Mediolateral Center Of Pressure Displacement Research Articles

Influences of cognitive load on center of pressure trajectory of young male adults with excess weight during gait initiation.

Introduction: Falls and fall-related injuries in young male adults with excess weight are closely related to an increased cognitive load. Previous research mainly focuses on analyzing the postural control status of these populations performing cognitive tasks while stabilized walking progress but overlooked a specific period of walking known as gait initiation (GI). It is yet unknown the influences of cognitive load on this population's postural control status during GI. Objective: This study aimed to determine the influences of cognitive load on the center of pressure (CoP) trajectory of young male adults with excess weight during GI. Design: A controlled laboratory study. Methods: Thirty-six male undergraduate students were recruited and divided into normal-weight, overweight, and obese groups based on their body mass index (BMI). Participants' CoP parameters during GI under single and dual-task conditions were collected by two force platforms. A mixed ANOVA was utilized to detect significant differences. Results: Compared with the normal-weight group, the obese group showed significant changes in the duration and CoP parameters during sub-phases of GI, mainly reflecting prolonged duration, increased CoP path length, higher mediolateral CoP displacement amplitude, and decreased velocity of anteroposterior CoP displacement. During GI with 1-back task, significantly increased mediolateral CoP displacement amplitude occurred in the obese group. During GI with 2-back task, the obese group had increased CoP path length, higher mediolateral CoP displacement amplitude, as well as a decreased velocity of CoP displacement. Conclusion: Based on the changes in CoP parameters during GI with cognitive tasks, young male adults with excess weight, mainly obese ones, have compromised postural stability. During GI with a difficult cognitive task, obese young male adults are more susceptible to deterioration in their lateral postural balance. These findings indicate that the increased cognitive load could exacerbate obese young male adults' postural control difficulty during GI under dual-task conditions, putting them at a higher risk of experiencing incidents of falls. Based on these findings, we offer suggestions for therapists to intervene with these young male adults to ensure their safety of GI.

External mechanical perturbations challenge postural stability in dogs.

This study aimed to explore the effect of external mechanical perturbations on postural stability (PS) in dogs using the body center of pressure (COP). Thirteen sound adult dogs were included in this study. PS was tested during quiet standing on a pressure measurement plate. The conditions included a standard standing measurement and external mechanical perturbations conducted using six settings on a motorized training platform with different intensities of speed and amplitude. Measurement conditions were compared using linear mixed-effects models, followed by multiple comparisons using Sidak's alpha correction procedure. Compared with the standing measurement, external mechanical perturbations resulted in a significant increase in almost all COP parameters, indicating a challenge for the PS. Furthermore, an increase in amplitude had a greater effect than an increase in speed, whereas the combination of the highest intensities of amplitude and speed was not well tolerated by the dogs. The mediolateral COP displacement was significantly greater than the craniocaudal COP displacement during standing measurement and conditions with a small amplitude, whereas no significant difference was observed during settings with an increased amplitude. To the best of our knowledge, this is the first study to demonstrate the effects of a balance training device in dogs. Therefore, the intensity of the training programs on motorized platforms or similar devices can be controlled by the wobbling amplitude of the platform.

Reliability of unconventional centre of pressure measures of quiet standing balance in people with chronic stroke

