Postural Sway Measures Research Articles

Effects of balance training with visual input manipulations on balance performance and sensory integration in healthy young adults: a randomized controlled trial.

Although balance training can improve balance across various populations, the underlying mechanisms, such as how balance training may alter sensory integration, remain unclear. This study examined the effects of balance training with visual input manipulations provided by virtual reality versus conventional balance training on measures of postural sway and sensory integration during balance control. Twenty-two healthy young adults were randomly allocated into a balance training group (BT) or a balance training with virtual reality group (BT + VR). The BT received traditional balance training, while the BT + VR additionally received visual manipulations during the 4-week balance training to elicit sensory conflicts. Static balance was measured in the form of center of pressure (COP) sway speed in trained (eyes open) and untrained (eyes closed) balance conditions. A model-based analysis quantified the sensory integration and feedback characteristics of the balance control mechanism. Herein, the visual weight quantifies the contribution of visual orientation information to balance while the proportional and derivative feedback loop-gains correct for deviations from the desired angular position and angular velocity, respectively. Significant main time effects were observed for the visual sensory contribution to balance (p = 0.002, [Formula: see text] = 0.41) and for the derivative feedback loop-gain (p = 0.011, [Formula: see text] = 0.29). Significant group-by-time interactions were observed for COP sway speed in the untrained task (p = 0.023, [Formula: see text] = 0.23) in favor of BT + VR and in the proportional feedback loop-gain, with reductions only in the BT + VR group (p = 0.043, [Formula: see text] = 0.2). BT + VR resulted in larger performance improvements compared with traditional BT in untrained tasks, most likely due to reduced reliance on visual information. This suggests that the systematic modulation of sensory inputs leads to enhanced capacity for motor adaptation in balance training.

Graviception Uncertainty, Spatial Anxiety, and Derealization in Patients with Persistent Postural-Perceptual Dizziness.

Objectives: Persistent Postural-Perceptual Dizziness (PPPD) is a frequent diagnosis in patients with chronic dizziness, ineffective postural control, visual dependence, and emotional symptoms. Methods: 53 patients with PPPD (25-84 years old) and 53 adults (29-84 years old) with no vestibular disease agreed to participate in this study. Assessments included: vestibular function tests (sinusoidal yaw rotation and vestibular-evoked myogenic potentials); accuracy and precision of Subjective Visual Vertical (SVV) estimation while static and during on-axis yaw rotation; static posturography with open/closed eyes and 30° neck extension, while standing on hard/soft surface; questionnaires on symptoms of unsteadiness, spatial anxiety, dizziness-related handicap, anxiety/depression, depersonalization/derealization, and perceived stress. After preliminary bivariate analyses, analysis of covariance was performed on the measurements of postural sway, spatial anxiety, and dizziness-related handicap (p < 0.05). Results: Higher intraindividual variability (reduced precision) on SVV estimations was evident in patients with PPPD compared to adults with no vestibular disease, which was related to the length of postural sway, to velocity displacement in the sagittal plane, as well as to spatial anxiety and common mental symptoms (including depersonalization/derealization symptoms). Covariance analysis showed contribution of these factors to the dizziness-related handicap reported by the patients. Conclusions: Unprecise graviception could be a contributing factor to the postural instability and mental symptoms reported by patients with PPPD, which in turn contribute to their dizziness-related handicap.

Construct Validity of a Wearable Inertial Measurement Unit (IMU) in Measuring Postural Sway and the Effect of Visual Deprivation in Healthy Older Adults.

Inertial Motor sensors (IMUs) are valid instruments for measuring postural sway but their ability to detect changes derived from visual deprivation in healthy older adults requires further investigations. We examined the validity and relationship of IMU sensor-derived postural sway measures compared to force plates for different eye conditions in healthy older adults (32 females, 33 males). We compared the relationship of the center of mass and center of pressure (CoM and CoP)-derived total length, root means square (RMS) distance, mean velocity, and 95% confidence interval ellipse area (95% CI ellipse area). In addition, we examined the relationship of the IMU sensor in discriminating between open- (EO) and closed-eye (EC) conditions compared to the force plate. A significant effect of the instruments and eye conditions was found for almost all the variables. Overall, EO and EC variables within (force plate r, from 0.38 to 0.78; IMU sensor r, from 0.36 to 0.69) as well as between (r from 0.50 to 0.88) instruments were moderately to strongly correlated. The EC:EO ratios of RMS distance and 95% CI ellipse area were not different between instruments, while there were significant differences between total length (p = 0.973) and mean velocity (p = 0.703). The ratios' correlation coefficients between instruments ranged from moderate (r = 0.65) to strong (r = 0.87). The IMU sensor offers an affordable, valid alternative to a force plate for objective, postural sway assessment.

