Center Of Pressure Analysis Research Articles

Center of Pressure- and Machine Learning-based Gait Score and Clinical Risk Factors for Predicting Functional Outcome in Acute Ischemic Stroke

ObjectivesTo investigate whether machine learning (ML)-based center of pressure (COP) analysis for gait assessment, when used in conjunction with clinical information, offers additive benefits in predicting functional outcomes in patients with acute ischemic stroke. DesignA prospective, single-center cohort study. SettingA tertiary hospital setting. ParticipantsA total of 185 patients with acute ischemic stroke, capable of walking 10 m with or without a gait aid by day 7 postadmission. From these patients, 10,804 pairs of consecutive footfalls were included for analysis. InterventionsNot applicable. Main Outcome MeasuresThe dependent variable was a 3-month poor functional outcome, defined as modified Rankin scale score ≥2. For independent variables, 65 clinical variables including demographics, anthropometrics, comorbidities, laboratory data, questionnaires, and drug history were included. Gait function was evaluated using a pressure-sensitive mat. Time-series COP data were parameterized into spatial and temporal variables and analyzed with logistic regression and 2 ML models (light gradient-boosting machine and multilayer perceptron [MLP]). We derived GAIT-AI output scores from the best-performing model analyzed COP data and constructed multivariable logistic regression models using clinical variables and the GAIT scores. ResultsAmong the included patients, 70 (37.8%) experienced unfavorable outcomes. The MLP model demonstrated the highest predictive performance with an area under the receiver operating characteristic curve (AUROC) of 0.799. Multivariable logistic regression identified age, initial National Institutes of Health Stroke Scale, and initial Fall Efficacy Scale-International as associated factors with unfavorable outcomes. The combined multivariable logistic regression incorporating COP-derived output scores improved the AUROC to 0.812. ConclusionsGait function, assessed through COP analysis, serves as a significant predictor of functional outcome in patients with acute ischemic stroke. ML-based COP analysis, when combined with clinical data, enhances the prediction of poor functional outcomes.

Balance Problems in the Elderly with Diabetes Mellitus: A Literature Review.

Diabetes mellitus (DM) is a syndrome of chronic metabolic disease which leads to all kinds of complications. Elderly people with DM have significantly higher fear of falling and balance problem scores as compared to those who did not have DM. This literature review aims: (1) to determine the risk factors for balance disorders in the elderly population with DM, (2) to describe valid and reliable balance measurement tools in the elderly population with DM, and (3) to describe the nonpharmacological management in dealing with balance disorders in the elderly population with DM. Several risk factors that cause balance disorders in the elderly with DM are related to complications of the disease they suffer, such as diabetic peripheral neuropathy, decreased sensory abilities, decreased motor skills, and decreased cognitive condition of the elderly with DM. Measuring instruments that can be used in the elderly population with DM to assess balance include the Mini-Balance Evaluation Systems Test, the Berg Balance Scale, and computerized measuring instruments with center of pressure analysis. Several nonpharmacological interventions are suggested in overcoming balance problems in the elderly with DM, including a combination of balance exercise and gait training, strength or resistance training, aquatic exercise, tai chi, yoga, technology-based exercise, electrotherapy, use of insoles, and whole-body vibrations.

A validation study to analyze the reliability of center of pressure data in static posturography in dogs.

