collic reflex [VCR] and vestibulo-spinal [VSR] gains) during ramp perturbations were analyzed. Alpha level was set at p&lt;.05.&#x0D; Results: The training showed a significant somatosensory downweighting (p=.050) in the headshake groups compared to the other groups. Training also showed significant decreased horizontal VOR gain (p=.040), faster automatic postural response (p=.003) (Figs. 2-4) with improved flexibility (p=.010) in the headshake groups. Muscle activation pattern in medial gastrocnemius (p=.033) was significantly decreased in the headshake.&#x0D; Conclusion: The concurrent vestibular activation and weight shift training modifies vestibular-dependent responses after the training intervention as evidenced in somatosensory downweighting, decreased VOR gain, better postural flexibility and faster automatic postural response. Findings suggest this is predominantly due to vestibular adaptation and habituation of VOR, VCR and VSR which induced sensory reweighting.&#x0D; Clinical relevance: Findings may be used to guide the development of a vestibular-postural rehabilitation intervention in impaired neurological populations, such as with vestibular disorders or sensory integration problems.

The effect of virtual reality-based balance training on motor learning and postural control in healthy adults: a randomized preliminary study

BackgroundAdults with sedentary lifestyles seem to face a higher risk of falling in their later years. Several causes, such as impairment of strength, coordination, and cognitive function, influence worsening health conditions, including balancing ability. Many modalities can be applied to improve the balance function and prevent falling. Several studies have also recorded the effects of balance training in elderly adults for fall prevention. Accordingly, the aim of this study is to define the effect of virtual reality-based balance training on motor learning and postural control abilities in healthy adults.MethodsFor this study, ten subjects were randomly allocated into either the conventional exercise (CON) or the virtual reality (VR) group. The CON group underwent physical balance training, while the VR group used the virtual reality system 4 weeks. In the VR group, the scores from three game modes were utilized to describe the effect of motor learning and define the learning curves that were derived with the power law function. Wilcoxon Signed Ranks Test was performed to analyze the postural control in five standing tasks, and data were collected with the help of a force plate.ResultsThe average score was used to describe the effect of motor learning by deriving the mathematical models for determining the learning curve. Additionally, the models were classified into two exponential functions that relied on the aim and requirement skills. A negative exponential function was observed in the game mode, which requires the cognitive-motor function. In contrast, a positive exponential function was found in the game with use of only the motor skill. Moreover, this curve and its model were also used to describe the effect of learning in the long term and the ratio of difficulty in each game. In the balance performance, there was a significant decrease in the center of pressure parameters in the VR group, while in the CON group, there was a significant increase in the parameters during some foot placements, especially in the medio-lateral direction.ConclusionThe proposed VR-based training relies on the effect of motor learning in long-term training though different kinds of task training. In postural analysis, both exercise programs are emphasized to improve the balance ability in healthy adults. However, the virtual reality system can promote better outcomes to improve postural control post exercising.Trial registration Retrospectively registered on 25 April 2018. Trial number TCTR20180430005

Sensory reweighting after loss of auditory cues in healthy adults

We maintain our balance using information provided by the visual, somatosensory, and vestibular systems on the position of our body in space. Recent evidence has suggested that auditory input also plays a significant role for postural control, yet further investigations are required to better understand the contributions of audition to this process in healthy adults. To date, the process of sensory reweighting when auditory cues are disturbed during postural control has been overlooked. The aim of this study is to determine the impact of hearing protection on sensory reweighting for postural control in healthy adults. For this, we studied 14 healthy adults on a force platform using four different postural conditions either with or without attenuation of auditory cues. Our results suggest that disturbing auditory cues increases the reliance on visual cues for postural control. This is the first study to demonstrate such a sensory reweighting occurs in the event of a sudden disturbance of auditory cues in healthy adults.

Test-Retest Reliability and Practice Effects of the Stability Evaluation Test.

Postural control plays an essential role in concussion evaluation. The Stability Evaluation Test (SET) aims to objectively analyze postural control by measuring sway velocity on the NeuroCom VSR portable force platform (Natus, San Carlos, CA). To assess the test-retest reliability and practice effects of the SET protocol. Cohort. Research laboratory. 50 healthy adults (20 men, 30 women, age 25.30 ± 3.60 y, height 166.60± 12.80 cm, mass 68.80 ± 13.90 kg). All participants completed 4 trials of the SET. Each trial consisted of six 20-s balance tests with eyes closed, under the following conditions: double-leg firm (DFi), single-leg firm (SFi), tandem firm (TFi), double-leg foam (DFo), single-leg foam (SFo), and tandem foam (TFo). Each trial was separated by a 5-min seated rest period. The dependent variable was sway velocity (deg/s), with lower values indicating better balance. Sway velocity was recorded for each of the 6 conditions as well as a composite score for each trial. Test-retest reliability was analyzed across 4 trials with intraclass correlation coefficients (ICCs). Practice effects analyzed with repeated measures analysis of variance, followed by Tukey post hoc comparisons for any significant main effects (P < .05). Sway-velocity reliability values were good to excellent: DFi (ICC = .88; 95%CI: .81, .92), SFi (ICC = .75; 95%CI: .61, .85), TFi (ICC = .84; 95%CI: .75, .90), DFo (ICC = .83; 95%CI: .74, .90), SFo (ICC = .82; 95%CI: .72, .89), TFo (ICC = .81; 95%CI: .69, .88), and composite score (ICC = .93; 95%CI: .88, .95). Significant practice effects (P < .05) were noted on the SFi, DFo, SFo, TFo conditions and composite scores. Our results suggest the SET has good to excellent reliability for the assessment of postural control in healthy adults. Due to the practice effects noted, a familiarization session is recommended (ie, all 6 conditions) before data are recorded. Future studies should evaluate injured patients to determine meaningful change scores during various injuries.