BackgroundPeople with stroke often have asymmetric motor impairment. Investigating asymmetries in, and dynamic properties of, centre of pressure movement during quiet standing can inform how balance is controlled. Research questionWhat are the test-retest reliabilities of unconventional measures of quiet standing balance control in people with chronic stroke? MethodsTwenty people with chronic stroke (>6 months post-stroke), who were able to stand for at least 30 s without support, were recruited. Participants completed two 30-second quiet standing trials in a standardized position. Unconventional measures of quiet standing balance control included: symmetry of variability in centre of pressure displacement and velocity, between-limb synchronization, and sample entropy. Root mean square of centre of pressure displacement and velocity in the antero-posterior and medio-lateral directions were also calculated. Intraclass correlation coefficients (ICCs) were used to determine test-retest reliability, and Bland-Altman plots were created to examine proportional biases. ResultsICC3,2 were between 0.79 and 0.95 for all variables, indicating ‘good’ to ‘excellent’ reliability (>0.75). However, ICC3,1 for symmetry indices and between-limb synchronization were < 0.75. Bland-Altman plots revealed possible proportional biases for root mean square of medio-lateral centre of pressure displacement and velocity and between-limb synchronization, with larger between-trial differences for participants with worse values. SignificanceThese findings suggest that centre of pressure measures extracted from a single 30-second quiet standing trial may have sufficient reliability for some research studies in chronic stroke. However, for clinical applications, the average of at least two trials may be required.

POSTURAL CONTROL DURING MOTOR DUAL-TASK IN YOUNG ADULTS WITH DIFFERENT LEVELS OF PHYSICAL ACTIVITY

Introduction: Center of pressure (CoP) is an objective measure to assess postural control. A higher displacement of the CoP position can express a decline in postural control. Previous studies have demonstrated that a sedentary lifestyle affects balance negatively and increases the risk of falling. In addition, most activities of daily living involve performing two or more tasks concurrently. Thus, while performing a dual or multi-tasks, it is essential to maintain an adequate postural control to prevent the risk of falls and injuries. Objective: The main goal of this study was to compare the center of pressure displacement between healthy young adults with different levels of physical activity during motor dual-task performance. Method: After checking eligibility criteria, 35 healthy young adults (23.09 ± 3.97 years, mean ± SD) were recruited to perform a motor dual-task: maintaining quiet upright standing posture while performing a concurrent motor task – answer the smartphone, during 60 s. The total excursion of the center of pressure (TOTEX_CoP), the displacement anterior-posterior (CoP-AP), and medial-lateral (CoP-ML) of the center of pressure were recorded by Bertec® force plate, and the data was assessed with a Matlab routine. To analyze center of pressure excursions in different levels of physical activity, the International Physical Activity Questionnaire (IPAQ) – short version was used to assess physical activity levels. Then, the participants were divided into three groups: sedentary (n=5), minimally active (n=13), and highly active (n=17). Statistical analyses were performed using IBM-SPSS (version 25.0). To compare center of pressure displacement between different levels of physical activity during motor dual-task was used the Kruskal-Wallis test. The significance level was set at p &amp;lt; 0.05, and the data were shown as the median and interquartile range (IQR). Results: A tendency for a higher total displacement of the center of pressure was observed in the sedentary group (TOTEX_CoP: 3110.67 (2466.54-3908.73) mm) compared to the physically active groups (minimally active - TOTEX_CoP: 2600.75 (2500.34-3205.97) mm; highly active - TOTEX_CoP: 2712.99 (2499.01-3275.84) mm), but differences were not statistically significant between the three groups (p &amp;gt; 0.05). The same happened in the anteroposterior and mediolateral center of pressure displacement (p &amp;gt; 0.05). Conclusions: Physically active young adults did not present less postural oscillation than sedentary young adults during motor dual-task performance. The small sample in each physical activity group could have contributed to the lack of statistical significance. Therefore, we suggest more studies that assess the influence of the level of physical activity on postural control.

Postural control in adolescent boys and girls before the age of peak height velocity: Effects of task difficulty