Center of pressure (COP) parameters are frequently assessed to analyze movement disorders in humans and animals. Methodological discrepancies are a major concern when evaluating conflicting study results. This study aimed to assess the inter-observer reliability and test-retest reliability of body COP parameters including mediolateral and craniocaudal sway, total length, average speed and support surface in healthy dogs during quiet standing on a pressure plate. Additionally, it sought to determine the minimum number of trials and the shortest duration necessary for accurate COP assessment. Twelve clinically healthy dogs underwent three repeated trials, which were analyzed by three independent observers to evaluate inter-observer reliability. Test-retest reliability was assessed across the three trials per dog, each lasting 20 seconds (s). Selected 20 s measurements were analyzed in six different ways: 1 × 20 s, 1 × 15 s, 2 × 10 s, 4 × 5 s, 10 × 2 s, and 20 × 1 s. Results demonstrated excellent inter-observer reliability (ICC ≥ 0.93) for all COP parameters. However, only 5 s, 10 s, and 15 s measurements achieved the reliability threshold (ICC ≥ 0.60) for all evaluated parameters. The shortest repeatable durations were obtained from either two 5 s measurements or a single 10 s measurement. Most importantly, statistically significant differences were observed between the different measurement durations, which underlines the need to standardize measurement times in COP analysis. The results of this study aid scientists in implementing standardized methods, thereby easing comparisons across studies and enhancing the reliability and validity of research findings in veterinary medicine.

Distinctive phases and variability of vibration-induced postural reactions highlighted by center of pressure analysis

Distinctive phases and variability of vibration-induced postural reactions highlighted by center of pressure analysis

Why do children with unilateral cerebral palsy struggle with the single leg stance test? A kinematic and centre of pressure analysis

BackgroundChildren with unilateral cerebral palsy often report difficulty with balance in everyday life. The single leg stance test is a challenging task, requiring rapid sensory input and precise motor adjustment. The purpose of this study was to examine how children with cerebral palsy perform this test, compared to typically developing children. MethodsThree-dimensional kinematics of the trunk and lower limbs of 10 children with cerebral palsy and 15 children with typical development were captured as they performed a single leg stance test on their non-dominant leg on a force platform. Stance time, joint kinematics and centre of pressure sway were measured and examined. FindingsThere was evidence of shorter single leg stance performance and increased mediolateral centre of pressure sway in children with cerebral palsy. Coronal plane movement at the subtalar joint and foot was reduced (−6.0° (−10.9, −1.2°)), while proximally there was greater trunk movement in the coronal (13.5° (2.4°, 24.5°)) and transverse planes (9.9° (0.7, 19°)) and pelvis movement in the transverse plane (6.1° (1.7, 10.5°). An association existed between stance time and mediolateral centre of pressure sway (p < 0.01), with an average reduction in stance time of 0.15 s for every 1 mm/s increase in mediolateral sway. InterpretationChildren with cerebral palsy showed poor mediolateral control of centre of pressure sway, leading to shorter stance time. They have a less effective coronal foot-tilt strategy and excessive trunk and pelvis movement. Interventions aimed at improving single leg stance performance should consider addressing both ankle / foot and trunk motor control.

Distinctive phases and variability of vibration-induced postural reactions highlighted by center of pressure analysis.

The vibration-induced postural reaction paradigm (VIB-PR) offers a unique way for investigating sensorimotor control mechanisms. Measures of VIB-PR are usually calculated from the whole VIB period, yet recent evidence proposed that distinctive mechanisms are likely at play between the early vs. later phases of the postural reaction. The present work verified if spatiotemporal analyses of center of pressure (COP) displacements can detect differences between these early/later phases of VIB-PR. Also, we further characterized the intra/inter-individual variability of COP measurements, since the underlying variability of VIB-PR remains largely unexplored. Twenty young volunteers realized two experimental conditions of bipodal stance with eyes closed: (i) bilateral VIB of tibialis anterior (TIB) and (ii) Achilles' (ACH) tendons. Each condition consisted of five trials and lasted 30 s as follows: 10 s baseline, 10 s VIB and 10 s post-VIB. Linear COP variables (antero-posterior (AP) amplitude & velocity) were computed for both VIB and post-VIB periods using the following time-windows: early 2 s, the later 8 s and the whole 10 s duration. Intra- and inter-individual variability were respectively estimated using the standard error of the measurement and the coefficient of variation. Both variability metrics were obtained using five vs. the first three trials. Significant contrasts were found between time-windows for both VIB and post-VIB periods. COP variables were generally higher during the early 2 s phase compared to the later 8 s phase for both TIB [mean difference between 8 s- 2 s phases: Amplitude AP = -1.11 ± 1.14 cm during VIB and -2.99 ± 1.31 during post-VIB; Velocity AP = -1.17 ± 0.86 cm/s during VIB and -3.13 ± 1.31 cm/s during post-VIB] and ACH tendons [Amplitude AP = -0.37 ± 0.98 cm during VIB and -3.41 ± 1.20 during post-VIB; Velocity AP = -0.31 ± 0.59 cm/s during VIB and -3.89 ± 1.52 cm/s during post-VIB]. Most within- and between-subject variability scores were below 30% and using three instead of five trials had no impact on variability. VIB-PR patterns were quite similar within a same person, but variable behaviors were observed between individuals during the later phase. Our study highlights the relevance of identifying and separately analyzing distinct phases within VIB-PR patterns, as well as characterizing how these patterns vary at the individual level.