Effects of Armor Design and Marksmanship Posture on Performance, Postural Sway and Perceived Workload During a Military Rifle Marksmanship Task.

This study investigated the effects of mass and vertical center-of-mass position of combat items attached to a tactical vest, as well as marksmanship posture on rifle marksmanship performance, postural sway, and perceived workload during a simulated rifle shooting task. A tactical vest serves as a load carriage system in addition to providing body protection. Its design, particularly the mass and vertical position of attached combat items, may impact postural control during rifle shooting and thus marksmanship performance. Thirty-two participants performed a simulated rifle shooting task on a force plate with a tactical vest on. Three independent variables were considered: load mass (4 levels), vertical load center-of-mass position (4 levels), and marksmanship posture (2 levels). The dependent variables were: 6 rifle marksmanship performance measures, 7 postural sway measures, and a perceived workload measure. Heavier load mass significantly degraded rifle marksmanship performance, and increased postural sway and perceived workload. Marksmanship posture significantly affected rifle marksmanship performance and postural sway. The kneeling posture resulted in less postural sway and better marksmanship performance than the standing posture. Vertical load center-of-mass position affected only part of the marksmanship performance measures and did not affect the measures of postural sway and perceived workload. Reducing combat item mass on tactical vests and enhancing soldier postural control ability would improve rifle marksmanship and soldier lethality. The study findings inform the development of future military tactical vests and rifle marksmanship training, highlighting the need for lightweight gear design and postural control training.

Assessment of postural sway with accelerometers: A comparison with force plate measures

Introduction &amp; Purpose Postural control is essential for maintaining balance during static and dynamic tasks. It is typically measured by centre of pressure (CoP) deviations using a ground reaction force plate (FP). Alternatively, more affordable and accessible accelerometer-based measures have been proposed. However, no consensus on the best protocol exists (Pinho et al., 2019). This study investigates the feasibility of assessing postural sway using linear acceleration data, considering sensor placement, task difficulty and analysed parameters. Methods The University of Vienna Ethics Committee approved this study (Ref. Nr. 01108). Ten healthy adults (6 M/4 F; 37.9 ± 14.8 years; BMI = 23.3 ± 2.3) performed eleven balance tasks, seven easy tasks from the Berg Balance Scale and four harder tasks with eyes closed, each lasting 20 seconds. Postural sway was assessed using a FP and five inertial measurement units (IMUs) attached to the upper spine (C7), lower spine (L1), sacrum and both thighs. Data were synchronously collected at 1500 Hz, zeroed, band pass filtered (3rd order Butterworth, 0.3-10 Hz; Martinez-Mendez et al., 2012), and cropped to 19 s. Outcomes included CoP path length, root mean square of sway amplitude in the anteroposterior (AP) and mediolateral (ML) directions for the FP, and RMS of the linear acceleration in AP and ML directions, along with their sum, for the ACC. Combinations of the two AP, two ML and two overall parameters were analysed by winsorised Pearson correlations and Bland Altman limits of agreement of z-scores for each task and for each sensor site. Fisher's Z-transformed correlation coefficients and limits of agreement were compared across task difficulty, parameter combinations, and sensor placement sites using a 3-way ANOVA. Results Pearson coefficients correlating the ACC parameters with the FP parameters averaged 0.60 (95% CI [0.54, 0.66]) for the easy tasks and 0.78 (95% CI [0.726, 0.84]) for the hard tasks, with no significant differences between sensor sites. A significant interaction (p &lt; 0.001) was found between task difficulty and parameter combination. Simple main effect analysis showed no difference between correlations of AP, ML and overall parameters for hard tasks but for easy tasks, where overall parameters showed the highest correlation, followed by ML and then AP parameters, all differing significantly from each other. The Bland Altman mean difference of z-scores between FP and ACC parameters was on average -0.002 (95% CI [-0.027, 0.024]). The lower and upper limits of agreement were on average -0.72 (95% CI [-0.84, -0.62]) and 0.73 (95% CI [0.62, 0.83]) respectively. Discussion The correlations between FP and ACC were higher during more challenging tasks, while the limits of agreement were broader and less precise in these tasks (data not shown). No optimal sensor placement site was identified as correlation and agreement between the two methods did not differ significantly between sites. The broad limits of agreement suggest relatively low precision of ACC measures compared to FP. Overall parameters often outperformed ML and AP parameters in terms of correlation and precision. Conclusion Accelerometer-based measures of postural sway showed high correlations with force plate measures but low precision when tasks where difficult enough to challenge participants’ balance. Sensor placement site did not influence correlation and precision. References Pinho, A. S., Salazar, A. P., Hennig, E. M., Spessato, B. C., Domingo, A., &amp; Pagnussat, A. S. (2019). Can we rely on mobile devices and other gadgets to assess the postural balance of healthy individuals? A systematic review. Sensors, 19(13), Article 13. https://doi.org/10.3390/s19132972 Martinez-Mendez, R., Sekine, M., &amp; Tamura, T. (2012). Postural sway parameters using a triaxial accelerometer: Comparing elderly and young healthy adults. Computer Methods in Biomechanics and Biomedical Engineering, 15(9), 899–910. https://doi.org/10.1080/10255842.2011.565753