The influence of peripheral vision induced by moving people on postural control in healthy adults.

This study was conducted to examine the influence of the peripheral vision (PV) induced by moving people on postural control in healthy adults. The subjects consisted of 12 healthy adult volunteers (5 males, 7 females) who had been informed of the study purpose and procedure. The visual interventions were composed of three types. PV1 and PV2 were stimulated using a one-way vertical striped pattern and a two-way vertical striped pattern, respectively. To embody the features of moving people reflected in the mirrors, researchers recorded movements of people or objects provided by mirrors on video image. In this study, this was named PV3. The subjects were exposed to each of the visual stimuli for 3 min in a random order, and their postural control was then evaluated. All the subjects were allowed to practice once prior to performing the one leg stand test, functional reaching test and body sway test. All the evaluations were made before and after the visual intervention, and the subjects rested for 30 min between each intervention. PV3 ranked second in before and after differences of trace length and velocity and had no significant difference from PV2, demonstrating that the PV3, as well as PV2, affected the amount and velocity of body sway. In addition, the standard deviation velocity, trace length and velocity values of PV3 were higher than the PV1 values. Therefore, the treatment of those who have difficulty with postural control and balance maintenance should take place in a controlled therapeutic environment.

Chronic Low Quality Sleep Impairs Postural Control in Healthy Adults

The lack of sleep, both in quality and quantity, is an increasing problem in modern society, often related to workload and stress. A number of studies have addressed the effects of acute (total) sleep deprivation on postural control. However, up to date, the effects of chronic sleep deficits, either in quantity or quality, have not been analyzed. Thirty healthy adults participated in the study that consisted of registering activity with a wrist actigraph for more than a week before performing a series of postural control tests. Sleep and circadian rhythm variables were correlated and the sum of activity of the least active 5-h period, L5, a rhythm variable, obtained the greater coefficient value with sleep quality variables (wake after sleep onset WASO and efficiency sleep). Cluster analysis was performed to classify subjects into two groups based on L5 (low and high). The balance tests scores used to asses postural control were measured using Biodex Balance System and were compared between the two groups with different sleep quality. The postural tests were divided into dynamic (platform tilt with eyes open, closed and cursor) and static (clinical test of sensory integration). The results showed that during the tests with eyes closed, the group with worse sleep quality had also worse postural control performance. Lack of vision impairs postural balance more deeply in subjects with chronic sleep inefficiency. Chronic poor sleep quality impairs postural control similarly to total sleep deprivation.

Postural Control in Healthy Young Adults with and without Chronic Motion Sensitivity

Background: Postural control requires complex processing of peripheral sensory inputs from the visual, somatosensory and vestibular systems. Motion sensitivity and decreased postural control are influenced by visual-vestibular con flicts. The purpose of this study was to measure the difference between the postural control of healthy adults with and without history of sub-clinical chronic motion sensitivity using a computerized dynamic posturography in a virtual reality environment. Sub-clinical chronic motion sensitivity was operationally defined as a history of avoiding activities causing dizziness, nausea, imbalance, and/or blurred vision without having a related medical diagnosis. Methods: Twenty healthy adults between 22 and 33 years of age participated in the study. Eleven subjects had sub-clinical chronic motion sensitivity and 9 subjects did not. Postural control was measured in both groups using the Bertec Balance Advantage-Dynamic Computerized Dynamic Posturography with Immersion Virtual Reality (CDP-IVR). The CDP-IVR reports an over-all equilibrium score based on subjects’ center of gravity displacement and postural sway while immersed in a virtual reality environment. Subjects were tested on stable (condition 1) and unstable (condition 2) platform conditions. Results: There was no significant difference between the two groups in terms of mean age, height, weight, body mass index in kg/m2, postural control scores for conditions 2, and average (p>0.05). However, significant differences were observed in mean postural control for condition 1 between groups (p=0.03). Conclusions: Results of this study suggest that healthy young adults without chronic sub-clinical motion sensitivity have better postural control than those with chronic sub-clinical motion sensitivity. Further investigation is warranted to explore wider age ranges with larger samples sizes as well as intervention strategies to improve postural control.