Effects of freezing of gait on balance in patients with Parkinson’s disease

ABSTRACT Objectives The aim of the study was to evaluate the effects of freezing of gait (FOG) on static and dynamic balance. Methods Twenty patients with Parkinson’s disease with and without FOG [PD+FOG (68,6±6,39 years) and PD-FOG group (70,6±4,57 years)] and 10 healthy individuals (68,4±4,92 years) with similar demographic characteristics were included in the study. Balance was compared between the three groups. Balance was evaluated with clinical tests Limits of stability (LoS) and body sway were measured using the E-LINK FP3 Force Plate and the Korebalance Balance Evaluation System, which measure the balance in static and dynamic conditions. Center of pressure (COP) change and average sway velocity were evaluated with the Zebris RehaWalk system. Results Total and subscale scores of the Unified Parkinson’s Disease Rating Scale were significantly higher in the PD+FOG group (p<0.05). The balance test results for both groups were similar (p>0.05). The PD+FOG group performed worse on the computerized static balance tests, the COP analysis, and the dynamic balance total score than the other two groups (p<0.05). The PD+FOG group had significantly greater sustained weight deviation than the healthy controls (p<0.05). Patients with Parkinson’s disease had a lower LoS in the posterior direction than healthy controls (p<0.05). Discussion FOG affects the dynamic balance more negatively than the static balance. In addition, FOG reduces LoS in the posterior direction and increases body sway in the anterior-posterior direction, which can lead to falls. Keywords Center of pressure, Freezing of gait, Limits of stability, Parkinson’s disease, Postural Balance.

Standing Posture in Motor and Cognitive Dual-Tasks during Smartphone Use: Linear and Nonlinear Analysis of Postural Control.

Analysis of the center of pressure (CoP) during cognitive or motor dual-tasking is widely used to characterize postural control. Most studies use traditional measures of CoP to quantify postural control, but given its complexity, nonlinear analysis of CoP is of growing interest in the area. This study aims to analyze CoP behavior in healthy young adults during standing posture performance while simultaneously performing motor or cognitive tasks on a smartphone, using linear and nonlinear analysis of CoP. Thirty-six healthy participants (23.08 ± 3.92 years) were found eligible for this study. They performed a single task (ST), cognitive dual-task (cog-DT), and motor dual-task (mot-DT). The total excursion of CoP, displacement of CoP in the anterior-posterior and medial-lateral directions, mean total velocity of CoP, and mean anterior-posterior and medial-lateral velocities of CoP were measured with a force plate. Approximate entropy (ApEn) of the anterior-posterior (ApEn-AP) and medial-lateral (ApEn-ML) displacement of CoP were also calculated. The results showed that dual-task costs for the total excursion, displacement in the anterior-posterior direction, mean total velocity, and mean anterior-posterior velocity of CoP were greater during the cog-DT than the mot-DT (p < 0.05). In the nonlinear analysis of the CoP, there was no difference (p > 0.05) between the cog-DT and mot-DT for ApEn values of the anterior-posterior and medial-lateral time series of the CoP. Both linear and nonlinear analyses showed differences between the cog-DT and ST (p < 0.05), revealing a decline in postural control during the cog-DT compared with the ST. In conclusion, performing a cog-DT causes sway impairments and lower postural control efficacy compared with motor single and dual-tasks. Furthermore, both linear and nonlinear analyses were able to distinguish between conditions.