Posture, balance and gait in axial spondyloarthritis: a case-control study.

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that primarily involves the axial skeleton but may also present with peripheral joint involvement and extra-articular involvement. The present study aims to quantitatively analyze posture, balance, and gait parameters in patients with axSpA and and assess associated factors. This cross-sectional case-control study included 51 axSpA patients (30 males, 21 females; mean age 40.94 ± 10.48 years) and 51 age- and sex-matched healthy controls. In patients with axSpA, the Ankylosing Spondylitis Disease Activity Score CRP, the Bath Ankylosing Spondylitis Disease Activity Index(BASDAI), the Bath Ankylosing Spondylitis Functional Index (BASFI), the Bath Ankylosing Spondylitis Metrology Index(BASMI), the Maastrich Ankylosing Spondylitis Enthesitis Score(MASES), and the Ankylosing Spondylitis Quality of Life(ASQoL) scale were used. For postural analysis, DIERS formetric (Diers GmbH, Schlangenbad, Germany) videoraster- stereography device was utilized. HUR SmartBalance BTG4 (HUR-labs Oy, Kokkola, Finland) balance platform was used for postural balance and limit of stability (LOS) measurement. Participants were evaluated using Berg Balance Scale (BBS), Functional Reach Test (FRT) and Timed Up and Go Test (TUG). The Zebris FDM type 3 (Zebris Medical GmbH, Germany) walking platform was used to measure the spatiotemporal parameters of the participants. Comparison of postural parameters showed that sagittal imbalance and cervical depth distance were increased in the axSpA group than in the healthy participants (p < 0.004). Comparison of functional balance parameters showed that BBS and FRT scores were significantly lower (p < 0.001) in the axSpA group than in the control group, while TUG scores were significantly higher (p < 0.001). The LOS values, which evaluate dynamic balance were significantly lower, indicating impairment, in the axSpA group. In the measurement of postural sway, which indicates static balance, all 23 subparameters were found to be similar. When analyzing the spatiotemporal gait parameters, in the axSpA group compared with those in the control group; Foot angles (p= 0.028) and stride width (p = 0.004) were increased, whereas step lengths (p = 0.004) and stride lengths (P = 0.004) were decreased. In the axSpA group the gait speed was decreased (p = 0.004). When axSpA was analyzed separately as radiographic and nonradiographic axSpA, similar findings were observed in posture, balance, and gait parameters. No significant difference was observed. We found that the clinical assessments most closely associated with posture, balance, and gait analyses were BBS, FRT, TUG, and BASFI.

Identifying the Problem Side with Single-Leg Squat and Hamstrings Flexibility for Non-Specific Chronic Low Back Pain.

