The use of force-plate posturography in the assessment of postural instability

Cross-frequency modulation of postural fluctuations and scalp EEG in older adults: error amplification feedback for rapid balance adjustments

Virtual error amplification (VEA) in visual feedback enhances attentive control over postural stability, although the neural mechanisms are still debated. This study investigated the distinct cortical control of unsteady stance in older adults using VEA through cross-frequency modulation of postural fluctuations and scalp EEG. Thirty-seven community-dwelling older adults (68.1 ± 3.6 years) maintained an upright stance on a stabilometer while receiving either VEA or real error feedback. Along with postural fluctuation dynamics, phase-amplitude coupling (PAC) and amplitude-amplitude coupling (AAC) were analyzed for postural fluctuations under 2 Hz and EEG sub-bands (theta, alpha, and beta). The results revealed a higher mean frequency of the postural fluctuation phase (p = .005) and a greater root mean square of the postural fluctuation amplitude (p = .003) with VEA compared to the control condition. VEA also reduced PAC between the postural fluctuation phase and beta-band EEG in the left frontal (p = .009), sensorimotor (p = .002), and occipital (p = .018) areas. Conversely, VEA increased the AAC of posture fluctuation amplitude and beta-band EEG in FP2 (p = .027). Neither theta nor alpha band PAC or AAC were affected by VEA. VEA optimizes postural strategies in older adults during stabilometer stance by enhancing visuospatial attentive control of postural responses and facilitating the transition of motor states against postural perturbations through a disinhibitory process. Incorporating VEA into virtual reality technology is advocated as a valuable strategy for optimizing therapeutic interventions in postural therapy, particularly to mitigate the risk of falls among older adults.

Posture and postural dysfunction in dogs: Implications for veterinary physiotherapy

Postural assessment is an important part of the veterinary evaluation of a dog's neuromusculoskeletal function. It forms an important part of the clinical examination by physiotherapists and specialists in veterinary rehabilitation and sports medicine and is well researched in humans, which has allowed treatment approaches to be developed and validated. This narrative review aims to complement the veterinary literature, which largely quantifies the impact of various conditions on posture, by synthesising the physiotherapy literature, to help translate the use of postural assessment as a basis for the development and validation of treatment techniques to improve outcomes in dogs.

Older adults and individuals with Parkinson's disease control posture along suborthogonal directions that deviate from the traditional anteroposterior and mediolateral directions

A rich and complex temporal structure of variability in postural sway characterizes healthy and adaptable postural control. However, neurodegenerative disorders such as Parkinson's disease, which often manifest as tremors, rigidity, and bradykinesia, disrupt this healthy variability. This study examined postural sway in young and older adults, including individuals with Parkinson's disease, under different upright standing conditions to investigate the potential connection between the temporal structure of variability in postural sway and Parkinsonism. A novel and innovative method called oriented fractal scaling component analysis was employed. This method involves decomposing the two-dimensional center of pressure (CoP) planar trajectories to pinpoint the directions associated with minimal and maximal temporal correlations in postural sway. As a result, it facilitates a comprehensive assessment of the directional characteristics within the temporal structure of sway variability. The results demonstrated that healthy young adults control posture along two orthogonal directions closely aligned with the traditional anatomical anteroposterior (AP) and mediolateral (ML) axes. In contrast, older adults and individuals with Parkinson's disease controlled posture along suborthogonal directions that significantly deviate from the AP and ML axes. These findings suggest that the altered temporal structure of sway variability is evident in individuals with Parkinson's disease and underlies postural deficits, surpassing what can be explained solely by the natural aging process.

Keeping distance or getting closer: How others' emotions shape approach-avoidance postural behaviors and preferred interpersonal distance

Understanding the influence of emotions on social interactions is important for a global understanding of the dynamics of human behavior. In this study, we investigated the interplay between emotions, spontaneous approach or avoidance tendencies, and the regulation of interpersonal distance. Fifty-seven healthy adults participated in a three-part experiment involving exposure to approaching or withdrawing emotional faces (neutral, happy, sad, fearful, disgusted, angry). The sequence began with an initial computerized stop-distance task, followed by a postural task in which participants' approach or avoidance tendencies were quantified via center of pressure (CoP-Y) displacements on a force platform, and concluded with a final computerized stop-distance task. Our findings revealed a gradient in postural responses, with the most forward CoP-Y displacements for neutral and happy faces, indicative of approach tendencies. These were followed by lesser forward displacements for sad and fearful faces, and most pronounced backward displacements for disgusted and angry faces, indicating avoidance. Furthermore, we observed modulations in participants' preferred interpersonal distance based on emotional cues, with neutral and happy faces associated with shorter distances, and disgusted and angry faces linked to larger distances. Despite these similar results, no direct correlation was found between CoP-Y and preferred interpersonal distance, underscoring a dissociation between spontaneous and voluntary social behaviors. These results contribute to a better understanding of how emotional expressions shape social interactions and underscore the importance of considering emotional cues, postural action tendencies, and interpersonal distance in facilitating successful social interactions.

Multisensory and biomechanical influences on postural control in children

Children's ability to maintain balance requires effective integration of multisensory and biomechanical information. The current project examined the interaction between such sensory inputs, manipulating visual input (presence vs. absence), haptic (somatosensory) input (presence vs. absence of contact with a stable or unstable finger support surface), and biomechanical (sensorimotor) input (varying stance widths). Analyses of mean velocity of the center of pressure and the percentage stability gain highlighted the role of varying multisensory inputs in postural control. Developmentally, older children (6-11 years) showed a multisensory integration advantage compared with their younger counterparts (3-5.9 years), with the impact of varying sensory inputs more closely akin to that seen in adults. Subsequent analyses of the impact of anthropometric individual difference parameters (e.g., height, leg length, weight, areas of base of support) revealed a shifting pattern across development. For younger children, these parameters were positively related to postural stability across experimental conditions (i.e., increasing body size was related to increasing postural control). This pattern transitioned for older children, who showed a nonsignificant relation between body size and balance. Interestingly, because adults show a negative relation between anthropometric factors and stability (i.e., increasing body size is related to decreasing postural control), this shift for the older children can be seen as a developmental transition from child-like to adult-like balance control.

Concentrating to avoid falling: interaction between peripheral sensory and central attentional demands during a postural stability limit task in sedentary seniors

Evidence suggests falls and postural instabilities among seniors are attributed to a decline in both the processing of afferent signals (e.g., proprioceptive, vestibular) and attentional resources. We investigated the interaction between the non-visual and attentional demands of postural control in sedentary seniors. Old and young adults performed a postural stability limit task involving a maximal voluntary leaning movement with and without vision as well as a cognitive-attentional subtraction task. These tasks were performed alone (single-task) or simultaneously (dual-task) to vary the sensory-attentional demands. The functional limits of stability were quantified as the maximum center of pressure excursion during voluntary leaning. Seniors showed significantly smaller limits of postural stability compared to young adults in all sensory-attentional conditions. However, surprisingly, both groups of subjects reduced their stability limits by a similar amount when vision was removed. Furthermore, they similarly decreased their anterior-posterior stability limits when concurrently performing the postural and the cognitive-attentional tasks with vision. The overall average cognitive performance of young adults was higher than seniors and was only slightly affected during dual-tasking. In contrast, older adults markedly degraded their cognitive performance from the single- to the dual-task situations, especially when vision was unavailable. Thus, their dual-task costs were higher than those of young adults and increased in the eyes-closed condition, when postural control relied more heavily on non-visual sensory signals. Our findings provide the first evidence that as posture approaches its stability limits, sedentary seniors allot increasingly large cognitive attentional resources to process critical sensory inputs.

Plantar pressure distribution and altered postural control in multibacillary leprosy patients

BACKGROUND

Leprosy is a chronic infectious disease caused by Mycobacterium leprae, predominantly affecting the peripheral nerves, resulting in sensory and motor deficits in the feet. Foot ulcers and imbalances are frequent manifestations in leprosy, often correlating with diminished sensitivity. While clinical scales and monofilament esthesiometers are conventionally utilized to evaluate foot sensitivity and balance in these patients, their discriminatory power is limited and their effectiveness is greatly dependent on the examiner's proficiency. In contrast, baropodometry and posturography offer a more comprehensive evaluation, aiming to preempt potential damage events. This study aimed was to assess the correlation between baropodometry and force plate measurements in leprosy patients and control participants, to improve the prevention and treatment of foot ulcers and complications associated with leprosy.

METHODOLOGY

This cross-sectional study was conducted during 2022 and enrolled 39 participants (22 patients with multibacillary leprosy and 17 non-leprosy controls). Demographic data were collected, and a monofilament esthesiometer was used to assess sensory deficits. In addition, physical examinations and balance and plantar pressure tests were conducted. The Student's t-test was used to compare mean and maximum plantar pressures between groups. For most COP variables, a Mann-Whitney Wilcoxon test was used, except for AP amplitude which was analyzed with the Student's t-test due to its normal distribution. The relationship between foot pressure and balance control was assessed using Spearman's correlation, focusing on areas with significant pressure differences between groups.