Influence of Cognitive Task Difficulty in Postural Control and Hemodynamic Response in the Prefrontal Cortex during Static Postural Standing

In daily life, we perform several tasks simultaneously, and it is essential to have adequate postural control to succeed. Furthermore, when performing two or more tasks concurrently, changes in postural oscillation are expected due to the competition for the attentional resources. The aim of this study was to evaluate and compare the center of pressure (CoP) behavior and the hemodynamic response of the prefrontal cortex during static postural standing while performing cognitive tasks of increasing levels of difficulty on a smartphone in young adults. Participants were 35 healthy young adults (mean age ± SD = 22.91 ± 3.84 years). Postural control was assessed by the CoP analysis (total excursion of the CoP (TOTEX CoP), displacements of the CoP in medial–lateral (CoP-ML) and anterior–posterior (CoP-AP) directions, mean total velocity displacement of CoP (MVELO CoP), mean displacement velocity of CoP in medial–lateral (MVELO CoP-ML) and anterior–posterior (MVELO CoP-AP) directions, and 95% confidence ellipse sway area (CEA)), the hemodynamic response by the oxyhemoglobin ([oxy-Hb]), deoxyhemoglobin ([deoxy-Hb]), and total hemoglobin ([total-Hb]) concentrations using a force plate and functional near-infrared spectroscopy (fNIR), respectively. The results showed that the difficult cognitive task while performing static postural standing caused an increase in all CoP variables in analysis (p &lt; 0.05) and of [oxy-Hb] (p &lt; 0.05), [deoxy-Hb] (p &lt; 0.05) and [total-Hb] (p &lt; 0.05) compared to the postural task. In conclusion, the increase in the cognitive demands negatively affected the performance of the postural task when performing them concurrently, compared to the postural task alone. The difficult cognitive task while performing the postural task presented a greater influence on postural sway and activation of the prefrontal cortex than the postural task and the easy cognitive task.

TEST-RETEST RELIABILITY OF WAVELET-BASED SPECIFIC FREQUENCY BANDS OF POSTURAL CONTROL DURING TWO STANDING TASK CONDITIONS

Background: The evaluation of balance measures can help identify postural control processes, but traditional data collection for the center of pressure (COP) may not reveal differences in postural control mechanisms. This study aimed to evaluate the reliability of the frequency component of postural sway using wavelet analysis of COP signals.Methods: Fifteen healthy male subjects (average age: 39.16±7.2 years, average weight: 72±11.06 kg, average height: 171±6.31 cm) participated in this project. They were requested to perform three trials of single-leg and tandem stance conditions for 20-second with and without vision on a force plate. The frequency content of COP signals, including the energy, root mean square (RMS), and velocity of the COP in four frequency bandwidths of postural sway, was evaluated. The test-retest reliability of COP parameters was tested using the intraclass correlation coefficient (ICC).Results: Among different COP parameters, the energy of the COP within a moderate (1.56–6.25 Hz) frequency band (.79≤ ICC ≤.97) with standard error measurement (SEM) ranged from .14 to .23, the RMS of COP within low (.39–1.56Hz) (.79≤ ICC ≤.93) and ultralow (&lt; .10 Hz) (SEM ranged from .000 to .002) (.78≤ ICC ≤.94) in a tandem stance and the RMS of COP in a bandwidth of &lt; .10 Hz (SEM=.00) in a single-leg stance (.70≤ ICC ≤.99) with the eyes closed and open showed good to excellent reliability.Conclusion: The results of this study showed moderate to excellent reliability of wavelet-based COP measures; therefore, these parameters can be used for the identification of postural control mechanisms.