Background and Objectives: In patients with non-specific chronic low back pain (LBP), their pain and problem sides can differ. Clinical Pilates assessment provides an approach to identify the problem side, but this approach requires experience and can be subjective. This study aimed to investigate if objective measures of single-leg squat postural control and hamstrings flexibility could identify the problem side in adults with non-specific chronic LBP. Materials and Methods: Forty adults with non-specific chronic LBP were tested on single-leg squat postural control and hamstrings flexibility. The problem side of participants was assessed with the Clinical Pilates method. Paired t-tests were used to compare the postural sway parameters of the single-leg squat and hamstrings flexibility between the problem and non-problem sides. Cohen's kappa was then used to assess the agreement of postural sway and flexibility measures with the Clinical Pilates method. Results: The problem side showed smaller vertical force variance, larger sway path distances, lower peak vertical force, smaller terminal knee flexion angle, longer time to complete the five single-leg squats, and tighter hamstrings as compared to the non-problem side. However, only the overall and anteroposterior sway path distances, terminal knee flexion angle, total squat duration, and hamstrings flexibility yielded moderate to strong agreement with the Clinical Pilates method. Conclusions: Single-leg squat postural sway parameters and hamstrings flexibility can objectively identify the problem side in adults with non-specific chronic LBP.

Analysis of posture and balance impairments in individuals with chronic nonspecific neck pain-an observational study.

Neck pain is one of the most burdensome chronic musculoskeletal problems globally. Impaired proprioception is associated with Chronic Nonspecific neck pain as the structures of the cervical spine are crucial for proprioception and balance. There is a paucity of literature examining objective measures of balance and postural sway in patients with Nonspecific neck pain. This study was observational and consisted of 126 samples (63 cases and 63 controls who were recruited using convenience sampling. The demographics of the samples were collected and the postural and balance impairment was assessed using Biodex Balance SD. Mean, Median, and SD were obtained and the inferential analysis was done using the Whitney U Test and the level of significance was accepted at p < 0.05. The subjects with neck pain showed had a lower static stability index, static sway index, static stability index- forward backward and static sway index lateral scores than the normal counterparts. There are significant differences in the overall static stability index, (p < 0.001). There was a significant difference in static sway index(p = 0.003), and static stability index lateral (p = 0.004). There was no significant difference for static sway index forward and backward (p = 0.550) and lateral sway index (p = 0.711). Subjects with neck pain showed had a lower static stability index, static sway index, static stability index- forward backward and static sway index lateral scores than the normal counterparts and there was a significant difference between the static sway and static stability index in forward and backward directions as well as in lateral direction. These findings may help to assess the specific balance parameters and address the underlying causes of balance issues in patients with neck pain and also provide a comprehensive care to the patients. The trial was registered with CTRI India with registration number: CTRI/2022/07/044222.

Mediolateral Postural Sway Velocity as a Possible Indicator of Ground Reaction Force-Derived 180⁰ Turn Performance in Male Soccer Players: A Cross-Sectional Study

The main aim of the study was to investigate the relationship between ground reaction force (GRF) derived postural sway and 180° turn performance in soccer players on the axis of dominant and non-dominant legs. Twenty-seven male soccer players (mean age 22.45 ± 2.7 years) from the same league level agreed to participate in the study. The participants underwent GRF-derived postural sway and 180⁰ turn tests using a force plate in separate sessions, with at least 24-hour intervals between sessions. Postural sway was assessed in anteroposterior and mediolateral directions during a single-leg stance, while the 180° turn performance was evaluated through GRF-derived turn time and turn sway. The correlation, multiple regression, and group differences were computed to test study hypotheses. Positive correlations were observed between postural sway measures and 180⁰ turn time for dominant and non-dominant legs (r-range from 0.384 to 0.550). No measure of postural sway was significantly related to the 180⁰ turn sway (p&amp;gt; 0.05). Multiple stepwise regression analysis indicated that mediolateral sway velocity explained 30% and 17% of the variance of 180⁰ turn time for dominant and non-dominant legs, respectively. No statistical inter-limb differences were noted for 180⁰ turn and postural sway parameters. The results suggest that improving single-leg postural performance may enhance male soccer players' 180° turn performance. Therefore, unilateral stability in the mediolateral direction should be considered a potential indicator of change of direction-based performances.