PRINCIPAL FINDINGS

Leprosy patients showed increased pressure in forefoot areas (T1, M1, T2-T5, and M2) and decreased pressure in hindfoot regions (MH and LH) compared to controls. These patients also displayed higher AP and ML amplitudes, suggesting poorer COP control. Correlation analyses between the two groups revealed that foot plantar pressures significantly impact balance control. Specifically, increased T1 region pressures correlated with greater sway in balance tasks, while decreased MH region pressures were linked to reduced COP control.

CONCLUSIONS/SIGNIFICANCE

The findings suggest a joint disturbance of plantar pressure distribution and static balance control in leprosy patients. These alterations may increase the risk of tissue injuries, including calluses and deformities, as well as falls.

Hidden Markov Model for Parkinson's Disease Patients Using Balance Control Data

Understanding the behavior of the human postural system has become a very attractive topic for many researchers. This system plays a crucial role in maintaining balance during both stationary and moving states. Parkinson's disease (PD) is a prevalent degenerative movement disorder that significantly impacts human stability, leading to falls and injuries. This research introduces an innovative approach that utilizes a hidden Markov model (HMM) to distinguish healthy individuals and those with PD. Interestingly, this methodology employs raw data obtained from stabilometric signals without any preprocessing. The dataset used for this study comprises 60 subjects divided into healthy and PD patients. Impressively, the proposed method achieves an accuracy rate of up to 98% in effectively differentiating healthy subjects from those with PD.

Posture analysis in predicting fall-related injuries during French Navy Special Forces selection course using machine learning: a proof-of-concept study

INTRODUCTION

Injuries induced by falls represent the main cause of failure in the French Navy Special Forces selection course. In the present study, we made the assumption that probing the posture might contribute to predicting the risk of fall-related injury at the individual level.

METHODS

Before the start of the selection course, the postural signals of 99 male soldiers were recorded using static posturography while they were instructed to maintain balance with their eyes closed. The event to be predicted was a fall-related injury during the selection course that resulted in the definitive termination of participation. Following a machine learning methodology, we designed an artificial neural network model to predict the risk of fall-related injury from the descriptors of postural signal.

RESULTS

The neural network model successfully predicted with 69.9% accuracy (95% CI 69.3-70.5) the occurrence of a fall-related injury event during the selection course from the selected descriptors of the posture. The area under the curve value was 0.731 (95% CI 0.725-0.738), the sensitivity was 56.8% (95% CI 55.2-58.4) and the specificity was 77.7% (95% CI 76.8-0.78.6).

CONCLUSION

If confirmed with a larger sample, these findings suggest that probing the posture using static posturography and machine learning-based analysis might contribute to inform risk assessment of fall-related injury during military training, and could ultimately lead to the development of novel programmes for personalised injury prevention in military population.

Pressure-Sensitive Walkway System for Evaluation of Lameness in Dogs Affected by Unilateral Cranial Cruciate Ligament Rupture Treated with Porous Tibial Tuberosity Advancement

The aim of this study was to objectively evaluate lameness in dogs affected by a unilateral cranial cruciate ligament rupture (CrCLR) treated with porous tibial tuberosity advancement before surgery and at three different timepoints after surgery, using the GAITRite® system (version 4.9Wr), a pressure-sensitive walkway system that is able to calculate several spatiotemporal gait parameters simultaneously for each limb. The dogs walked on the pressure-sensitive walkway before (T0) and 30 (T1), 90 (T2), and 120 (T3) days after surgery. Pressure measurements (gait lameness score and total pressure index %) were collected for S (treated with porous TTA) and C (healthy contralateral limb) at T0, T1, T2, and T3 and statistically evaluated. An ANOVA test was performed to compare the data, and a value of p < 0.05 was considered significant. Twenty dogs (n = 20) of various common breeds and ages with CrCLR were enrolled in the study. The results showed that there was a statistically significant difference in the GAIT4Dog® lameness score (GLS) and TPI% between S and C for each timepoint. Statistically significant differences in the GLS and TPI% between S at T0 and S at T2 and between S at T0 and S at T3 (p < 0.001) were found. The results showed that there was a statistically significant difference in the GAIT4Dog® lameness score (GLS) and TPI% between S and C for each timepoint. Statistically significant differences in the GLS and TPI% between S at T0 and S at T2 and between S at T0 and S at T3 were found. The GLS and TPI% increased statistically significantly from 90 days after surgery compared to the preoperative measurements. Moreover, comparing the GLS and TPI% between the treated limb and the control limb showed that a statistically significant difference remained at each timepoint.

Overweight in elderly increases postural instability during sit-to-stand test: a Kinect-based assessment

BACKGROUND

Being overweight increases the risk of falls and subsequent injuries. However, conventional functional balance tests may not be appropriate for this population as body weight can affect test performance. Thus, it is crucial to develop reliable methods for assessing balance ability in overweight individuals.

AIM

The purpose of this study was to utilize a portable gaming device (Kinect Xbox 360) to measure the center of mass (CoM) of elderly individuals and compare the results between normal weight and overweight elderly women.

METHODS

The study included 64 female elderly individuals who were divided into two groups: 32 normal weight and 32 overweight subjects, matched for age (matched pairs design). The study collected the body's CoM during the five-time sit-to-stand test (FTSST) using Kinect camera. Additionally, the participants underwent the time up and go test (TUGT) and one-leg standing balance (OLSB) tests. The Kinect Xbox 360 demonstrated high test-retest reliability for measuring body's center of mass sway, with ICC3,1 value of 0.982 in the vertical direction, 0.983 in the mediolateral (ML) direction, and 0.997 in the anteroposterior (AP) direction. Additionally, the technical error of measurement (TEM) was very low at 0.006, 0.002, and 0.004, respectively. The % coefficient of variation ranged from 1.31% to 5.68%, indicating good measurement consistency.

RESULTS

Overweight individuals took longer to complete FTSST and TUGT compared to normal weight individuals, but no significant difference was observed in OLSB tests. Moreover, overweight elderly individuals had greater sway length in the ML and AP directions compared to normal weight elderly individuals.

DISCUSSION AND CONCLUSION

Overweight elderly individuals had poorer balance than their normal weight counterparts when using Kinect camera. The researchers suggest that Kinect device can be a cost-effective alternative to measure balance performance among overweight elderly in the community-based setting.

Different neuromuscular control mechanisms regulate static and dynamic balance: A center-of-pressure analysis in young adults

The analysis of the center of pressure (CoP) trajectory, derived from force platforms, is a widely accepted measure to investigate postural balance control. The CoP trajectory could be analyzed as a physiological time-series through a general stochastic modeling framework (i.e., Stabilogram Diffusion Analysis (SDA)). Critical point divides short-term from long-term regions and diffusion coefficients reflect the level of stochastic activity of the CoP. Sample Entropy (SampEn) allows quantifying the CoP complexity in terms of regularity. Thus, this study aimed to understand whether SDA and SampEn could discriminate the neuromuscular control mechanisms underpinning static and dynamic postural tasks. Static balance control and its relationship with dynamic balance control were investigated through the CoP velocity (Mean Velocity) and the area of the 95th percentile ellipse (Area95). Balance was assessed in 15 subjects (age: 23.13 ± 0.99 years; M = 9) over a force platform under two conditions: static (ST) and dynamic, both in anterior-posterior (DAP) and medio-lateral (DML) directions. During the DAP and DML, subjects stood on an unstable board positioned over a force platform. Short-term SDA diffusion coefficients and critical points were lower in ST than in DAP and DML (p < 0.05). SampEn values resulted greater in ST than in DAP and DML (p < 0.001). As expected, lower values of Area95 (p < 0.001) and Mean Velocity (p < 0.001) were detected in the easiest condition, the ST, compared to DAP and DML. No significant correlations between static and dynamic balance performances were detected. Moreover, differences in the diffusion coefficients were detected comparing DAP and DML (p < 0.05). In the anterior-posterior direction, the critical point occurred at relatively small intervals in DML compared to DAP (p < 0.001) and ST (p < 0.001). In the medio-lateral direction, the critical point differed only between DAP and DML (p < 0.05). Overall, SDA analysis pointed out a less tightly regulated neuromuscular control system in the dynamic tasks, with closed-loop corrective feedback mechanisms called into play at different time intervals in the three conditions. SampEn results reflected more attention and, thus, less automatic control mechanisms in the dynamic conditions, particularly in the medio-lateral task. The different neuromuscular control mechanisms that emerged in the static and dynamic balance tasks encourage using both static and dynamic tests for a more comprehensive balance performance assessment.