Temporo-spatial and kinetic gait parameters in English setter dogs.

Walking analysis systems have begun to be used in veterinary medicine in recent years. The pressure-sensitive walkway is one of the systems through which we can obtain temporo-spatial and kinetic variables of walking. Therefore, the aim of this study was to investigate the walking characteristics of English Setter dogs using a pressure-sensitive system. Twenty-five English Setter dogs were included in the study. Temporo-spatial and kinetic gait parameters were obtained with the pressure-sensitive walkway system. Centre of pressure values were taken separately for the forelimbs and hindlimbs and were statistically analysed. The force values in the forelimb were found to be greater than in the hindlimb during walking. According to the results of dynamic pedobarographic evaluation, the highest-pressure values were found at the 2nd and 3rd digital pads for the forelimbs and on the 3rd and 4th digital pads for the hindlimbs. During the stance, 64.58% of the weight was found to be on the forelimbs. No difference was found between the forelimbs and the hindlimbs in centre of pressure analysis. As conclusion, the gait data obtained from the English Setter dogs can be used in future research to identify animals that may have neurological or orthopaedic problems.

Multi-Exergames to Set Targets and Supplement the Intensified Conventional Balance Training in Patients With Stroke: A Randomized Pilot Trial

People who survive a stroke usually suffer movement disorders resulting in involuntary abnormal movements. Intensive and repetitive physiotherapy is often a key to functional restoration of movements. Rehabilitation centers have recently offered balance training supported by exergames in addition to conventional therapy. The primary objective was to investigate different types of balance training (multi-exergaming and conventional) in addition to a conventional 6-week physiotherapy program. Furthermore, we examined the choice of an appropriate exergame to target balance training. We designed a randomized pilot trial. Hospital inpatients with stroke aged 33–65 were recruited and randomized into 2 groups by drawing lots; a control group receiving 1 week of conventional balance training and an exergaming group 1 week of multiple-game exergaming, comprising single leg exercises, weight shifting, balancing and standing up. Center of pressure was monitored for the exergaming group and clinical data were collected (non-blinded assessment) using Four Square Step Test, Timed Up and Go, 10 m Walk Test, Romberg, Sharpened Romberg, Clinical Test for Sensory Interaction in Balance in both groups. Statistical tests were used to find significant (p < 0.05) differences and Cohen’s U3 for effect sizes. Recruited participants (20/30) met the inclusion criteria and were randomized; 10 per group. 1 participant of the exergaming group was excluded from center of pressure analysis. Both groups demonstrated substantively and statistically significant improvements of functional balance, in particular the exergaming group (FSST p = 0.009, U3 = 0.9 and 10 MWT p = 0.008, U3 = 0.9). However, significant differences between the groups were found in tests with eyes closed, Sharpened Romberg test (p = 0.05) and standing on the right leg (p = 0.035). The center of pressure area decreased up to 20% for the exergaming group. Both types of additional balance training demonstrated comparable outcomes, however, the multi-exergaming could target specific motor control disorders by the selection of exergames according to Gentile’s taxonomy. We may not prioritize exergaming due to the low statistical power of clinical outcomes. However, exergaming enables independent balance training, which is feasible without strenuous physiotherapy and may thus be crucial for future home or telerehabilitation services.Clinical Trial Registration: www.clinicaltrials.gov/, identifier NCT03282968.