Impact of Differing Instability Devices on Postural Sway Parameters

Single-limb balance training is integral to preventing and rehabilitating lower extremity injuries. Previous investigations have shown that when using instability devices, differences may or may not exist in the postural sway parameters during use, depending on the specific devices being assessed. Thus, this investigation sought to examine the differences between a commonly used foam pad and a novel instability device (block) in postural sway measures. Twenty-two healthy individuals with no history of lower extremity injury or neurological disorders participated in this investigation. The participants performed three single-limb static balance exercises on a force platform sampling at 120 Hz. Each condition contained three 10-s trials separated by thirty seconds. The mean CoP values of the three trials in each condition were then compared using a within-subjects repeated-measures analysis of variance. Statistically significant differences were seen in the sway area between conditions (p = 0.009), the CoP path length (p = 0.007), the peak medial–lateral CoP displacement (p = 0.004), and the average sway velocity (p = 0.007). All variables displayed similar trends whereby the control condition showed significantly lower values than both instability devices, with no differences between devices. This investigation provides supporting evidence that different instability devices may deliver similar changes to postural sway parameters compared to control conditions. The novel block instability device used in this investigation may be used similarly to the traditional foam pad in prevention and rehabilitation settings based on the absence of differences between the two devices.

Relationship between functional movement screen scores and postural stability in football players: An asymmetrical approach

Introduction: Unilateral preference is dominant due to the intensive use of sport-specific movements in football. However, little is known about the possible correlation between unilateral functional movement and the center of pressure-based postural performance. The main aim of this study is to examine the correlation between functional movement screen (FMS) and postural stability in football players from an asymmetrical perspective. Materials and Methods: Fifty professional football players (male n = 25; age 21.40 ± 1.94 years; female n = 25; age 21.04 ± 1.24 years) volunteered for this study. All subjects completed a FMS test consisting of seven items and postural sway measures for dominant and non-dominant sides. Spearman’s correlation and the Mann-Whitney U-test were used for statistical processing. Results: A negative correlation was found between dominant and non-dominant sides FMS in scores and postural sway parameters in both male and female groups (p &lt; .05). Hurdle step (HS) and rotary stability (RS) proved to be strong predictors of postural stability for both groups (p &lt; .001). No significant differences were observed between dominant and nondominant sides in FMS items and postural sway parameters in both groups (p &gt; .05). Conclusions: The correlation of the FMS and postural sway measures may be useful to identify possible postural problems in football players. Therefore, the FMS test may be preferred by practitioners and physiotherapists.

Effects of virtual reality on balance in people with diabetes: a systematic review and meta-analysis.

This systematic review aims to identify, critically appraise, and synthesize the effects of virtual reality on balance in people with diabetes. Five biomedical databases were searched from inception to December 15, 2023. Clinical trials investigating the effects of virtual reality on performance-based or patient-reported outcome measures related to balance function among people with diabetes were included. Two independent reviewers conducted study selection, data extraction, and quality assessment. Cochrane risk-of-bias tool-2 were used to assess included studies. Meta-analysis was performed to examine the effects of the intervention. Six studies with a total of 257 participants were identified. Two studies had high risk of bias, and four studies had some concerns regarding risk of bias. No adverse events related to virtual reality were reported. Meta-analysis revealed significant improvements in the Berg Balance Scale (SMD = 1.56, 95% CI 0.71 to 2.40, p < 0.001), Timed Up and Go test (SMD = -0.74, 95% CI -1.21 to -0.28, p = 0.002), and falls efficacy (SMD = 0.99, 95% CI 0.43 to 1.54, p < 0.001) following virtual reality intervention. No significant differences were found for postural sway and single leg stance measures. Virtual reality-based rehabilitation demonstrates promising effects for improving balance in people with diabetes. Further studies with high methodological quality and large sample sizes are warranted. The online version contains supplementary material available at 10.1007/s40200-024-01413-7.

Standing Balance Conditions and Digital Sway Measures for Clinical Trials of Friedreich's Ataxia.