Center of Mass Estimation Using a Force Platform and Inertial Sensors for Balance Evaluation in Quiet Standing

Accurate estimation of the center of mass is necessary for evaluating balance control during quiet standing. However, no practical center of mass estimation method exists because of problems with estimation accuracy and theoretical validity in previous studies that used force platforms or inertial sensors. This study aimed to develop a method for estimating the center of mass displacement and velocity based on equations of motion describing the standing human body. This method uses a force platform under the feet and an inertial sensor on the head and is applicable when the support surface moves horizontally. We compared the center of mass estimation accuracy of the proposed method with those of other methods in previous studies using estimates from the optical motion capture system as the true value. The results indicate that the present method has high accuracy in quiet standing, ankle motion, hip motion, and support surface swaying in anteroposterior and mediolateral directions. The present method could help researchers and clinicians to develop more accurate and effective balance evaluation methods.

Center of mass-based posturography for free living environment applications

BACKGROUND

Postural assessment is crucial as risk of falling is a major health problem for the elderly. The most widely used devices are force and balance plates, while center of pressure is the most studied parameter as measure of neuromuscular imbalances of the body sway. In out-of-laboratory conditions, where the use of plates is unattainable, the center of mass can serve as an alternative. This work proposes a center of mass-based posturographic measurement for free living applications.

METHODS

Ten healthy and ten Parkinson's disease individuals (age = 26.1 ± 1.5, 70.4 ± 6.2 years, body mass index = 21.7 ± 2.2, 27.6 ± 2.8 kg/m², respectively) participated in the study. A stereophotogrammetric system and a force plate were used to acquire the center of pressure and the 5th lumbar vertebra displacements during the Romberg test. The center of mass was estimated using anthropometric measures. Posturographic parameters were extracted from center of pressure, center of mass and 5th lumbar vertebra trajectories. Normalized root mean squared difference was used as metric to compare the trajectories; Spearman's correlation coefficient was computed among the posturographic parameters.

FINDINGS

Low values of the metric indicated a good agreement between 5th lumbar vertebra trajectory and both center of pressure and center of mass trajectories. Statistically significant correlations were found among the postural variables.

INTERPRETATION

A method to perform posturography tracking the movement of the 5th lumbar vertebra as an approximation of center of mass has been presented and validated. The method requires the solely kinematic tracking of one anatomical landmark with no need of plates for free living applications.

Methods of postural analysis in connection with the stomatognathic system. A systematic review

This systematic review aimed to identify the main tools used to analyze the relationship between the postural and stomatognathic systems. The study followed the PRISMA guidelines, and data were collected from Science Direct and PubMed databases to identify articles published until December 2022. After applying inclusion and exclusion criteria, 26 articles were selected from the initial 903 articles. The selected articles were full-text studies in English or Romanian, examining the relationship between dental occlusion and posture, measuring postural parameters using various tools, implementing occlusal changes, evaluating patients with permanent dentition, or analyzing the connection between occlusion and posture in a unidirectional manner. The findings indicate that orthognathic surgery and orthodontic mouthguards can significantly enhance postural balance and athletic performance. In addition, 63% of the studies concluded that varying modifications and occlusal conditions impact posture. Notable differences exist concerning posture and Angle dental occlusion classes, and different occlusal devices used to simulate malocclusion can affect patients' postural systems in response to external stimuli. The stabilometry platform is the predominant method for measuring postural parameters; however, other researchers have employed raster stereography, photogrammetry, mobile phone apps, and the Fukuda-Unterberger test. Consequently, interventions targeting the stomatognathic system should consider potential variations in the postural system.

Studies in the Falls Efficacy Scale-International for patients with cervical compressive myelopathy: Reliability, validity, and minimum clinically important difference

CONTEXT

Patients with cervical compressive myelopathy (CCM) often complain of body balance problems, such as fear of falling and bodily unsteadiness. However, no accepted patient-reported outcome measures (PROMs) for this symptomatology exist. The Falls Efficacy Scale-International (FES-I) is one of the most widely used PROMs for evaluating impaired body balance in various clinical fields.

OBJECTIVE

To examine reliability, validity, and minimum clinically important difference (MCID) of the FES-I for the evaluation of impaired body balance in patients with CCM.

METHODS

Patients who underwent surgery for CCM were retrospectively reviewed. The FES-I was administered preoperatively and at 1 year postoperatively. Further, cJOA-LE score (subscore for lower extremities in the Japanese Orthopaedic Association score for cervical myelopathy) and stabilometric data, obtained at the same time points of the FES-I administration, were analyzed. Reliability was examined through internal consistency with Cronbach's alpha. Convergent validity was studied using correlation analysis. The MCID was estimated using anchor- and distribution-based methods.

RESULTS

Overall, 151 patients were included for analysis. Cronbach's alpha coefficient was the acceptable value of 0.97 at both baseline and 1 year postoperatively. As for convergent validity, the FES-I had significant correlations with the cJOA-LE score and stabilometric parameters both at baseline and 1 year postoperatively. The MCID calculated using anchor- and distribution-based methods was 5.5 and 10, respectively.

CONCLUSION

FES-I is a reliable and valid PROM to evaluate body balance problems for the CCM population. The established thresholds of MCID can help clinicians recognize the clinical significance of changes in patient status.

Using Wearable Inertial Sensors to Monitor Effectiveness of Different Types of Customized Orthoses during CrossFit® Training

BACKGROUND

Dynamic balance plays a key role in high-impact sports, such as CrossFit, where athletes are required to maintain balance in various weightlifting exercises. The loss of balance in these sport-specific movements may not only affect athlete performance, but also increase the risk of injuries.

OBJECTIVES

The aim of the study is to achieve greater insight into the balance and athlete position during the CrossFit training by means of inertial sensors, with a particular focus on the role of different custom foot orthoses (CFOs) in order to detect correlations with the role of the cavus foot.

METHODS

A total of 42 CrossFit^® athletes, aged 25 to 42 years, were enrolled in this study. One-way ANOVA tests with post-hoc analysis of variance were used to compare foot posture groups and effects of different types of customized foot orthoses.

RESULTS

When comparing the effects of CFOs with the respective balance basal level during the pistol squat exercise, we observed a significant (p = 0.0001) decrease in the sway area, antero-posterior displacement (APD) and medio-lateral displacement (MLD) compared to the basal using both types of CFOs.

CONCLUSION

No significant positive effects of CFOs were observed in some static tests. On the contrary, positive effects of CFOs and, in particular, postural insoles, are relevant to dynamic balance.

Posturographic Standards for Optimal Control of Human Standing Posture

Static posturography is a simple non-invasive technique commonly used in contemporary labs and clinics to quantify the central nervous system adaptive mechanisms involved in the control of posture and balance. Its diagnostic value, however, is quite limited due to the lack of posturographic standards for stable posture. To solve this problem, in this research, we aimed to establish reference values for the stable human posture using our novel parameters of static posturography including the sway anteroposterior directional index (DIAP), the mediolateral directional index (DIML), the stability vector amplitude (SVamp), and the stability vector azimuth (SVaz). Towards this end, in a population of young (mean age 22 yrs), healthy able-bodied volunteers (50 males and 50 females), trajectories of postural sway, based upon the center-of-pressure (COP), were assessed. The experiment consisted of ten 60s trials that were carried out 5 times while subjects were standing quietly on the force plate with eyes open (EO test) and 5 times with eyes closed (EC test). Results showed that in young healthy subjects, regardless of gender, the basic variables of COP remained at the following levels: SVamp = 9.2 ± 1.6 mm/s, SVaz = 0.9 ± 0.1 rad, and directional indices DIAP = 0.7 ± 0.05, DIML = 0.56 ± 0.06. Some of the measures were sensitive to visual input (EC trials) and showed a weak to moderate correlation with anthropometric features. These measures can be recommended as reference values that characterize the most stable erect posture.

Model of the Performance Based on Artificial Intelligence-Fuzzy Logic Description of Physical Activity

The aim of the study was to build a fuzzy model of lower limb peak torque in an isokinetic mode. The study involved 93 male participants (28 male deaf soccer players, 19 hearing soccer players and 46 deaf untraining male). A fuzzy computational model of different levels of physical activity with a focus on the lower limbs was constructed. The proposed fuzzy model assessing lower limb peak torque in an isokinetic mode demonstrated its effectiveness. The novelty of our research lies in the use of hierarchical fuzzy logic to extract computational rules from data provided explicitly and then to determine the corresponding physiological and pathological mechanisms. The contribution of our research lies in complementing the methods for describing physiology, pathology and rehabilitation with fuzzy parameters, including the so-called dynamic norm embedded in the model.