Increased EEG alpha peak frequency in adolescents with idiopathic scoliosis during balance control in normal upright standing

Adolescent idiopathic scoliosis (AIS) is a multifactorial disorder characterized by a tridimensional deformation of the spine. AIS pathophysiology is still unclear and its aetiology is unknown. Results from several studies revealed balance control alterations in adolescents with AIS suggesting cortical sensorimotor processing impairments. Studies assessing cortical activity involved in balance control revealed an increase in alpha peak frequency (APF), which is a neurophysiological marker of thalamo-cortical transmission, related to a more challenging balance task. The objective of this study is to assess APF of adolescents with AIS during balance control in upright standing posture using electroencephalography (EEG). EEG was recorded in 16 girls with AIS and 15 control girls in normal standing posture on a force platform. The participants stood upright for 2 min with eyes open and 2 min with eyes closed. Fast Fourier transformations of EEG data were calculated to obtain APF. Balance performances were assessed through the area of an ellipse covering the center of pressure (COP) displacement and the root mean square value of the COP velocity. Compared to the control group, APF was higher in the AIS group at central, frontal, parietal and occipital regions. Further, COP analyses did not reveal any difference between AIS and control groups. A higher APF may indicate the need for increased cortical processing to maintain balance control in normal upright standing in adolescents with AIS compared to healthy controls. We suggest that this may be a compensatory strategy to overcome balance control challenges.

건강한 남녀노인의 정적자세 유지를 위한 압력중심 분석

The purpose of this study was to determine a relations with age and quiet standing stability of elderlies, and to compare a standing stability of female and male elderlies through a analysis of COP(center of pressure). Healthy female(n=10, age: 76.00±4.37) and male(n=10, age: 77.70±3.30) elderlies participated for this project. The measurement was processed each distance and 95% confidence ellipse area of COP in those variations undergoing comfortable quiet upright standing with term interval 5 seconds, 6 sections, and overall 30 seconds. Correlation of Spearman analysis was performed age with COP factors by Pearson in two ways. Independent sample t-test was practiced for the comparison of female and male elderly groups with statistical significant level of .05. Significant result was not appeared in correlation age with factors such as distance and area. Female elderly group had a greater COP sways of distance and area than male elderly group during quiet upright standing, and COP distance offering significant data in terms of 0~5s, 6~10s, 16~20s, 21~25s. Standard Deviation(SD) data of female elderly group were greater than male elderly group over all of 5sec terms in COP distance and area. All of participants need the times(0~15s) for adapting of the initial stability posture, they showed decreasing of sways and firm stabilities since then. In conclusion, Stability of standing posture in elderlies can vary as the health and fitness condition of them. In other words, age is not the only balance decreasing factor in physical. And ability of upright standing from each individual had a wide gap in female elderly group. Female elderlies have more sways than male elderlies in stability posture, some intervention of prevent fall is demanded for female elderlies such as a specific balance program.

Development of a Novel Gait Analysis Tool Measuring Center of Pressure for Evaluation of Canine Chronic Thoracolumbar Spinal Cord Injury

Gait evaluation after spinal cord injury (SCI) is an important component of determining functional status. Analysis of center of pressure (COP) provides a dynamic reflection of global locomotion and postural control and has been used to quantify various gait abnormalities. We hypothesized that COP variability would be greater for SCI versus normal dogs and that COP would be able to differentiate varying injury severity. Our objective was to investigate COP, COP variability, and body weight support percentage in dogs with chronic SCI. Eleven chronically non-ambulatory dogs after acute severe thoracolumbar SCI were enrolled. COP measurements in x (right-to-left, COPx) and y (craniocaudal, COPy) directions were captured while dogs walked on a pressure-sensitive treadmill with pelvic limb sling support. Root mean square values (RMS_COPx and RMS_COPy) were calculated to assess variability in COP. Body weight support percentage was measured using a load cell. Gait also was quantified using an open field scale (OFS) and treadmill-based stepping and coordination scores (SS, RI). Mean COPx, COPy, RMS_COPx, and RMS_COPy were compared between dogs with SCI and previously evaluated healthy controls. RMS measurements and support percentage were compared with standard gait scales (OFS, SS, RI). Mean COPy was more cranial and RMS_COPx and RMS_COPy were greater in SCI versus normal dogs (p < 0.001). Support percentage moderately correlated with SS (p = 0.019; R2 = 0.47). COP analysis and body weight support measurements offer information about post-injury locomotion. Further development is needed before consideration as an outcome measure to complement validated gait analysis methods in dogs with SCI.