Progressive loss of standing balance is a feature of Friedreich's ataxia (FRDA). This study aimed to identify standing balance conditions and digital postural sway measures that best discriminate between FRDA and healthy controls (HC). We assessed test-retest reliability and correlations between sway measures and clinical scores. Twenty-eight subjects with FRDA and 20 HC completed six standing conditions: feet apart, feet together, and feet tandem, both with eyes opened (EO) and eyes closed. Sway was measured using a wearable sensor on the lumbar spine for 30 seconds. Test completion rate, test-retest reliability with intraclass correlation coefficients, and areas under the receiver operating characteristic curves (AUCs) for each measure were compared to identify distinguishable FRDA sway characteristics from HC. Pearson correlations were used to evaluate the relationships between discriminative measures and clinical scores. Three of the six standing conditions had completion rates over 70%. Of these three conditions, natural stance and feet together with EO showed the greatest completion rates. All six of the sway measures' mean values were significantly different between FRDA and HC. Four of these six measures discriminated between groups with >0.9 AUC in all three conditions. The Friedreich Ataxia Rating Scale Upright Stability and Total scores correlated with sway measures with P-values <0.05 and r-values (0.63-0.86) and (0.65-0.81), respectively. Digital postural sway measures using wearable sensors are discriminative and reliable for assessing standing balance in individuals with FRDA. Natural stance and feet together stance with EO conditions suggest use in clinical trials for FRDA. © 2024 International Parkinson and Movement Disorder Society.

Assessing Free-Living Postural Sway in Persons With Multiple Sclerosis.

Postural instability is associated with disease status and fall risk in Persons with Multiple Sclerosis (PwMS). However, assessments of postural instability, known as postural sway, leverage force platforms or wearable accelerometers, and are most often conducted in laboratory environments and are thus not broadly accessible. Remote measures of postural sway captured during daily life may provide a more accessible alterative, but their ability to capture disease status and fall risk has not yet been established. We explored the utility of remote measures of postural sway in a sample of 33 PwMS. Remote measures of sway differed significantly from lab-based measures, but still demonstrated moderately strong associations with patient-reported measures of balance and mobility impairment. Machine learning models for predicting fall risk trained on lab data provided an Area Under Curve (AUC) of 0.79, while remote data only achieved an AUC of 0.51. Remote model performance improved to an AUC of 0.74 after a new, subject-specific k-means clustering approach was applied for identifying the remote data most appropriate for modelling. This cluster-based approach for analyzing remote data also strengthened associations with patient-reported measures, increasing their strength above those observed in the lab. This work introduces a new framework for analyzing data from remote patient monitoring technologies and demonstrates the promise of remote postural sway assessment for assessing fall risk and characterizing balance impairment in PwMS.

Gender Effect on Motion Sickness Susceptibility

The study aimed was to determine whether there was a gender difference in sensitivity to visual stimulation-induced motion sickness (MS). Forty-nine participants (Female: 24, Male: 25) volunteered to join in the study. Participants were exposed to a visual video-recording stimulus to evoke the MS. Simulator Sickness Questionnaire (SSQ) was administered before, after, and 30 min after the MS stimulation to determine MS symptoms. Participants' self-report was used to identify motion sickness. Postural sway (PS) was measured before and immediately after MS stimulation. 58.3% of the female and 48.0% of the male reported that they had MS, while 41.7% of the female and 52.0% of the male reported that they did not have MS. Gender and MS distributions were not significant (p=0.469). Participants with MS before the stimulation had higher PS than those who declared no MS (p=0.008), but PS was not different after the stimulation (p=0.102). Although there was no difference in the pre-test (p=0.231), men with MS had higher PS than women with MS at the post-test (p=0.013). There was a significant increase in PS of men who declared that they had MS after the stimulation (p=0.012). The pre-test (p=0.899) and post-test (p=0.434) SSQ scores of men and women with MS were not different, while women had higher SSQ scores than men at the post-test 30 (p=0.020). Finally, there was no correlation between gender and rates of MS. In terms of symptom severity, females appear to be more susceptible to MS. PS may be a precursor to MS.

The Effect of Skeletal Muscle-Pump on Blood Pressure and Postural Control in Parkinson's Disease.