BackgroundAdolescent children experience a critical developmental period marked by rapid biological changes.Research questionTo describe the longitudinal changes in postural control that occur in adolescent boys and girls before the age of peak height velocity (PHV). MethodsHere, to address the gap of knowledge, we compared the postural control and activation strategies of the muscles that control the ankle joint in twenty-three boys (age 12.5 ± 0.29) and twenty-one girls (age 10.5 ± 0.32). They performed easy (two legs) and difficult (two legs-eyes closed; one leg) postural balance tasks at 18 and 9 months before PHV and at PHV. We quantified the center of pressure (COP) displacements in the anterior-posterior (AP) and mediolateral (ML) directions and electromyographic (EMG) activity of tibialis anterior (TA) and medial gastrocnemius (MG) muscles. ResultsBoys exhibited greater AP and ML COP displacement than girls only for the one leg task (difficult task). Although boys and girls had similar postural control 18 months prior to PHV, girls exhibited lesser COP displacement at 9 months before PHV, which related to greater TA-MG coactivation (R2 = 0.26; p < 0.01). In contrast, postural control was not different between boys and girls with an easy balance task (two legs) performed with eyes open and closed. Rather, we found that all children improved their COP displacement in the ML direction with maturity and both AP and ML COP was significantly lower with eyes open. ConclusionThese findings provide novel evidence that postural control is superior in early adolescent girls than boys 9 months prior to PHV, likely associated with an earlier maturation of muscle coordination.

Effects of load carrying techniques on gait parameters, dynamic balance, and physiological parameters during a manual material handling task

PurposeSince construction workers often need to carry various types of loads in their daily routine, they are at risk of sustaining musculoskeletal injuries. Additionally, carrying a load during walking may disturb their walking balance and lead to fall injuries among construction workers. Different load carrying techniques may also cause different extents of physical exertion. Therefore, the purpose of this paper is to examine the effects of different load-carrying techniques on gait parameters, dynamic balance, and physiological parameters in asymptomatic individuals on both stable and unstable surfaces.Design/methodology/approachFifteen asymptomatic male participants (mean age: 31.5 ± 2.6 years) walked along an 8-m walkway on flat and foam surfaces with and without a load thrice using three different techniques (e.g. load carriage on the head, on the dominant shoulder, and in both hands). Temporal gait parameters (e.g. gait speed, cadence, and double support time), gait symmetry (e.g. step time, stance time, and swing time symmetry), and dynamic balance parameters [e.g. anteroposterior and mediolateral center of pressure (CoP) displacement, and CoP velocity] were evaluated. Additionally, the heart rate (HR) and electrodermal activity (EDA) was assessed to estimate physiological parameters.FindingsThe gait speed was significantly higher when the load was carried in both hands compared to other techniques (Hand load, 1.02 ms vs Head load, 0.82 ms vs Shoulder load, 0.78 ms). Stride frequency was significantly decreased during load carrying on the head than the load in both hands (46.5 vs 51.7 strides/m). Step, stance, and swing time symmetry were significantly poorer during load carrying on the shoulder than the load in both hands (Step time symmetry ration, 1.10 vs 1.04; Stance time symmetry ratio, 1.11 vs 1.05; Swing time symmetry ratio, 1.11 vs 1.04). The anteroposterior (Shoulder load, 17.47 mm vs Head load, 21.10 mm vs Hand load, −5.10 mm) and mediolateral CoP displacements (Shoulder load, −0.57 mm vs Head load, −1.53 mm vs Hand load, −3.37 ms) significantly increased during load carrying on the shoulder or head compared to a load in both hands. The HR (Head load, 85.2 beats/m vs Shoulder load, 77.5 beats/m vs No load, 69.5 beats/m) and EDA (Hand load, 14.0 µS vs Head load, 14.3 µS vs Shoulder load, 14.1 µS vs No load, 9.0 µS) were significantly larger during load carrying than no load.Research limitations/implicationsThe findings suggest that carrying loads in both hands yields better gait symmetry and dynamic balance than carrying loads on the dominant shoulder or head. Construction managers/instructors should recommend construction workers to carry loads in both hands to improve their gait symmetry and dynamic balance and to lower their risk of falls.Practical implicationsThe potential changes in gait and balance parameters during various load carrying methods will aid the assessment of fall risk in construction workers during loaded walking. Wearable insole sensors that monitor gait and balance in real-time would enable safety managers to identify workers who are at risk of falling during load carriage due to various reasons (e.g. physical exertion, improper carrying techniques, fatigue). Such technology can also empower them to take the necessary steps to prevent falls.Originality/valueThis is the first study to use wearable insole sensors and a photoplethysmography device to assess the impacts of various load carrying approaches on gait parameters, dynamic balance, and physiological measures (i.e. HR and EDA) while walking on stable and unstable terrains.