Characterization of trial duration in traditional and emerging postural control measures

Researchers may select from varied technological and practical options when evaluating balance. Methodological choices inform the quantitative outcomes observed and allow practitioners to diagnose balance abnormalities. Past investigations have differed widely on sampling duration, and these discrepancies hinder comparisons among studies and confidence in outcomes where trials were excessively short. This study aimed to identify necessary trial lengths for common and emerging center of pressure-based measures. We hypothesized that dependent variables would fluctuate over time but eventually reach a stable magnitude. Ninety-seven apparently healthy adults performed quiet standing for 180-seconds (s) with eyes (A) open and (B) closed on a force platform. Anterior-posterior and medial-lateral elements of the center of pressure were used to calculate velocity, time-to-boundary, and Hurst exponents using 15, 30, 90, 120, 150, and 180 s of data. Two-way repeated measures ANOVAs were used to differentiate postural measures over time and between vision conditions. Outcomes were considered stable when significant changes in the measure were no longer observed in the time factor. Dependent measures stabilized for velocity between 60 and 120 s, time-to-boundary between 120 and 150 s, and the Hurst exponent between 30 and 120 s. Velocity measures stabilized quicker with eyes open, whereas vision had no effect or the eyes closed condition was faster to stabilize in time-to-boundary and detrended fluctuation analysis measures. We conclude that 150 s of standing data is sufficient to capture a broad range of postural stability outcomes regardless of vision condition.

The effect of six week virtual reality training on the improvement of functional balance in women with type-I osteoporosis: A preliminary study

Purpose

This preliminary study aimed to investigate the effects of exergames in a virtual reality environment to improve functional balance during goal-directed functional tasks in postmenopausal women with osteoporosis.

Methods

Twelve volunteer postmenopausal women with osteoporosis were randomly assigned to virtual reality (VRT, n = 6) and conventional multimodal (CMT, n = 6) training groups. The exercise was performed for 6 weeks, 3 days weekly, and 18 sessions. Using a force platform, functional balance assessments were made through four dynamic tasks, including performance-based limits of stability (LOS), curve tracking (CT), sit-to-stand (STS), and turning before and after 18 sessions of treatment. Each task's time-dependent center of pressure (COP) variables was separately calculated via Kistler-Mars software.

Results

The COP variables of LOS and CT tasks were significantly improved after 6 weeks of CMT and VRT (P ≤ 0.05). In the VRT group, the rising index (P < 0.00), COP sway velocity in STS, and Turn sway were significantly reduced (P < 0.05). Following the VRT, the mean difference of forwarding maximum COP excursion increased (P = 0.03), and errors in CT (P = 0.03) significantly decreased.

Conclusion

The VRT and CMT improved the COP sway parameters during weight-shifting tasks. The VRT was more effective than CMT in increasing the ability to control weight-shifting and dynamic functional tasks in postmenopausal women with osteoporosis. This approach in training has suitable potential to provide convenient error feedback learning.

Probing the posture with machine learning provides physiological evidence supporting the enhanced body awareness hypothesis in trait mindfulness

Enhanced body awareness has been suggested as one of the cognitive mechanisms that characterize mindfulness. Yet neuroscience literature still lacks strong empirical evidence to support this claim. Body awareness contributes to postural control during quiet standing; in particular, it may be argued that body awareness is more strongly engaged when standing quietly with eyes closed, because only body cues are available, than with eyes open. Under these theoretical assumptions, we recorded the postural signals of 156 healthy participants during quiet standing in Eyes closed (EC) and Eyes open (EO) conditions. In addition, each participant completed the Freiburg Mindfulness Inventory, and his/her mindfulness score was computed. Following a well-established machine learning methodology, we designed two numerical models per condition: one regression model intended to estimate the mindfulness score of each participant from his/her postural signals, and one classifier intended to assign each participant to one of the classes “Mindful” or “Non-mindful.” We show that the two models designed from EC data are much more successful in their regression and classification tasks than the two models designed from EO data. We argue that these findings provide the first physiological evidence that contributes to support the enhanced body awareness hypothesis in mindfulness.

Postural Sway and Muscle Activity Dynamics of Upright Standing on Sloped Surfaces

During upright standing, individuals often use co-contraction muscle activity at the ankle joint when encountering increased postural difficulty; however, this strategy has been shown to be maladaptive. The purpose of the current investigation was to examine the effect of sloped standing on postural sway and muscle co-contraction at the ankle joint as a function of postural difficulty. Twelve young (21.67 ± 1.11 years) adults performed upright standing on flat, declined, and inclined support surfaces. Center of pressure displacements indexed postural sway while electromyography data were collected for the tibialis anterior and gastrocnemius medialis muscles. A co-contraction index and a nonlinear coupling metric (cross-approximate entropy) were computed between ankle dorsiflexor and plantar flexor muscles (tibialis anterior/gastrocnemius medialis) activity. The results showed that higher degrees of postural difficulty led to increased amounts of sway as well as increased sway regularity. Lower co-contraction index was observed for higher degrees of postural difficulty; however, increased dynamic coupling occurred with deviations from the flat standing condition. Overall, increased postural difficulty as manipulated by sloped standing (in either inclined or declined conditions) resulted in individuals adopting a more regular sway trajectory that may be due, in part, to a stronger dynamic coupling strategy occurring at the neuromuscular level.

Incongruity of Geometric and Spectral Markers in the Assessment of Body Sway

Different measurements of body oscillations in the time or frequency domain are being employed as markers of gait and balance abnormalities. This study investigates basic relationships within and between geometric and spectral measures in a population of young adult subjects. Twenty healthy subjects stood with parallel feet on a force platform with and without a foam pad. Adaptation effects to prolonged stance were assessed by comparing the first and last of a series of eight successive trials. Centre of Foot Pressure (CoP) excursions were recorded with Eyes Closed (EC) and Open (EO) for 90s. Geometric measures (Sway Area, Path Length), standard deviation (SD) of the excursions, and spectral measure (mean power Spectrum Level and Median Frequency), along the medio-lateral (ML) and antero-posterior (AP) direction were computed. Sway Area was more strongly associated than Path Length with CoP SD and, consequently, with mean Spectrum Level for both ML and AP, and both visual and surface conditions. The squared-SD directly specified the mean power Spectrum Level of CoP excursions (ML and AP) in all conditions. Median Frequency was hardly related to Spectrum Level. Adaptation had a confounding effect, whereby equal values of Sway Area, Path Length, and Spectrum Level corresponded to different Median Frequency values. Mean Spectrum Level and SDs of the time series of CoP ML and AP excursions convey the same meaning and bear an acceptable correspondence with Sway Area values. Shifts in Median Frequency values represent important indications of neuromuscular control of stance and of the effects of vision, support conditions, and adaptation. The Romberg Quotient EC/EO for a given variable is contingent on the compliance of the base of support and adaptation, and different between Sway Area and Path Length, but similar between Sway Area and Spectrum Level (AP and ML). These measures must be taken with caution in clinical studies, and considered together in order to get a reliable indication of overall body sway, of modifications by sensory and standing condition, and of changes with ageing, medical conditions and rehabilitation treatment. However, distinct measures shed light on the discrete mechanisms and complex processes underpinning the maintenance of stance.

Integration of reginal shear measurements at the foot-ground interface during routine balance assessment of the elderly population

BACKGROUND

Force-plate posturography offers a convenient way for quantitative assessment of postural stability in the elderly. However, studies focusing on routine balance assessment have usually not taken reginal shear distributions (i.e., arising from horizontal forces) into consideration.

RESEARCH QUESTION

(1) Does plantar shear distribution differ between young and elderly subjects during upright standing? (2) How do the maximum plantar shear forces vary at different regions of the foot?

METHODS

The new reginal shear measurement (RSM) method can simultaneously capture the three-dimensional force distributions at regional plantar sites while subjects maintaining standing balance. The feasibility of the proposed method in characterizing the magnitude and distribution of plantar shear forces was tested in thirty-two normal young and nineteen elderly subjects. Statistical analysis was performed using the independent samples t-test for both the continuous and ordinal variables.

RESULTS

For regional AP shear forces, statistically significant differences were found between the two groups for the toe region of the right foot and the midfoot of both feet. For ML shear distributions, statistically significant differences were found at nearly all plantar sites expect for the hallux and lateral metatarsal. The maximum increase in ML shear forces occurred in the toe region of the right foot, where the peak shear values were 113.16% higher than those of the young subjects. The peak ML shear occurred in the midfoot were averagely 83.19% and 70.57% higher in the elderly's left and right feet, respectively.

SIGNIFICANCE

The RSM method may offer unique solutions to identify functional decline in postural control of the elderly. The plantar shear pattern has potential to become an important parameter in evaluating one's balance performance during upright standing.

EMD-Based Method for Supervised Classification of Parkinson’s Disease Patients Using Balance Control Data

There has recently been increasing interest in postural stability aimed at gaining a better understanding of the human postural system. This system controls human balance in quiet standing and during locomotion. Parkinson’s disease (PD) is the most common degenerative movement disorder that affects human stability and causes falls and injuries. This paper proposes a novel methodology to differentiate between healthy individuals and those with PD through the empirical mode decomposition (EMD) method. EMD enables the breaking down of a complex signal into several elementary signals called intrinsic mode functions (IMFs). Three temporal parameters and three spectral parameters are extracted from each stabilometric signal as well as from its IMFs. Next, the best five features are selected using the feature selection method. The classification task is carried out using four known machine-learning methods, KNN, decision tree, Random Forest and SVM classifiers, over 10-fold cross validation. The used dataset consists of 28 healthy subjects (14 young adults and 14 old adults) and 32 PD patients (12 young adults and 20 old adults). The SVM method has a performance of 92% and the Dempster–Sahfer formalism method has an accuracy of 96.51%.