視覚情報の位置が健常成人の立位制御に及ぼす影響

視覚情報の位置が健常成人の立位制御に及ぼす影響

Effects of age and acute muscle fatigue on reactive postural control in healthy adults

BackgroundFalls can cause moderate to severe injuries such as hip fractures and head trauma in older adults. While declines in muscle strength and sensory function contribute to increased falls in older adults, skeletal muscle fatigue is often overlooked as an additional contributor to fall risk. The purpose of this investigation was to examine the effects of acute lower extremity muscle fatigue and age on reactive postural control in healthy adults. MethodsA sample of 16 individuals participated in this study (8 healthy older adults and 8 healthy young persons). Whole body kinematic and kinetic data were collected during anterior and posterior reproducible fall tests before (T0) and immediately after (T1) eccentric muscle fatiguing exercise, as well as after 15-min (T15) and 30-min (T30) of rest. FindingsLower extremity joint kinematics of the stepping limb during the support (landing) phase of the anterior fall were significantly altered by the presence of acute muscle fatigue. Step velocity was significantly decreased during the anterior falls. Statistically significant main effects of age were found for step length in both fall directions. Effect sizes for all outcomes were small. No statistically significant interaction effects were found. InterpretationMuscle fatigue has a measurable effect on lower extremity joint kinematics during simulated falls. These alterations appear to resolve within 15min of recovery. The above deficits, coupled with a reduced step length, may help explain the increased fall risk in older adults.

Upper body balance control strategy during continuous 3D postural perturbation in young adults

We explored how changes in vision and perturbation frequency impacted upright postural control in healthy adults exposed to continuous multiaxial support-surface perturbation. Ten subjects were asked to maintain equilibrium in standing stance with eyes open (EO) and eyes closed (EC) during sinusoidal 3D rotations at 0.25 (L) and 0.50Hz (H). We measured upper-body kinematics – head, trunk, and pelvis – and analyzed differences in horizontal displacements and roll, pitch, and yaw sways. The presence of vision significantly decreased upper-body displacements in the horizontal plane, especially at the head level, while in EC the head was the most unstable segment. H trials produced a greater segment stabilization compared to L ones in EO and EC. Analysis of sways showed that in EO participants stabilized their posture by reducing the variability of trunk angles; in H trials a sway decrease for the examined segments was observed in the yaw plane and, for the pelvis only, in the pitch plane. Our results suggest that, during continuous multiaxial perturbations, visual information induced: (i) in L condition, a continuous reconfiguration of multi-body-segments orientation to follow the perturbation; (ii) in H condition, a compensation for the ongoing perturbation. These findings were not confirmed in EC where the same strategy – that is, the use of the pelvis as a reference frame for the body balance was adopted both in L and H.

Lateral ankle ligament anesthesia significantly alters single limb postural control

Lateral ankle anesthesia has been used as a model to explore effects of ligament deafferentation related to ankle sprain on single limb postural control with conflicting results. Time-to-boundary (TTB) is a postural control measurement technique found to be sensitive in detecting subtle deficits in postural control in those with chronic ankle instability. The objective of this study was to determine the effects of lateral ankle ligament anesthesia on TTB measures of single limb postural control in healthy adults. Twenty-two healthy adults with no history of lower extremity injury within the past 6 months or balance disorders participated in the study. All subjects received a lidocaine injection to the lateral ankle structures on one of two testing days. On both testing days, subjects performed 3 eyes open and 3 eyes closed, 10-s trials of barefoot single limb stance on a forceplate. The dependent variables were the mean of TTB minima(s) and standard deviation of TTB minima(s) in mediolateral (ML) and anteroposterior (AP) directions. Separate condition (anesthesia, control) by vision (eyes open, eyes closed) ANOVAs with repeated measures were used for each TTB variable to determine the effects of anesthesia on postural control. Alpha level was set a priori at p ≤ 0.05. The anesthesia day TTBAP magnitude ( p = 0.008) and variability ( p = 0.044) measures were significantly lower than the control day, regardless of vision. Anesthesia of the lateral ankle ligamentous structures significantly reduced the magnitude and variability of TTBAP measures. These findings are similar to deficits found in those with chronic ankle instability.

Hemispheric asymmetry in the visual contribution to postural control in healthy adults

This study was carried out in order to test the hypothesis of a right hemisphere dominance in the visual control of body balance. Eight healthy adults were subjected to a self-regulated lateral balance task, performed while sitting on a rocking platform. Four visual conditions were tested: open eyes with normal vision, closed eyes in the dark, left visual field-right hemisphere and right visual field-left hemisphere. Head and support displacements in the roll plane were recorded by means of an optoelectronic system. Two main results emerged from this study: (1) head stabilization in space was much more efficient in the left visual field-right hemisphere condition than in the three other visual conditions, and (2) although vision played an important role in the body stability whatever the anatomical level, there was no right hemisphere dominance at the pelvic level. A clear right hemisphere dominance was thus demonstrated as regards the visual contribution to head stabilization in space.