Gross motor dysfunction and balance impairments in children and adolescents with Down syndrome: a systematic review.

Background Individuals with Down syndrome present with several impairments such as hypotonia, ligament laxity, decreased muscle strength, insufficient muscular cocontraction, inadequate postural control, and disturbed proprioception. These factors are responsible for the developmental challenges faced by children with Down syndrome. These individuals also present with balance dysfunctions.Purpose This systematic review aims to describe the motor dysfunction and balance impairments in children and adolescents with Down syndrome.Methods We searched the Scopus, ScienceDirect, MEDLINE, Wiley, and EBSCO databases for observational studies evaluating the motor abilities and balance performance in individuals with Down syndrome. The review was registered on PROSPERO.Results A total of 1,096 articles were retrieved; after careful screening and scrutinizing against the inclusion and exclusion criteria, 10 articles were included in the review. Overall, the children and adolescents with Down syndrome showed delays and dysfunction in performing various activities such as sitting, pulling to stand, standing, and walking. They also presented with compensatory mechanisms to maintain their equilibrium in static and dynamic activities.Conclusion The motor development of children with Down syndrome is significantly delayed due to structural differences in the brain. These individuals have inefficient compensatory strategies like increasing step width, increasing frequency of mediolateral center of pressure displacement, decreasing anteroposterior displacement, increasing trunk stiffness, and increasing posterior trunk displacement to maintain equilibrium. Down syndrome presents with interindividual variations; therefore, a thorough evaluation is required before a structured intervention is developed to improve motor and balance dysfunction.

Development of postural stability in children with autism spectrum disorder: a cross-sectional study

ABSTRACT The purpose was to investigate the effects of age on postural stability for children with autism spectrum disorder (ASD). Twenty-nine children with mild ASD were assigned into one of the three groups: 6–8 years (U8), 9–11 years (U11) and 12–14 years (U14). Participants stood barefoot with both feet on a force platform and maintained stationary for 15 seconds during eyes-open and eyes-closed conditions. Center of pressure data were collected and variables were calculated, including displacements, total distances, sway areas, and sample entropy. The variables were compared among the three groups using a mixed-model ANOVA. The age group effect was significant for mediolateral center of pressure displacement (p = 0.04) and sway distance (p = 0.02). Post-hoc comparisons revealed that U8 exhibited greater mediolateral displacement and total distance compared to U14, regardless of test conditions. The U14 group exhibited improved mediolateral postural stability compared to U8, whereas no differences were found between U8 and U11 or between U11 and U14. This may suggest that children with ASD could slowly develop postural stability but only demonstrate significant changes over a long period of time. Early intervention programs aimed to improve complexity of postural control could be beneficial.

A systematic review of center of pressure measures to quantify gait changes in older adults.

Measures of gait center of pressure (COP) can be recorded using simple available technologies in clinical settings and thus can be used to characterize gait quality in older adults and its relationship to falls. The aim of this systematic review was to investigate the association between measures of gait COP and aging and falls. A comprehensive search of electronic databases including MEDLINE, Embase, Cochrane Central Register of Controlled Trials, CINAHL (EBSCO), Ageline (EBSCO) and Scopus was performed. The initial search yielded 2809 papers. After removing duplicates and applying study inclusion/exclusion criteria, 34 papers were included in the review. Gait COP has been examined during three tasks: normal walking, gait initiation, and obstacle negotiation. The majority of studies examined mean COP position and velocity as outcome measures. Overall, gait in older adults was characterized by more medial COP trajectory in normal walking and lower average anterior-posterior and medio-lateral COP displacements and velocity in both gait initiation and obstacle crossing. Moreover, findings suggest that Tai chi training can enhance older adults' balance control during gait initiation as demonstrated by greater COP backward, medial and forward shift in all three phases of gait initiation. These findings should be interpreted cautiously due to inadequacy of evidence as well as methodological limitations of the studies such as small sample size, limited numbers of 'fallers', lack of a control group, and lack of interpretation of COP outcomes with respect to fall risk. COP measures can be adopted to assess fall-related gait changes in older adults but more complex measures of COP that reveal the dynamic nature of COP behavior in step-to-step variations are needed to adequately characterize gait changes in older adults.