Increased 18F-FDG Uptake in the Axillary Lymph Nodes of the Vaccinated Side Associated with COVID-19 Vaccination

A 50-year-old female patient underwent (¹⁸fluorine-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) following modified radical mastectomy for cancer of the left breast. Ten days before the PET/CT, the coronavirus disease-2019 (COVID-19) vaccine was injected intramuscularly into the right deltoid muscle. Increased (¹⁸F-FDG uptake of maximum standardized uptake value (11.0) was observed in the lymph nodes of the right axilla, which had not been observed in the previous PET/CT. The size of the oval-shaped lymph nodes was up to approximately 11×9 mm; however, it was larger than that observed on the previous PET/CT. We contemplate that the increased (¹⁸F-FDG uptake was a reactive change in the lymph nodes associated with the COVID-19 vaccine.

The effect of body mass reduction on functional stability in young obese women

Functional stability is necessary for everyday activities. The studies have indicated the deterioration of functional stability during standing in the obese adults. This study aimed to determine whether the 3-month weight-loss program that resulted in body mass reduction equal to or greater than 5% of the initial body mass would improve functional stability in young obese women. For the purpose of this study, the data of 30 females were included. Their mean age was 35.8 ± 9.2. The women performed the anterior limit of stability test on the force platform twice: before and after weight-loss program. Their BMI at two sessions was 36.1 ± 5.1 and 32.3 ± 5, respectively. After the weight loss program, the COP velocities were increased in both phases of the anterior limit of stability test: the dynamic transition from standing to maximal forward-leaning and the maintenance of maximal forward-leaning position (p < 0.05). No significant changes in the values of the COP parameters were found in the eyes-closed trial (p > 0.05). The results suggest that body mass reduction in young obese women led to improved mobility and postural control when visual cuing was available. The longer-lasting weight-loss program might be necessary to observe this effect under visual deprivation conditions. Body mass should be reduced in obese patients to improve their mobility and functional stability; it may prevent unexpected falls.

Balance Differences between North and South American Older Adults: A Cross-Sectional, Age and Sex Matched Study

This study aimed to characterize the risk of falling in low-, moderate- and high-risk participants from two different geographical locations using a portable force-plate. A sample of 390 older adults from South and North America were matched for age, sex, height and weight. All participants performed a standardized balance assessment using a force plate. Participants were classified in low, moderate and high risk of falling. No differences were observed between South and North American men, nor comparing North American men and women. South American women showed the significantly shorter center of pressure path length compared to other groups. The majority of the sample was categorized as having low risk of falling (male: 65.69% and female: 61.87%), with no differences between men and women. Moreover, no differences were found between North vs. South Americans, nor between male and female groups compared separately. In conclusion, South American women had better balance compatible with the status of the 50–59 years’ normative age-range. The prevalence of low falls risk was~61–65%; the prevalence of moderate to high risk was~16–19%. The frequency of fall risk did not differ significantly between North and South Americans, nor between males and females.

The Effects of Surgery on Postural Instability in Patients With Cervical Compressive Myelopathy: Evaluating Subjective Perceptions and Objective Measurements

STUDY DESIGN

A retrospective study.

OBJECTIVE

To investigate the effects of surgery on the subjective perception of bodily unsteadiness and the objective measurements of postural instability in patients with cervical compressive myelopathy (CCM).

SUMMARY OF BACKGROUND DATA

Several studies have demonstrated that CCM patients have impaired postural stability and investigated its surgical outcomes. However, these studies have only objectively measured postural stability by using a stabilometer or three-dimensional motion capture system. There have been no studies examining the subjective perception of postural instability in CCM patients.

MATERIALS AND METHODS

We retrospectively reviewed patients who underwent decompressive surgery for CCM. The Fall Efficacy Scale-International (FES-I) and a self-prepared questionnaire were used to evaluate subjective perception of bodily unsteadiness. To objectively assess postural instability, a stabilometric analysis was performed with the following parameters: sway area (SwA, cm2), sway velocity (SwV, cm/s), and sway density (SwD, /cm). The evaluations were performed preoperatively, during the early postoperative period (3-6 mo postoperatively), and at 1-year postoperatively in patients with CCM. The evaluation results were compared with age-matched, sex-matched, and body mass index-matched healthy subjects.

RESULTS

We included 70 CCM patients and 36 healthy subjects in this study. In both the FES-I and self-prepared questionnaire, CCM patients reported significantly milder postoperative bodily unsteadiness. The stabilometric parameters were significantly improved during the postoperative period when compared with preoperative values. Nevertheless, neither the self-reported outcome measures nor stabilometric parameters of CCM patients reached the levels of those in healthy controls in the postoperative period.

CONCLUSION

This was the first study to examine CCM surgical outcomes in terms of both subjective perception and objective postural instability. While both objective postural stability and subjective perception improved following decompressive surgery, they did not reach the levels seen in healthy participants.

LEVEL OF EVIDENCE

Level III.

Influence of footwear on postural sway: A systematic review and meta-analysis on barefoot and shod bipedal static posturography in patients and healthy subjects

BACKGROUND

Bipedal static posturography is widely used to assess postural control. However, standardized methods and evidence on the influence of footwear on balance in comparison to barefoot stance is sparse.

RESEARCH QUESTIONS

Is bipedal static posturography applied in a standardized way with respect to demographics and the experimental set-up (systematic review)? Does habitual footwear influence postural control in comparison to barefoot condition during bipedal static posturography in adult patients and healthy subjects (meta-analysis)?

METHODS

For this systematic review and meta-analysis, a comprehensive follow-up literature search was conducted from March 2009 until January 2020 according to the PRISMA guidelines. Original, research articles reporting on bipedal, unsupported, static posturography in adults (≥18 years) were included according to inclusion criteria (age, sex, height, weight, duration, repetitions, visual/foot condition, sampling frequency). Studies comparing habitual footwear with barefoot condition during bipedal static posturography were included for the meta-analysis. Center of pressure parameters (sway velocity, range, root mean square, paths lengths) with subjects having eyes closed (EC) or open (EO) were analyzed using random effects models.

RESULTS

For this systematic review and meta-analysis, 207 and eight out of 5189 studies with 12'341 and 156 subjects, respectively, were eligible. Most studies (89%) reported barefoot, 5% shod, and 6% barefoot and shod measurements. Less than half of studies (44%) included patients of which the minority (13%) suffered from neurological disease. Sway velocity in the anterior-posterior direction was higher in habitual shoes compared to barefoot with EC (SMD: 1.08; 95% CI: 0.68-1.48; p < 0.01; I² = 0%), with EO (SMD: 0.68; 95% CI: 0.11-1.26; p = 0.02; I² = 1%), and in the medio-lateral direction with EC (SMD: 1.30; 95% CI: 0.76-1.85, p < 0.01; I² = 37%).

SIGNIFICANCE

Methodical heterogeneity of bipedal static posturography hampers studies' comparability. Thus, we provide a standardized approach to increase knowledge whether habitual footwear decrease postural control in comparison to barefoot stance.

Prevalence of Sarcopenia and Its Association with Quality of Life, Postural Stability, and Past Incidence of Falls in Postmenopausal Women with Osteoporosis: A Cross-Sectional Study

In this cross-sectional analysis of 61 postmenopausal osteoporosis patients who regularly visited an osteoporosis outpatient clinic, we aimed to clarify the prevalence of sarcopenia and its related clinical factors. Of 61 patients (mean age 77.6 ± 8.1 years), 24 (39.3%) had osteosarcopenia and 37 (60.7%) had osteoporosis alone. Age, nutritional status, and the number of prescribed drugs were associated with the presence of sarcopenia (p = 0.002, <0.001, and 0.001, respectively), while bone mineral density (BMD) and % young adult mean BMD were not (p = 0.119 and 0.119, respectively). Moreover, patients with osteosarcopenia had lower quality of life (QOL) scores, greater postural instability, and a higher incidence of falls in the past year than patients with osteoporosis alone. In contrast, BMD status showed no correlation with the nutritional status, QOL score, postural instability, or incidence of falls in the past year. In conclusion, the incidence of sarcopenia was relatively high among postmenopausal osteoporosis female patients in an osteoporosis outpatient clinic. Our results suggest that in addition to routine BMD evaluation, assessment and management of sarcopenia may be promoted at osteoporosis outpatient clinics to limit the risk of falls and prevent consequent fragility fractures in osteoporosis patients.