Activation of the calf (gastrocnemius and soleus) and tibialis anterior muscles play an important role in blood pressure regulation (via muscle-pump mechanism) and postural control. Parkinson's disease is associated with calf (and tibialis anterior muscles weakness and stiffness, which contribute to postural instability and associated falls. In this work, we studied the role of the medial and lateral gastrocnemius, tibialis anterior, and soleus muscle contractions in maintaining blood pressure and postural stability in Parkinson's patients and healthy controls during standing. In addition, we investigated whether the activation of the calf and tibialis anterior muscles is baroreflex dependent or postural-mediated. We recorded electrocardiogram, blood pressure, center of pressure as a measure of postural sway, and muscle activity from the medial and lateral gastrocnemius, tibialis anterior, and soleus muscles from twenty-six Parkinson's patients and eighteen sex and age-matched healthy controls during standing and with eyes open. The interaction and bidirectional causalities between the cardiovascular, musculoskeletal, and postural variables were studied using wavelet transform coherence and convergent cross-mapping techniques, respectively. Parkinson's patients experienced a higher postural sway and demonstrated mechanical muscle-pump dysfunction of all individual leg muscles, all of which contribute to postural instability. Moreover, our results showed that coupling between the cardiovascular, musculoskeletal, and postural variables is affected by Parkinson's disease while the contribution of the calf and tibialis anterior muscles is greater for blood pressure regulation than postural sway. The outcomes of this study could assist in the development of appropriate physical exercise programs that target lower limb muscles to improve the muscle-pump function and reduce postural instability in Parkinson's disease.

Cohort study of postural sway and low back pain: the Copenhagen City Heart Study

PurposeLow back pain is a significant health problem with a high prevalence. Studies of smaller cohorts of low back pain patients have indicated increased body sway. The present paper tests the hypothesis of an association between low back pain and postural sway in a large randomly selected population.MethodsThe current study used the fifth examination (2011–2015) of The Copenhagen City Heart Study where 4543 participated. The participants answered a self-administered questionnaire regarding pain, physical activity, smoking, alcohol consumption, education, and other lifestyle factors. Measurement of postural body sway was performed using the CATSYS system.ResultsTotally 1134 participants (25%) reported to have low back pain. Subjects with low back pain had higher sway area and sway velocity than subjects without.ConclusionWhen using multivariate statistical analysis, confounding factors such as male gender, higher age, larger body height, low education level, smoking, and low activity level explained the association between low back pain and postural sway.

The effect of selected rest break activities on reaction time, balance, and perceived discomfort after one hour of simulated occupational whole-body vibration exposure in healthy adults

Background & Objective : Negative health effects from occupational whole-body vibration (WBV) exposure during machinery operation include alterations in proprioception, vestibular function, reaction time, stress, motor response, and decrements in musculoskeletal health. To reduce WBV exposure during machinery operation, it may be possible to incorporate short rest break activities throughout the day. This study aims to determine if there are intervention activities that can minimize decrements in cognitive, proprioceptive, and musculoskeletal effects related to WBV exposure during machine operation. Materials & Methods Eleven healthy adults participated in four 1-hour sessions of ecologically valid WBV exposure followed by one of four 5-minute activities: sitting, walking, 2 min of gaze stabilization exercise (GSE) coupled with 3 min of trunk mobility exercise (GSE + MOBIL), or 2 min of GSE coupled with a 3-minute walk (GSE + WALK). Baseline and post-activity measurements (rating of perceived discomfort, balance and postural sway measurements, 5-minute psychomotor vigilance task test) were submitted to a paired t-test to determine the effect of WBV exposure and activities on physical, cognitive, and sensorimotor systems and to a repeated measures ANOVA to determine any differences across activities. Results We observed degradation of the slowest 10% reaction speed outcomes between baseline and post-activity after walking (7.3%, p < 0.05) and sitting (8.6%, p < 0.05) but not after GSE + MOBIL or GSE + WALK activities. Slowest 10% reaction speed after GSE + MOBIL activity was faster than all other activities. The rating of perceived discomfort was higher after SIT and WALK activities. There were no notable differences in balance outcomes. Conclusion When compared to sitting for 5 min, an activity including GSE and an active component, such as walking or trunk mobility exercises, resulted in maintenance of reaction time after WBV exposure. If confirmed in occupational environments, GSE may provide a simple, rapid, effective, and inexpensive means to protect against decrements in reaction time after WBV exposure.