Abdominal muscle activity and pelvic motion according to active straight leg raising test results in adults with and without chronic low back pain

BackgroundActive Straight Leg Raise (ASLR) is a clinical test that challenges lumbopelvic stability and have been used in low back pain patients. There are reports of positive tests in asymptomatic individuals, however, it is not clear if they are false positives or a consequence of performing the test differently. ObjectivesTo compare abdominal muscles activity and pelvic motion during an ASLR between adults with chronic low back pain and asymptomatic participants with a positive and negative ASLR test. DesignCross-sectional study design. MethodNineteen volunteers with chronic nonspecific low back pain (LBP) and 19 asymptomatic, 12 with a negative ASLR (AG-) and 7 with a positive ASLR test (AG+) were assessed while performing an ASLR (dynamic postural challenge). Pelvic rotation and medio-lateral center of pressure displacement (COPml), as well as bilateral EMG abdominal muscles activity were assessed. Muscles asymmetry index were also analyzed. Kruskal-wallis test was used to compare groups (α = 0.05). ResultsBoth LBP and AG + displayed significantly less contralateral internal oblique/transversus abdominis (IO/TrA) muscle activation than AG- (p = 0.003 and p = 0.005, respectively) and also more asymmetry between sides in the IO/TrA than AG- (p = 0.022 and p = 0.004, respectively). No significant differences between LBP and AG+ were found (p > 0.05). ConclusionA positive ASLR test in an asymptomatic person could be more than a false positive, since IO/TrA muscle activation appears to be lower and more asymmetrical in people with a positive ASLR test, both with and without low back pain. Future studies may consider removing asymptomatic individuals with a positive ASLR.

Center of Pressure in the Paws of Clinically Sound Dogs in Comparison with Orthopedically Diseased Dogs

Simple SummaryThe analysis of the center of pressure is an important tool that allows conclusions to be drawn about the body balance of a patient. This balance can be altered by orthopedic or neurological diseases. To date, there are few data on the center of pressure in the paws of walking dogs. This study aimed to show the compensatory changes in the center of pressure parameters within the paw during stance-phase in the walking dog, with data being collected non-invasively by walking dogs with osteoarthritis and healthy dogs (control group) over a pressure platform. Differences in the center of pressure parameters were found between the affected and non-affected limbs of the diseased dogs, but also in comparison to the corresponding limbs of sound dogs. It was shown that dogs with osteoarthritis show different compensatory changes in the center of pressure parameters depending on whether a front or a hind limb are affected. This can reflect a compensatory redistribution of the body mass as well as compensatory changes of body balance. Based on these observations, a deeper investigation of the center of pressure within the paws of dogs would be of interest and a diagnostic application could become possible in the future.The center of pressure (COP) is recognized as a valuable tool for the assessment of orthopedic and neurologic disorders in humans. Relatively few studies are available in veterinary medicine, particularly concerning the COP in the individual paw. This study assessed the dynamic paw COP parameters during the stance phase of dogs with cox- or cubarthrosis (20 dogs each), as well as of 20 sound dogs. Data were obtained by walking over a pressure platform and analyzed within the diseased groups in comparison to the control group. Both diseased groups showed significant differences between the affected and non-affected limbs, but also in comparison to the reference limbs of sound animals. For coxathrosis, the primary increase was in the medio-lateral COP displacement and the COP area in both hind limbs. For cubarthrosis, the most prominent changes were an increase in the medio-lateral COP displacement in the ipsilateral hind limb and in the cranio-caudal COP displacement in the lame limb. Additionally, the COP area increased in both hind limbs. This can reflect a compensatory redistribution of the body mass as well as compensatory changes of body balance.