Changes in postural balance associated with a woman's aging process

CONTEXT

Aging causes a progressive worsening in postural balance, affecting functional independence and increasing the risk of falls.

OBJECTIVE

The aim of the study was to evaluate the effect of aging on the static balance in women from 50-years to 89-years of age.

DESIGN

This was a cross-sectional study, with 400 irregularly active women were evaluated and grouped by age: Group 6^th decade (age 50 to 59) ‒ 58 participants; Group 7^th decade (age 60 to 69) ‒ 214 participants; Group 8^th decade (age 70 to 79) ‒ 92 participants; Group 9^th decade (age 80 to 89) ‒ 36 participants. Postural balance was evaluated using a portable force platform in a standard standing position, with Eyes Open (EO) and Eyes Closed (EC).

RESULTS

In the two measurement conditions, the elderly women in Group 9^th decade presented mediolateral displacement and range, and mean velocity greater than the women's values in Groups 6^th and 7^th decade. In the EO e EC situation, the displacement was higher in the elderly Group 9^th decade compared to younger groups. Group 8^th has a mean velocity greater than Group 6^th decade in the EO situation.

CONCLUSIONS

Posturography showed a decline in postural balance with advancing age, suggesting that the 9^th decade of life is a borderline age to this detriment due to an increase in postural instability.

Brain Oxygenation in Post-concussion Combat Sport Athletes

Purpose: Investigate the feasibility of a non-invasive method to evaluate the physical and cognitive repercussions of long-lasting post-concussion effects in professional combat sports athletes. To help athletes return to professional combat, there is a need for unbiased objective tools and techniques used as a prognostic method of recovery after Sport Related Concussion (SRC). Methods: Six mild Traumatic Brain Injury (mTBI) athletes, age 20 ÷ 43 yr (1 female, 5 males) and 7 not concussed (NC) participants (amateur), age 24 ÷ 38 yr (3 females, 4 males), were tested Inspired/expired gas concentration, Cerebral changes in oxygenated hemoglobin (Δ[HbO2]) and deoxygenated hemoglobin (Δ[HHb]) were measured using near infrared spectroscopy (NIRS) with a 3-step protocol: rest before maximal oxygen uptake (VO2max) test, hypercapnia, and recovery after VO2max test. The brain oxygenation and respiratory parameters of both sample sets were calculated using a non-parametric test (Mann-Whitney U test). Aerobic fitness outcome was quantified through mean average using the Bruce test. Participants performed Fitt's test using a laptop and analysis of medio-lateral and anterior-posterior range of oscillation was carried out via a force platform Romberg test. Results: mTBI group showed statistically significant differences in saturated hemoglobin Δ[HbO2] (p < 0.001) during rest and recovery phase after maximal incremental exercise, in medio-lateral sway eyes open (p = 0.008, NC 25.35 ± 4.11 mm and mTBI 17.65 ± 4.79 mm). VO2max revealed no significant differences between the two groups: NC 47.47 ± 4.91 mTBI 49.58 ± 5.19 ml/kg/min-1. The 2 groups didn't differ for maximum power output (NC 220 ± 34, mTBI 255 ± 50 W). End-tidal fractional concentration of O2 (FetO2 NC15.20 ± 0.41, mTBI 16.09 ± 0.68) throughout hypercapnia, saturated blood hemoglobin (Δ[HbO2]) revealed significant differences with the mTBI group. No differences emerged from Fitt's test. Conclusions: It emerges that NIRS is able to reveal differences in long time outcomes of mTBI. The medio-lateral variations cannot be considered as a marker of long-term damage in athletes specifically trained for balance.

Cross-Cultural Adaptation, Reliability, and Psychophysical Validation of the Pain and Sleep Questionnaire Three-Item Index in Finnish

Reciprocal relationships between chronic musculoskeletal pain and various sleep disturbances are well established. The Pain and Sleep Questionnaire three-item index (PSQ-3) is a concise, valid, and reliable patient-reported outcome measure (PROM) that directly evaluates how sleep is affected by chronic low back pain (CLBP). Translation and cross-cultural validation of The Pain and Sleep Questionnaire three-item index Finnish version (PSQ-3-FI) were conducted according to established guidelines. The validation sample was 229 subjects, including 42 pain-free controls and 187 subjects with chronic musculoskeletal pain. Our aims were to evaluate internal consistency, test-retest reliability, measurement error, structural validity, convergent validity, and discriminative validity and, furthermore, to study the relationships between dizziness, postural control on a force plate, and objective sleep quality metrics and total PSQ-3-FI score. The PSQ-3-FI demonstrated good internal consistency, excellent test-retest reliability, and small measurement error. Confirmatory factor analysis confirmed acceptable fit indices to a one-factor model. Convergent validity indicated fair to good correlation with pain history and well-established pain-related PROMs. The PSQ-3-FI total score successfully distinguished between the groups with no pain, single-site pain, and multisite pain. A higher prevalence of dizziness, more impaired postural control, and a general trend towards poorer sleep quality were observed among subjects with higher PSQ-3-FI scores. Postural control instability was more evident in eyes-open tests. The Finnish PSQ-3 translation was successfully cross-culturally adapted and validated. The PSQ-3-FI appears to be a valid and reliable PROM for the Finnish-speaking CLBP population. More widespread implementation of PSQ-3 would lead to better understanding of the direct effects of pain on sleep.

Are weight shifting and dynamic control strategies different in postmenopausal women with and without type-I osteoporosis?

OBJECTIVE

Tracking postural control processes at dynamic conditions might help develop an appropriate rehabilitation program in osteoporotic women. This study aimed to investigate the differences in center of pressure (COP) control at weight shifting and dynamic tasks between postmenopausal women with and without type-I osteoporosis. Also, we investigated the correlations between bone mineral density (BMD), the activity-specific balance confidence questionnaire (ABC-Q) score, and postural control parameters.

METHOD

A total of 62 volunteer postmenopausal women participated in this study. The participants were classified into non-osteoporotic (NOP, T-score >1, n = 35, age = 60.04± 5.33 years) and osteoporotic (OP, T-score < -2.5, n = 27, age = 61.88 ± 5.34 years) groups. The COP sway was recorded using a Kistler force plate during performance-based Limits of Stability (LOS), Curve Tracking (CT), Sit to Stand (STS), and Turn tasks. In addition, the level of balance confidence in daily activities was evaluated by ABC-Q.

RESULTS

In the LOS task, COP sway velocity in the anterior direction (P = 0.02) and COP maximum excursion in the side-to-side direction (right-side P = 0.027 and left-side P = 0.044) were significantly lower in the OP than the NOP group. In the CT task, all the quantified parameters, including errors and area, showed significantly lower values in the OP group than the NOP group (P < 0.05). In the STS task, the rising index score was significantly higher in the OP group than the NOP group (P = 0.014). The two groups had an equal ABC-Q score (P = 0.175). The COP sway variables correlated significantly with the lumbar and femoral neck T-score (P < 0.05).

CONCLUSION

BMD decline can change weight shifting and dynamic postural control in postmenopausal women.

Multisensory postural control in adults: Variation in visual, haptic, and proprioceptive inputs

Maintaining balance is fundamentally a multisensory process, with visual, haptic, and proprioceptive information all playing an important role in postural control. The current project examined the interaction between such sensory inputs, manipulating visual (presence versus absence), haptic (presence versus absence of contact with a stable or unstable finger support surface), and proprioceptive (varying stance widths, including shoulder width stance, Chaplin [heels together, feet splayed at approximately 60°] stance, feet together stance, and tandem stance) information. Analyses of mean velocity of the Centre of Pressure (CoP) revealed significant interactions between these factors, with stability gains observed as a function of increasing sensory information (e.g., visual, haptic, visual + haptic), although the nature of these gains was modulated by the proprioceptive information and the reliability of the haptic support surface (i.e., unstable versus stable finger supports). Subsequent analyses on individual difference parameters (e.g., height, leg length, weight, and areas of base of support) revealed that these variables were significantly related to postural measures across experimental conditions. These findings are discussed relative to their implications for multisensory postural control, and with respect to inverted pendulum models of balance. (185 words).

Evaluation of postural stability in patients screened for osteoporosis: A retrospective study of 1086 cases

BACKGROUND

Although the interactions between balance, falls and fracture risk have been demonstrated in various aspects, the clinical focus of fracture risk evaluation has been on bone properties, e.g., bone mineral density (BMD). Accordingly, the role of balance parameters in the setting of osteoporosis assessment remained to be further explored.

RESEARCH QUESTION

Is postural stability assessed by Romberg quiet stance posturography influenced by BMD or prior fragility fractures in a cohort of more than 1000 patients screened for osteoporosis?

METHODS

Patients who completed both Romberg test and dual energy X-ray absorptiometry (DXA) were included retrospectively from a large database. Quantification of the Romberg test was performed by using posturography. Center of pressure (CoP) movements were tracked and the corresponding path length for ten seconds as well as an ellipse area including 90 % of all CoP were calculated. To determine potential predictors of posturography, simple and multiple linear regression analyses were performed including DXA results, grip strength, age, sex and BMI. As a secondary outcome, the influence of a previous fragility fracture on postural stability was evaluated.