Effectiveness of functional electrical stimulation of gait. Evaluating of modifications to the center of pressure for a hemiparetic patient

Drop foot is the principal ambulatory anomaly impacting hemiplegic patients. The effectiveness of Functional Electric Stimulation (FES) on gait parameters in hemiplegics has been demonstrated over the medium and long term. Clinical evaluation of this setup and its’ effectiveness is not always easy; changes in gait parameters being difficult to measure solely by observation. Ideally, the application of FES should be done along with a 3-D analysis of the patient's gait, which can be a time-consuming procedure. The goal of this study is to evaluate dynamic changes in the center of pressure (COP), measured using an instrumented walkway, when applying FES. A mono-paretic patient, stable after frontal tumor surgery, was treated with FES of the fibularis communis nerve. The evaluation of gait, at a comfortable walking pace, was realized using an analysis of both spatio-temporal parameters and COP, obtained using the GAITRite walkway. The evaluation was conducted, immediately before and after application of FES. Spatio-temporal gait parameters (walking speed, stride length, cadence) were not modified by FES. Our analysis confirms an immediate ‘posteriorization’ of the COP upon initial application of FES. Net postero-anterior displacement of the COP was increased by FES. This study confirms the findings in the referenced literature, where during same-day evaluation, FES is shown to not modify spatio-temporal parameters. These modifications only being manifest during prolonged use. We observed changes in the net displacement of the COP on initial application of FES. This corroborates a recent study, which suggests that FES could have an immediate effect on weight transfer and thus increase gait stability. The evaluation of the displacement in the COP could represent a readily observable parameter in gauging the effectiveness of FES when applied to patients with drop-foot. This parameter could be easily and objectively measured with available tools such as an instrumented walkway.

The effect of unilateral balance training on postural control of the contralateral limb

ABSTRACTTo investigate the impact of unilateral balance training on postural control of the trained and contralateral limb in healthy elderly. Fifty-one healthy old adults were randomly assigned into training group (TG) and control group (CG). Participants of the TG performed unilateral balance training (dominant (DOM) leg) over 4 weeks (4×/week). Centre of pressure analysis was performed at baseline, 5 weeks follow-up and 9 weeks follow-up under the following conditions: (1) one-leg stance without additional task, (2) one-leg stance with motor task and (3) one-leg stance with cognitive task. From baseline to 5 weeks follow-up, a mixed analysis of variance detected a significant time × group interaction for the DOM leg (P < 0.05), indicating higher improvement of the TG in comparison to CG. No significant interaction effect was found for the non-DOM leg. Within the TG, the non-DOM leg significantly improved in mean velocity (P = 0.001) and anterior–posterior range (P < 0.001). Unilateral balance training was effective to improve postural control of the trained leg. The effect on the contralateral leg was small and not significant within this study design. Improvements were retained after 4 weeks without training. A tendency is given that unilateral balance training might be beneficial to improve postural control of the contralateral leg.

Visual transparent & visual occlusion: An EEG and COP study.

Electroencephalography (EEG) and centre of pressure (COP) data were recorded in young adults for 60 seconds during standing in visual transparent (VT) and visual occlusion (VO) conditions. In both of these conditions, participants wore VO liquid crystal spectacles which allowed the experimenter to accurately control visual information being presented or occluded to the participant. Alpha band (8-13 Hz) revealed significant differences in channel-averaged power spectrum in these two conditions, but not theta band (4-8 Hz) and beta band (13-30 Hz). In order to determine which channels contributed to these bands, region-averaged and single-channel power spectrum were computed which revealed similar patterns for eyes-open (VT) and eyes-closed (VO) conditions in each band. COP analysis was performed to understand postural steadiness in VT and VO conditions; the analysis indicated significant and larger time-domain distance measures (mean velocity), time-domain hybrid measures (mean frequency and sway area) and frequency domain measures (centroidal frequency) in the VO condition. The increased of alpha power in most frontal and posterior regions was indicative of the cortical processing of vision.

