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Background Individuals with autism spectrum disorder (ASD) show a reduced ability to maintain postural stability, though motor control mechanisms contributing to these issues and the extent to which they are associated with other gross motor activities (e.g., stepping) are not yet known. Methods Seventeen individuals with ASD and 20 typically developing (TD) controls (ages 6–19 years) completed three tests of postural control during standing. During the neutral stance, individuals stood with their feet shoulder width apart. During the Romberg one stance, they stood with feet close together. During the circular sway, participants stood with feet shoulder width apart and swayed in a circular motion. The standard deviation (SD) of their center of pressure (COP) in the mediolateral (ML) and anteroposterior (AP) directions and the COP trajectory length were examined for each stance. We also assessed mutual information (MI), or the shared dependencies between COP in the ML and AP directions. Participants also completed a stepping task in which they stepped forward from one force platform to an adjacent platform. The amplitude and duration of anticipatory postural adjustments (APAs) were examined, as were the maximum lateral sway, duration, and velocity of COP adjustments following the initial step. We examined stepping variables using separate one-way ANCOVAs with height as a covariate. The relationships between postural control and stepping measures and ASD symptom severity were assessed using Spearman correlations with scores on the Autism Diagnostic Observation Schedule–Second Edition (ADOS-2) and the Autism Diagnostic Interview-Revised (ADI-R). Results Individuals with ASD showed increased COP trajectory length across stance conditions (p = 0.05) and reduced MI during circular sway relative to TD controls (p = 0.02). During stepping, groups did not differ on APA amplitude (p = 0.97) or duration (p = 0.41), but during their initial step, individuals with ASD showed reduced ML sway (p = 0.06), reduced body transfer duration (p p = 0.02) compared to controls. Greater neutral stance COPML variability (r = 0.55, p = 0.02) and decreased lateral sway (r = − 0.55, p = 0.02) when stepping were associated with more severe restricted and repetitive behaviors in participants with ASD. Conclusions We found that individuals with ASD showed reduced MI during circular sway suggesting a reduced ability to effectively coordinate joint movements during dynamic postural adjustments. Additionally, individuals with ASD showed reduced lateral sway when stepping indicating that motor rigidity may interfere with balance and gait. Postural control and stepping deficits were related to repetitive behaviors in individuals with ASD indicating that motor rigidity and key clinical issues in ASD may represent overlapping pathological processes.

Accidental falls are a major health concern among older adults. Currently, fall prevention programs employ clinical assessment scores for identifying elderly fallers based on cut-off values. Biomechanical parameters provide crucial information differentiating pathological gait and posture and can be used to classify elderly fallers and non-fallers. Pattern recognition models based on biomechanical parameters may provide greater insight for such classification. The purpose of this study was to compare the classification accuracy of different pattern recognition models for identifying elderly fallers using biomechanical parameters measured during balance and gait tasks. Pattern recognition models were also developed using clinical assessment scores and compared to the models based on biomechanical parameters for accurately identifying elderly fallers. Participants included 58 non-fallers (age = 72.3 ± 5.7) and 41 fallers (age = 74.0 ± 12.3) who performed balance and gait tasks on a walkway with embedded force plates and pressure mats. The parameters included 2D ground reaction force (GRF), center of pressure (COP), and the plantar pressure (PP). Using this data as input, different classification algorithms were used to build models. Maximum accuracy of 86.02% for classifying faller/non-faller categories was obtained using a classifier based on biomechanical parameters from combined gait and balance tasks. The GRF parameters ranked higher than COP and PP parameters based on F-score ranking suggesting predictor importance of GRF parameters. The classification performance was further improved by adding GRF parameters to the more commonly used COP parameters. However, the classifiers based on clinical assessment scores resulted in a maximum accuracy of 92.93% suggesting that elderly fallers can be accurately classified using pattern recognition models based on clinical assessment scores.