Head and neck extension more than 30° may disturb standing balance in healthy older adults

Although there is clinical evidence of postural instability at extreme angles of head extension, the effects of lower angles on balance have been not investigated. This study aimed to investigate the effects of different head and neck extension angles on standing balance in older adults, and to determine the critical angle of instability. Twenty-eight healthy older adults were tested at 0°, 20°, 30° and 40° head and neck extension. The center of pressure (COP) parameters were recorded with a force plate. Significant differences were observed between 30° and 40° compared to 0° in anteroposterior and mediolateral COP displacement and total COP velocity, and between 40° and 0° in mediolateral COP velocity. Head and neck extension at 30° was the critical angle associated with the appearance of instability, and this value should be considered in the ergonomic design of work and living spaces, exercise programming and daily activities in older adults.

Biomechanical Study of Tandem Stance in Healthy Young Adults: Effects of Weight-Bearing and Limb Dominance

Postural strategies of healthy young adults to control tandem stance were investigated through the calculation of the relative contribution of the two loading-unloading (LU) and pressure-distribution (PD) mechanisms and the two legs for controlling the resultant center-of-pressure (CPRes) displacements. Weight-bearing asymmetry and limb dominance were also studied. For antero-posterior and medio-lateral CPRes displacements, LU and PD mechanisms mainly contribute, respectively. A significant LU contribution is nonetheless observed for medio-lateral control, due to a lateral gap between the CP positions under each foot despite a strict sagittal alignment for the two feet. Moreover, for medio-lateral control, the respective involvement of the two legs is related to the level of weight-bearing asymmetry, whereas the front leg mainly controls the antero-posterior sway. By specifying potential effects of body-weight asymmetry and limb dominance, to a better testing of patients with deficiencies in lateral sway control.

Pressure biofeedback unit to assess and train lumbopelvic stability in supine individuals with chronic low back pain.

[Purpose] To determine if pressure biofeedback unit readings are related to abdominal muscle activation and centre of pressure displacement as well as to test the effects of using it as a biofeedback tool to control lumbopelvic motion. [Participants and Methods] Eighteen volunteers with chronic nonspecific low back pain (21.28 ± 1.41 years old) who performed an active straight leg raising (dynamic postural challenge) with and without pressure biofeedback. Changes in the pressure biofeedback unit and on centre of pressure displacement were assessed, as well as bilateral electromyographic abdominal muscle activity. Participants were not allowed to use a Valsalva manoeuvre. [Results] Pressure variation was not significantly correlated with abdominal muscle activity or with mediolateral centre of pressure displacement. When used as a biofeedback instrument, there was a significant increase in almost all abdominal muscles activity as well as a significant decrease in pressure variation and in mediolateral centre of pressure displacement while performing an active straight leg raising with a normal breathing pattern. [Conclusion] Despite not being an indicator of abdominal muscle activity or mediolateral load transfer in the supine position, the pressure biofeedback unit could have great relevance when used in the clinic for biofeedback purposes in individuals with low back pain.

Dynamical Indicators of Resilience in Postural Balance Time Series Are Related to Successful Aging in High-Functioning Older Adults.