RESULTS

Overall, 1086 patients (801 women, 285 men) met the inclusion criteria. Lower femoral BMD T-score (p < 0.05), higher age (p < 0.001) and male sex (p < 0.001) were associated with higher Romberg path length (both eyes open and eyes closed). Both women and men with any previous fragility fracture showed significantly increased values in the path length with eyes open (p < 0.05) and eyes closed (women p < 0.001, men p < 0.05) compared to those without a history of a fragility fracture.

SIGNIFICANCE

Our study indicates that postural stability is affected by femoral BMD, age and sex. As a history of prior fragility fracture was associated with postural instability, assessment and management of impaired balance in everyday clinical practice is advisable for optimal fracture prevention.

Transient characteristics of body sway during single-leg stance in athletes with a history of ankle sprain

BACKGROUND

The role of the measurements of postural stability in the context of screening for ankle sprain risk is still equivocal. Transient characteristics of body sway have been suggested as an alternative or an improvement to traditional whole-trial analyses.

RESEARCH QUESTION

Are transient characteristics of body sway sensitive to the history of ankle sprain?.

METHODS

The assessment of 30-s single-leg body sway was performed on a group of 93 athletes from basketball, soccer, tennis and running who reported at least 1 ankle sprain in the last 12 months, while a group of 244 athletes from the same disciplines served as a control group without an ankle sprain reported for the same time period. We considered the mean center-of-pressure (CoP) velocity, CoP amplitude and CoP frequency. In addition to traditional whole-trial variables, we calculated the relative differences between the 1 st and the 2nd (DIF_21) and 1 st and 3rd (DIF_31) 10-s time intervals within the whole trial.

RESULTS

The indexes of transient characteristics of body sway (i.e., the DIF_21 and DIF_31) were in trivial or weak correlations with whole-trial variables (all r ≤ 0.29). Athletes with ankle sprain history exhibited smaller CoP ML velocity (p = 0.002) and larger CoP ML frequency (p = 0.001). In the injured group, the injured leg exhibited lower total and medial-lateral (ML) CoP velocity (p = 0.005-0.040), as well as lower CoP ML amplitude (p = 0.002) and higher CoP ML frequency (p = 0.010). The transient characteristics of body sway (DIF_21 and DIF_31) were very similar between the groups and between the injured and uninjured legs.

SIGNIFICANCE

Transient characteristics of body sway do not appear to differentiate the athletes with and without a history of ankle sprain. Further research is needed to confirm if the transient characteristics of body sway could be used for detection of risk of falls in older adults or assessment of athletic performance.

Cross-cultural adaptation and validation of the Finnish version of the central sensitization inventory and its relationship with dizziness and postural control

BACKGROUND

Central Sensitization (CS) involves dysfunction in neurophysiological mechanisms that increase neuronal responses to both noxious and non-noxious stimuli in the central nervous system. The Central Sensitization Inventory (CSI) is considered the leading patient-reported outcome measure for assessing CS-related symptoms. The aim of this study was to translate and cross-culturally adapt the CSI into Finnish (CSI-FI) and to evaluate its psychometric properties.

METHODS

Translation and cross-cultural validation of the CSI was conducted according to established guidelines. The validation sample was 229 subjects, including 42 pain free controls and 187 subjects with chronic musculoskeletal pain. The CSI-FI was evaluated for internal consistency, test-retest reliability, exploratory factor analysis with maximum likelihood extraction, relationship with subject-reported outcome measures [Tampa scale of kinesiophobia (TSK), the Depression scale (DEPS), 5-level EQ-5D version (EQ-5 L-5D), Roland-Morris Disability Questionnaire (RMDQ), and Pain and Sleep Questionnaire Three-Item Index (PSQ-3)], pain history, subjective symptoms of dizziness, and CS-related diagnoses on CSI part B. Furthermore, we studied the ability of the CSI-FI to distinguish pain free controls, subjects with chronic pain in a single body area, and subjects with multisite chronic pain. In addition, we studied the relationship of CSI-FI scores with postural control on a force plate.

RESULTS

The CSI-FI demonstrated good internal consistency (0.884) and excellent test-retest reliability (0.933) with a 7 ± 1 day gap between test administrations. Exploratory factor analysis with maximum likelihood extraction yielded a one factor solution. Fair to good correlations were found between the CSI-FI and the TSK, DEPS, EQ-5 L-5D, RMDQ, and PSQ-3. Subjective symptoms of dizziness correlated better with CSI-FI scores than any of the CS-related diagnoses on CSI part B. Total CSI-FI scores successfully distinguished between pain free controls, subjects with chronic pain in a single body area, and subjects with multisite chronic pain. The multisite pain group reported significantly more dizziness symptoms than the other two groups. Force plate measurements showed no relationship between postural control and CSI-FI scores.

CONCLUSION

The CSI-FI translation was successfully cross-culturally adapted and validated into Finnish. CSI-FI psychometric properties and scores were all in acceptable levels and in line with previous CSI validations. The CSI-FI appears to be a valid and reliable instrument for assessing CS-related symptomology in Finnish-speaking populations.

Review of the Upright Balance Assessment Based on the Force Plate

Quantitative assessment is crucial for the evaluation of human postural balance. The force plate system is the key quantitative balance assessment method. The purpose of this study is to review the important concepts in balance assessment and analyze the experimental conditions, parameter variables, and application scope based on force plate technology. As there is a wide range of balance assessment tests and a variety of commercial force plate systems to choose from, there is room for further improvement of the test details and evaluation variables of the balance assessment. The recommendations presented in this article are the foundation and key part of the postural balance assessment; these recommendations focus on the type of force plate, the subject's foot posture, and the choice of assessment variables, which further enriches the content of posturography. In order to promote a more reasonable balance assessment method based on force plates, further methodological research and a stronger consensus are still needed.

MCQ-Balance: a method to monitor patients with balance disorders and improve clinical interpretation of posturography

Background

An estimated 20% to 30% of the global population has suffered a vertiginous episode. Among them, 20% do not receive a clear diagnosis. Improved methods, indicators and metrics are necessary to assess the sensory systems related to balance, especially when patients are undergoing treatment for vertiginous episodes. Patients with balance disorders should be monitored for changes at the individual level to gather objective information. In this study, we evaluate the use of the MCQ-Balance (Measure, Classify and Qualify) assessment for examining a patient’s balance progression using tests to measure static balance control and dynamic postural balance with a stabilometric platform.

Materials and Methods

The MCQ-Balance assessment comprises three stages: (i) measuring the progression of each variable between two separate and consecutive days (called sessions) using the Magnitude-Based Decision analysis; (ii) classifying the progression of the patient’s balance with a score; and (iii) qualifying the progression of the patient’s balance from the resulting scores using a set of rules. This method was applied to 42 patients with balance disorders of peripheral or central origin characterised by vertigo as the cardinal symptom. Balance progression was measured using the MCQ-Balance assessment over the course of three months, and these results were compared with the assessment of a clinical expert.

Results

The MCQ-Balance assessment showed an accuracy of 83.4% and a Cohen’s Kappa coefficient of 0.752 compared to the assessment of a clinical expert.

Conclusion

The MCQ-Balance assessment facilitates the monitoring of patient balance and provides objective information that has the potential to improve medical decision making and the adjustment of individual treatment.

New methods of posturographic data analysis may improve the diagnostic value of static posturography in multiple sclerosis

Background

Early and accurate diagnosis of multiple sclerosis (MS) is crucial for its effective treatment. In MS diagnostic, neuronal networks that control posture and movement are of particular importance, which performance can be assessed using static posturography. Unfortunately, most of the commercially available posturographic platforms are not equipped with the appropriate procedures.

Methods

To solve this problem, the postural sway trajectories have been recorded in 55 MS patients while standing quiet with eyes open (EO), and then with eyes closed (EC). The trajectories were analyzed using our novel methods of postural sway parametrization, including sway stability vector (SV), anteroposterior and mediolateral sway indices (DIAP and DIML).

Results

The results exhibited unique postural sway patterns that may be attributed to MS. Our novel parametrization methods of postural sway showed pathology specific increase of the postural sway velocity in EC tests. Additionally, we documented the abnormal alterations of the anteroposterior (AP) and the mediolateral (ML) sway indices that were also uniquely dependent on visual input. In EC tests, patients exhibited a characteristic pattern of sway increase in both AP and ML directions that correlated with the advance of the disease as measured by the EDSS Kurtzke scale and Functional System Scores.

Conclusions

The applied in the present study our novel posturographic metrics give the assessment a diagnostic value. It allows us to recommend the static posturography test as a simple and safe supplementary clinical tool in the diagnosis of MS. In the assessment of MS pathology or the effects of its treatment, the impact of vision on the sway stability vector seems the most important factor.