When people walk on a treadmill, significant differences exist in postural control if compared to walking on the ground. In this paper, a method combining linear and nonlinear analysis is proposed to evaluate the walking postural control ability. In this method, the movements of the upper body and the feet are analyzed separately, because these parts have more capacity to reflect the characteristics of people’s gait. On this basis, the linear and nonlinear indicators of each part are analyzed, and the postural control ability is evaluated. The method is validated by three healthy subjects walking on both the treadmill and the ground. In treadmill walking case, the results show a smaller upper trunk acceleration (UTa) in the anterior-posterior (AP) direction. In the foot movement analysis, there are significant differences in the performance indexes related to the center of pressure (CoP) when people are walking on the treadmill and the ground. When walking on the treadmill, the velocity, acceleration, and jerk of the CoP in the AP direction are smaller than those in the ground walking case. Besides, when people walk on treadmills at uniform speeds, their feet accelerate is less in the vertical direction, and they have shorter stride length (SL) and longer stride time (ST). These results suggest that people have better postural control when walking on a treadmill. This method can be used as a means of assessing people’s behavior when walking on various situations by evaluating their control posture ability.

Introduction: Globally, 300 million adults have clinical obesity. Heightened adiposity and inadequate musculature secondary to obesity alter bipedal stance and gait, diminish musculoskeletal tissue quality, and compromise neuromuscular feedback; these physiological changes alter stability and increase injury risk from falls. Studies in the field focus on obese patients across a broad range of body mass indices (BMI >30 kg/m2) but without isolating the most morbidly obese subset (BMI ≥40 kg/m2). We investigated the impact of obesity in perturbing postural stability in morbidly obese subjects elected for bariatric intervention, harboring a higher-spectrum BMI. Subjects and Methods: Traditional force plate measurements and stabilograms are gold standards employed when measuring center of pressure (COP) and postural sway. To quantify the extent of postural instability in subjects with obesity before bariatric surgery, we assessed 17 obese subjects with an average BMI of 40 kg/m2 in contrast to 13 nonobese subjects with an average BMI of 30 kg/m2. COP and postural sway were measured from static and dynamic tasks. Involuntary movements were measured when patients performed static stances, with eyes either opened or closed. Two additional voluntary movements were measured when subjects performed dynamic, upper torso tasks with eyes opened. Results: Mean body weight was 85% (p < 0.001) greater in obese than nonobese subjects. Following static balance assessments, we observed greater sway displacement in the anteroposterior (AP) direction in obese subjects with eyes open (87%, p < 0.002) and eyes closed (76%, p = 0.04) versus nonobese subjects. Obese subjects also exhibited a higher COP velocity in static tests when subjects’ eyes were open (47%, p = 0.04). Dynamic tests demonstrated no differences between groups in sway displacement in either direction; however, COP velocity in the mediolateral (ML) direction was reduced (31%, p < 0.02) in obese subjects while voluntarily swaying in the AP direction, but increased in the same cohort when swaying in the ML direction (40%, p < 0.04). Discussion and Conclusion: Importantly, these data highlight obesity’s contribution towards increased postural instability. Obese subjects exhibited greater COP displacement at higher AP velocities versus nonobese subjects, suggesting that clinically obese individuals show greater instability than nonobese subjects. Identifying factors contributory to instability could encourage patient-specific physical therapies and presurgical measures to mitigate instability and monitor postsurgical balance improvements.

Purpose The role of core stability in running and its influence on injury risk in runners is not well understood. The purpose of this study was to investigate the effect of core stability (and core fatigue) on running mechanics. We hypothesized that decreasing core stability in novice runners would result in altered running mechanics previously associated with increased risk for common lower extremity running injuries. Methods Three-dimensional running kinematics and kinetics and seated postural sway on an unstable surface were collected on 25 healthy, novice runners before and after they performed a core stability knockdown protocol (CSKP), designed to temporarily reduce participants' core stability in a single testing session. Results Linear mixed models demonstrated that the CSKP resulted in an increased peak knee flexion moment (0.51%BW·ht increase, effect size = 0.49, P = 0.021) and a decreased vertical average loading rate (4.5 BW·s decrease, effect size = 0.44, P = 0.037) during running, but no significant changes in peak knee adduction moment, knee adduction impulse, hip adduction moment, hip adduction impulse, or peak vertical ground reaction force (all P > 0.05). Of 25 runners, 20 demonstrated a measurable decrement in their core stability as defined by their seated postural sway center of pressure excursion changing more than the standard error of measurement of 76 mm. Conclusions An experimentally induced decrement in core stability in novice runners caused an increased peak knee flexion moment during stance, which has previously been associated with increased patellofemoral contact pressure during running. Therefore, these results demonstrate that insufficient core stability in novice runners may be a risk factor for developing patellofemoral pain. Other results did not support a role of core stability in other common overuse running injuries in this population.