Finding ways to quantify resilience as a predictor of a person's resistance to health challenges is important to improve healthy aging. This study investigated a unique sample of high-functioning older persons in whom traditional markers of frailty and functional decline are largely absent. Translating complex dynamical systems theory to humans, dynamical indicators of resilience in postural balance time series may sensitively discriminate levels of resilience. This study investigated 240 high-functioning older adults (mean age 83.9 ± 2.9 years, 59% male), of whom 94 hikers of the Nijmegen Four Days Marches. Participants stood upright on a force plate with eyes open and feet at shoulder width for 30 seconds. Center of pressure data were analyzed for dynamical indicators of resilience (variance and temporal autocorrelation). After 1 year, participants were compared on a modified Successful Aging Index. Mediolateral center of pressure displacement of hikers exhibited significantly lower variance (2.2 vs 2.8 mm, p < .001) and temporal autocorrelation (0.59 vs 0.65, p = .006), compared with nonhikers. Multivariably adjusted, mediolateral variance was significantly associated with successful aging at baseline (b = -1.43, p = .003) and 1-year follow-up (b = -1.94, p < .001), while mediolateral temporal autocorrelation was not. Two dynamical indicators of resilience (variance and temporal autocorrelation) calculated on time series of mediolateral center of pressure displacement differed between hikers and nonhikers within a group of high-functioning older adults. In the whole group, variance was independently associated with successful aging at baseline and after 1 year. Our results support the hypothesis that resilience of older persons may be estimated from time series of natural fluctuations of bodily functions.

The effect of Kinesio Taping on balance and foot arching in children with intellectual disability

ABSTRACTBackground: Assess the Kinesio Taping (KT) effect on balance and foot arches.Methods: Thirty young people with intellectual disability (ID) and flat feet were randomly assigned to experimental (E) and control (C) groups. Group E had KT applied to the sole of their feet and both groups participated in a 12-week task-oriented training conducted three times a week. Balance and foot arches were tested on a baroresistive platform before and after the study.Results: Enhanced balance was found in both groups. Group E had more balanced posture in the medio-lateral center of pressure displacement on eyes closed and in the anterior-posterior center of pressure displacement on eyes open tests than group C. Higher foot arches were discovered in both groups. In two participants in group E, the left foot arch changed from flat to normal.Conclusions: KT may valuably supplement therapeutic programs improving the sense of stability and creating proper foot structure in children with ID.

Effectively Quantifying the Performance of Lower-Limb Exoskeletons Over a Range of Walking Conditions.

Exoskeletons and other wearable robotic devices have a wide range of potential applications, including assisting patients with walking pathologies, acting as tools for rehabilitation, and enhancing the capabilities of healthy humans. However, applying these devices effectively in a real-world setting can be challenging, as the optimal design features and control commands for an exoskeleton are highly dependent on the current user, task and environment. Consequently, robust metrics and methods for quantifying exoskeleton performance are required. This work presents an analysis of walking data collected for healthy subjects walking with an active pelvis exoskeleton over three assistance scenarios and five walking contexts. Spatial and temporal, kinematic, kinetic and other novel dynamic gait metrics were compared to identify which metrics exhibit desirable invariance properties, and so are good candidates for use as a stability metric over varying walking conditions. Additionally, using a model-based approach, the average metabolic power consumption was calculated for a subset of muscles crossing the hip, knee and ankle joints, and used to analyse how the energy-reducing properties of an exoskeleton are affected by changes in walking context. The results demonstrated that medio-lateral centre of pressure displacement and medio-lateral margin of stability exhibit strong invariance to changes in walking conditions. This suggests that these dynamic gait metrics are optimised in human gait and are potentially suitable metrics for optimising in an exoskeleton control paradigm. The effectiveness of the exoskeleton at reducing human energy expenditure was observed to increase when walking on an incline, where muscles aiding in hip flexion were assisted, but decrease when walking at a slow speed. These results underline the need for adaptive control algorithms for exoskeletons if they are to be used in varied environments.