The Effects of Exergaming Training on Balance in Healthy Elderly Women-A Pilot Study

Our aim was to observe, through objective testing using an assessment module incorporated in a new exergaming system, whether elderly people's static and functional balance is improved by a balance exergaming training program based on movements performed in everyday life. Thirteen healthy elderly women participated in 12 sessions of balance-based exergaming training (three times a week, 30 min per session). All objective outcomes, the quiet standing test, functional balance test (FBT), and limit of stability (LOS) test, were measured on three occasions: before intervention, after six training sessions, and after the completion of the four-week program. The results showed a significant improvement in LOS performance after the intervention. In FBT, participants exhibited a significant decrease (p < 0.01; Kendall's W = 0.5) in the average time to target hit after six trainings. The average center of pressure velocity increased after six and 12 sessions, however did not reach significance (p = 0.053); nevertheless the size of the effect was large (η_p2 = 0.22). The parameters of the quiet standing test were not significantly affected by the training. The results support the need for more definite and objective studies assessing exergaming for balance in elderly.

Evaluation of balance functions using temporo-spatial gait analysis parameters in patients with brain lesions

This study aimed to compare gait analysis and balance function measurements, such as the Berg balance scale (BBS) score to seek specific measurements that can represent the balance functions of patients with brain lesions. Additionally, we also compared other different gait function scale scores with gait analysis measurements. This study included 77 patients with brain lesions admitted to our institution between January 2017 and August 2020. Their gait analysis parameters and clinical data, including personal data; clinical diagnosis; duration of the disease; cognition, ambulation, and stair-climbing sub-scores of the modified Barthel index (MBI); manual muscle test (MMT) findings of both lower extremities; functional ambulation category (FAC); and BBS score, were retrospectively analyzed. A multiple linear regression analysis was performed to identify the gait analysis parameters that would significantly correlate with the balance function and other physical performances. In the results, the BBS scores were significantly correlated with the gait speed and step width/height². However, the other gait function measurements, such as the FAC and ambulation and stair-climbing sub-scores of the MBI, were correlated only with the gait speed. Additionally, both the summations of the lower extremity MMT findings and anti-gravity lower extremity MMT findings were correlated with the average swing phase time. Therefore, in the gait analysis, the gait speed may be an important factor in determining the balance and gait functions of the patients with brain lesions. Moreover, the step width/height² may be a significant factor in determining their balance function. However, further studies with larger sample sizes should be performed to confirm this relationship.

Validation of a smartphone embedded inertial measurement unit for measuring postural stability in older adults

BACKGROUND

Identifying older adults with increased fall risk due to poor postural control on a large scale is only possible through omnipresent and low cost measuring devices such as the inertial measurement units (IMU) embedded in smartphones. However, the correlation between smartphone measures of postural stability and state-of-the-art force plate measures has never been assessed in a large sample allowing us to take into account age as a covariate.

RESEARCH QUESTION

How reliably can postural stability be measured with a smartphone embedded IMU in comparison to a force plate?

METHODS

We assessed balance in 97 adults aged 50-90 years in four different conditions (eyes open, eyes closed, semi-tandem and dual-task) in the anterio-posterior and medio-lateral directions. We used six different parameters (root mean square and average absolute value of COP displacement, velocity and acceleration) for the force plate and two different parameters (root mean square and average absolute value of COM acceleration) for the smartphone.

RESULTS

Test-retest reliability was smaller for the smartphone than for the force plate (intra class correlation) but both devices could equally well detect differences between conditions (similar Cohen's d). Parameters from the smartphone and the force plate, with age regressed out, were moderately correlated (robust correlation coefficients of around 0.5).

SIGNIFICANCE

This study comprehensively documents test-retest reliability and effect sizes for stability measures obtained with a force plate and smartphone as well as correlations between force plate and smartphone measures based on a large sample of older adults. Our large sample size allowed us to reliably determine the strength of the correlations between force plate and smartphone measures. The most important practical implication of our results is that more repetitions or longer trials are required when using a smartphone instead of a force plate to assess balance.

Maturation of the postural control in adolescent girls: A 3-year follow-up study

BACKGROUND

Stable posture is a manifestation of the appropriate functioning of the neuromuscular system that is essential for proper motor development and control. Balance and stability of the erect posture are shaped during the entire childhood to culminate in its full efficiency in adolescent subjects.

METHODS

In this 3-year follow-up study, the process of the postural control maturation has been assessed in a group of 18 girls at the transition period between childhood to adolescence. Their balance and postural stability control were assessed using standard static posturography supplemented by two postural stability tests: the rising-on-toes (ROT), and the maximum forward lean (MFL), all performed with (EO) and without vision (EC). Balance control was analyzed with the sway vector (SV) and sway directional indices, whereas the anteroposterior trajectories of the center-of- pressure (COP) during forward-leaning and the raise-on-toes tests were used to determine changes in postural stability control.

RESULTS

The study documented that stability control in girls aged 11-13 is shaped according to their own pace of development. Their postural sway was characterized by the lower COP velocity but very sensitive to visual input. The directional sway measures remained at the same level for the entire period of observation. MFL and ROT tests provided similar information on postural stability and its dependence on visual input. These tests allow for more thorough assessment of postural stability to compare with quiet stance testing.

SIGNIFICANCE

Subtle changes in postural control in adolescents could be assessed based on the results of combined static and dynamic tests. In particular, the ROT test can be recommended for the assessment of postural stability.

TEMPORAL AND FRACTAL BEHAVIOR OF THE CENTER OF PRESSURE IN PARKINSONIAN AND HEALTHY ELDERLY COHORTS DURING QUIET STANDING

This study investigated the quantitative scaling properties of the center of pressure (COP) as well as the spatial-temporal properties of the COP to elucidate the postural control behavior of healthy elderly (HE) adults and adults with Parkinson’s disease (PD) during quiet standing. Eighteen adults with PD and eighteen HE adults participated in this study. The COP movements were recorded while participants stood on either a firm surface or on a foam pad with their eyes either opened or closed. The sway ranges in the anterior–posterior (AP) ([Formula: see text] and medio-lateral (ML) ([Formula: see text] directions, the total length of the trajectory ([Formula: see text], sway area ([Formula: see text], and scaling exponents ([Formula: see text] from detrended fluctuation analysis were computed from the measured COP data. All temporal variables of the COP in all conditions were found to be significantly larger in the PD group than in the HE group. Low scaling exponents obtained for the PD group showed this group possessed diminished postural control ability compared to the HE group. The PD group showed unpredictable open-loop control in both the AP and ML directions. This proprioceptive control became predictable and the time scale relations decreased as the postural challenges increased. The AP and ML closed-loop control of the PD group was more predictable than that of the HE group only when proprioception was distorted using intact visual input, and the visual and proprioceptive inputs were both intact.

REPEATABILITY OF SWAY MEASURES IN UPPER EXTREMITY WEIGHT-BEARING

Background

Analysis of upper extremity weight bearing ability is important for athletes as some function largely in a closed chain capacity (e.g., wrestling, football, gymnastics); also, all require closed chain upper extremity function during strength and conditioning. Additionally, in a rehabilitation setting, closed chain upper extremity functional testing is often used as a return to play criterion. Lower extremity sway measures (biomechanical and clinical) have been published widely and have established reliability and validity; however, the reliability of upper extremity sway biomechanical measures has not been investigated to date.

Hypothesis/Purpose

The purpose of this study was to determine the repeatability of a variety of force plate measurements during an upper extremity task in an athletic population. It was hypothesized that variables measuring upper extremity sway in a closed kinetic chain position would have excellent reliability.

Study Design

Cross-sectional.

Methods

All data were collected using a force plate system with commercially available software. Four hundred and ninety healthy Division I athletes were tested for both their dominant and non-dominant upper extremity at one of two testing sessions. Subjects were instructed to stay as still as possible while maintaining a full plank position with one upper extremity on the force plate and the contralateral upper extremity behind their back. Two, 20-second trials were performed for each extremity. Variables measured included average sway velocity (ASV), sway velocity in medial-lateral (SVML) and anterior-posterior (SVAP) directions, sway velocity at 1^st and 2^nd time intervals for AP (VAP1 and 2) and ML (VML1 and 2) directions, and sway frequency in the AP direction for 1^st and 2^nd time intervals (FreAP1 and 2). Intraclass correlation coefficients (ICC_(2,1)) and their 95% confident intervals were calculated for all force plate variables for 980 limbs.

Results

No difference was seen between left and right extremities for any measure (p > 0.05). ICC's ranged from 0.61-0.90 for all variables, indicating moderate to excellent reliability for all variables.

Conclusion

Upper extremity sway biomechanical variables using a force plate system have moderate to excellent reliability. These results are important prior to validation and clinical utilization of these measures including baseline testing, return to play guidelines, and injury prevention parameters.

Level of Evidence

3.