Comparing a friction-based uni-directional treadmill and a slip-style omni-directional treadmill on first-time HMD-VR user task performance, cybersickness, postural sway, posture angle, ease of use, enjoyment, and effort

Treadmills allow users to translate their real world walking into movement in virtual worlds. Conventional treadmills used for fitness can be repurposed for users to move around in virtual reality, but permit walking in only one direction (uni-directional). Treadmills that allow walking in any direction (omni-directional) are available, in which users walk-in-place and their feet slip on a low-friction surface. Given that users can experience cybersickness and postural instability in virtual reality, this study explored user performance and side effects of using two different walking platforms: a conventional uni-directional treadmill and a slip-style omni-directional treadmill (Virtuix OMNI).All participants (n = 46) played a game in which they collected items distributed around a virtual world. Participants moved around the virtual world by walking on the conventional uni-directional treadmill (for 10 minutes) and on the omni-directional treadmill (for 10 minutes), whilst in HMD-VR, with a 5-minute break between platforms. Measurements of cybersickness, task achievement, distance covered, posture, postural sway and user experience (ease, enjoyment, and effort) were collected.Participants experienced significantly higher total cybersickness after walking on the slip-style omni-directional treadmill compared to after walking on the uni-directional treadmill (p=.003), and significantly higher Nausea and Oculomotor cybersickness after walking on the slip-style omni-directional treadmill compared to after walking on the uni-directional treadmill (p<.001 and p=.005 respectively). Participants had lowest postural sway after using the uni-directional treadmill compared to after using the omni-directional treadmill (p=.052). Participants completed significantly more of the task (p<.001) and walked further (p<.001) on the uni-directional treadmill compared to the omni-directional treadmill, and their posture angle (back tilt angle) was significantly more forward on the omni-directional treadmill compared to the uni-directional treadmill (p<.001). Significant differences were found with participants reporting walking on the omni-directional treadmill to be more difficult (p<.001), require more effort (p<.001) and be less enjoyable (p=.005), and changing direction to require more effort (p=.010), than compared to the uni-directional treadmill.This study recommends that alternatives to slip-style locomotion treadmills be developed due the non-natural walking action required to use slip-style platforms and the consequent negative psychophysiological impacts of their use with HMD-VR.

Fallers after stroke: a retrospective study to investigate the combination of postural sway measures and clinical information in faller's identification.

Falls can have devastating effects on quality of life. No clear relationships have been identified between clinical and stabilometric postural measures and falling in persons after stroke. This cross-sectional study investigates the value of including stabilometric measures of sway with clinical measures of balance in models for identification of faller chronic stroke survivors, and the relations between variables. Clinical and stabilometric data were collected from a convenience sample of 49 persons with stroke in hospital care. They were categorized as fallers (N = 21) or non-fallers (N = 28) based on the occurrence of falls in the previous 6 months. Logistic regression (model 1) was performed with clinical measures, including the Berg Balance scale (BBS), Barthel Index (BI), and Dynamic Gait Index (DGI). A second model (model 2) was run with stabilometric measures, including mediolateral (SwayML) and anterior-posterior sway (SwayAP), velocity of antero-posterior (VelAP) and medio-lateral sway (VelML), and absolute position of center of pressure (CopX abs). A third stepwise regression model was run including all variables, resulting in a model with SwayML, BBS, and BI (model 3). Finally, correlations between independent variables were analyzed. The area under the curve (AUC) for model 1 was 0.68 (95%CI: 0.53-0.83, sensitivity = 95%, specificity = 39%) with prediction accuracy of 63.3%. Model 2 resulted in an AUC of 0.68 (95%CI: 0.53-0.84, sensitivity = 76%, specificity = 57%) with prediction accuracy of 65.3%. The AUC of stepwise model 3 was 0.74 (95%CI: 0.60-0.88, sensitivity = 57%, specificity = 81%) with prediction accuracy of 67.4%. Finally, statistically significant correlations were found between clinical variables (p < 0.05), only velocity parameters were correlated with balance performance (p < 0.05). A model combining BBS, BI, and SwayML was best at identifying faller status in persons in the chronic phase post stroke. When balance performance is poor, a high SwayML may be part of a strategy protecting from falls.