Comparison of sit-to-stand and static standing balance ability between patients with total knee arthroplasty and elderly healthy subjects

Identifying the functional status of patients after total knee arthroplasty is important. This study aimed to examine the differences in sit-to-stand and static standing ability balance between patients who underwent total knee arthroplasty and healthy participants. Twenty patients (mean age 70.05 years) who underwent total knee arthroplasty and 20 healthy participants (mean age 69.20 years) participated in this study. To assess the participants' sit-to-stand, the Good Balance System (Metitur Ltd, Finland) was used to measure each participant's mediolateral center of pressure (COP) displacement and time required to complete the sit-to-stand movement. To assess the participants' static standing balance, the Good Balance System was used to measure each patient's mediolateral COP displacement, anteroposterior COP displacement, and velocity moment when standing with eyes open and with eyes closed. A significant difference was found in the mediolateral COP displacement and the time required to complete the sit-to-stand movement in the two groups (P< 0.05). A significant difference was also found in the mediolateral and anteroposterior COP displacement and the velocity moment when standing with eyes open and with eyes closed in the two groups (P< 0.05). Patients who had total knee arthroplasty showed decreased sit-to-stand and static standing balance ability compared with the control group in the initial period after surgery.

Trunk rotation alters postural sway but not gait in female children and early adolescents: Results from a school-based screening for scoliosis

ObjectiveThe purpose of this study was to assess the influence of trunk rotation (TR) on postural sway and spatial-temporal parameters of gait in children and early adolescents screened at school for the presence of scoliosis. MethodsTwo hundred and fifty-five individuals aged 9–14 (141 boys, 114 girls) underwent trunk rotation (TR) assessment by means of angle of trunk rotation (ATR) measurements performed with Bunnell’s scoliometer. Participants with ATR ≥ 5° formed the TR group whose data were compared with those of a control group (CON) composed of individuals with ATR < 5° matched for age and anthropometric features. Postural sway was calculated on the basis of center of pressure (COP) time series acquired using a pressure plate. Spatial-temporal parameters of gait were derived from trunk accelerations collected by a single inertial sensor located in the low-back region. ResultsSway area, sway path, COP velocities in medio-lateral (ML) and antero-posterior (AP) directions and COP displacements in ML direction were found significantly higher in girls with TR, while no differences between the TR and CON groups were detected in boys. Both boys and girls with TR exhibited gait patterns similar to those of their CON schoolmates. ConclusionsThese findings suggest that even mild levels of TR may influence balance of female children and early adolescents screened for scoliosis, and thus early interventions including selective and task-oriented exercises appear advisable. In contrast, TR does not appear to influence gait, but further investigations are required to clarify whether different ATR cut-offs may reveal alterations of spatial-temporal parameters.

Effectiveness of Wii-based rehabilitation in stroke: A randomized controlled study.

To investigate the efficacy of Nintendo Wii Fit®-based balance rehabilitation as an adjunc-tive therapy to conventional rehabilitation in stroke patients. During the study period, 70 stroke patients were evaluated. Of these, 23 who met the study criteria were randomly assigned to either the experimental group (n = 12) or the control group (n = 11) by block randomization. Primary outcome measures were Berg Balance Scale, Functional Reach Test, Postural Assessment Scale for Stroke Patients, Timed Up and Go Test and Static Balance Index. Secondary outcome measures were postural sway, as assessed with Emed-X, Functional Independence Measure Transfer and Ambulation Scores. An evaluator who was blinded to the groups made assessments immediately before (baseline), immediately after (post-treatment), and 4 weeks after completion of the study (follow-up). Group-time interaction was significant in the Berg Balance Scale, Functional Reach Test, anteroposterior and mediolateral centre of pressure displacement with eyes open, anteroposterior centre of pressure displacement with eyes closed, centre of pressure displacement during weight shifting to affected side, to unaffected side and total centre of pressure displacement during weight shifting. Demonstrating significant group-time interaction in those parameters suggests that, while both groups exhibited significant improvement, the experimental group showed greater improvement than the control group. Virtual reality exercises with the Nintendo Wii system could represent a useful adjunctive therapy to traditional treatment to improve static and dynamic balance in stroke patients.