The Contribution of Hearing and Hearing Loss to Balance Control

This study investigated the hypothesis that a hearing ‘map' of our surroundings is used to maintain balance control. We investigated the effects of sound on postural sway using centre of pressure analysis in 50 subjects with normal hearing, 28 with hearing loss and 19 with vestibular dysfunction. The acoustic environments utilized sound cues that were either present or absent. It was found that auditory cues are utilized by subjects with normal hearing to improve postural sway. The ability to utilize sound for postural control is diminished when there is a hearing loss, but this appears to be overcome by the use of a hearing aid. Patients with additional vestibular deficits exploit auditory cues to a greater degree, suggesting that sensory weighting to enhance the use of auditory cues may be applied when there is diminished sensory redundancy.

The relationship of ankle and foot kinematics with knee loading and foot center of pressure responses to a flexible footwear intervention

Purpose: Flexible footwear has been associated with reduction of the knee adduction moment (KAM), an indicator dynamic medial knee loading. The mechanisms underlying this reduction, although unclear, may be in part through medialization of the foot center of pressure (COP), which has been associated with reduction in the KAM. Likewise, ankle and foot kinematics likely influence these relationships. Here, we evaluate the association of detailed foot kinematics with the response of knee loading and foot COP to a flexible footwear intervention. Methods: Participants with symptomatic medial compartment knee OA (KL 2 and 3) were evaluated at baseline using simultaneous barefoot COP analyses and 3-D gait analyses which included detailed foot kinematic modeling. All participants were provided flexible shoes (Dr. Comfort Flex-OA, Mequon, WI) and instructed to wear them at least 6 hours/day, 6 days/week. Gait and COP analyses were repeated after 12 and 24 weeks of wearing the shoes. Gait testing consisted of five trials each while barefoot, in subjects “own shoe”, and in the flexible shoe. During barefoot trials, plantar pressure distribution was acquired simultaneously by mounting a pressure platform onto a force plate and leveling the stacked assembly with the walkway. COP was quantified by determining the Medial to Lateral Pressure Index (MLPI), normalized to foot width. Paired samples t-tests were used to evaluate changes in KAM and foot COP. Spearman correlations were used to evaluate the association between KAM reduction and medialization of foot COP over 24 weeks with baseline foot kinematics as well as the change in kinematics after 24 weeks of wearing flexible shoes. Results: 28 participants were evaluated (mean age 59±7 years, 21 women). At 24 weeks, the KAM in the flexible shoe was reduced compared with their own shoes (2.88±0.99 vs 2.73±0.81%BW*Ht, p=0.030). Overall there did not appear to be significant medialization in foot COP and medialization was not related to KAM reduction. Reduction in KAM after 24 weeks was directly associated with overall range from foot supination to pronation during barefoot walking at baseline (rho=0.426, p=0.024) and flatter foot as measured by maximal medial arch angle after 24 weeks of wearing flexible shoes (rho=0.472, p=0.023). Medialization in foot COP after 24 weeks was directly associated with more maximal forefoot supination during barefoot walking at baseline (rho=0.405,p=0.036) and more rearfoot eversion by 24 weeks (rho=0.506, p=0.012). Conclusions: These results suggest that ankle and foot kinematic factors rather than medialization of foot COP are responsible for reducing medial knee loading with flexible footwear. Overall foot mobility during walking, in particular forefoot supination and pronation as well as lower medial arch by 24 weeks was associated with greater medial knee load reduction with use of flexible footwear. In contrast, medialization of foot COP alone did not affect medial knee loading. Other related foot kinematic variables including extent of forefoot supination and more rearfoot eversion were related to medialization in foot COP. This study demonstrates that dynamic foot kinematics are related to knee loading responses and plantar pressure changes with use of flexible footwear.