In this study, experiments are conducted for four types of falls and eight types of activities of daily living with an integrated sensor system that uses both an inertial measurement unit and a plantar-pressure measurement unit and the fall-detection performance is evaluated by analyzing the acquired data with the threshold method and the decision-tree method. In general, the decision-tree method shows better performance than the threshold method, and the fall-detection accuracy increases when the acceleration and center-of-pressure (COP) data are used together, rather than when each data point is used separately. The results show that the fall-detection algorithm that applies both acceleration and COP data to the decision-tree method has a fall-detection accuracy of 95% or higher and a sufficient lead time of 317 ms on average.

Holding an object has been found to reduce postural sway during quiet standing. However, people normally stand to accomplish suprapostural goals, such as fitting a key into a lock. Postural control should therefore be assessed by examining postural outcomes in the context of suprapostural task performance. This study assessed whether holding an object increased standing postural stability and improved the performance of a concurrent precision manual task. A total of 15 young adults performed a precision manual task with their dominant hand while holding or not holding an object in their nondominant hand. Postural stability was assessed using measures of postural sway and time to boundary. Suprapostural task performance was assessed as an error count. Holding did not influence postural sway or suprapostural task performance. Discrepancies among previous studies coupled with the present findings suggest that the effects of holding an object on standing posture are highly sensitive to the experimental context. The authors provide several explanations for their findings and discuss the limitations of previous suggestions that holding an object may have clinical relevance for balance-compromised populations.

Accurate and reliable detection of the onset of gait initiation is essential for the correct assessment of gait. Thus, this study was aimed at evaluation of the reliability and accuracy of 3 different center of pressure–based gait onset detection algorithms: A displacement baseline–based algorithm (method 1), a velocity baseline–based algorithm (method 2), and a velocity extrema–based algorithm (method 3). The center of pressure signal was obtained during 10 gait initiation trials from 16 healthy participants and 3 participants with Parkinson’s disease. Intrasession and absolute reliability of each algorithm was assessed using the intraclass correlation coefficient and the coefficient of variation of center of pressure displacement during the postural phase of gait initiation. The accuracy was evaluated using the time error of the detected onset by each algorithm relative to that of visual inspection. The authors’ results revealed that although all 3 algorithms had high to very high intrasession reliabilities in both healthy subjects and subjects with Parkinson’s disease, methods 2 and 3 showed significantly better absolute reliability than method 1 in healthy controls (P = .001). Furthermore, method 2 outperformed the other 2 algorithms in both healthy subjects and subjects with Parkinson’s disease with an overall accuracy of 0.80. Based on these results, the authors recommend using method 2 for accurate and reliable gait onset detection.

To date, the human balance assessment is mainly achieved by measuring the center of pressure (COP) trajectory of upright posture. However, COP-based metrics provide inconclusive results under certain circumstances, due to the lack of relevance with the body balance mechanism. This paper developed a novel framework to measure the variability in body sway based on the Poincare analysis to enhance the balance assessment. It provided nonlinear parameters SD1, SD2, and their ratio SD1/SD2 as quantitative indicators of the local and global balance regulation capacities. 136 healthy adults were categorized into young and elderly groups and received test on a force platform. COP signals were recorded for 30 s under eyes-opened and eyes-closed vision conditions. The results were analyzed using the two-way mixed-design analysis of variance and show that the technology is able to reveal the effect of age and vision on the balance control by SD1, SD2, and SD1/SD2. SD1 mainly responded to vision, and SD2 was more influenced by age. Due to the information about the subtle adjustment during quiet standing, these Poincare indexes surpassed the conventional COP measurements in demonstrating the balance control behavior. It can be concluded that the supposed method of estimating the local and global variabilities is a valuable approach for the balance assessment.

This paper reports the kinematic, kinetic and electromyographic (EMG) dataset of human locomotion during level walking at different velocities, toe- and heel-walking, stairs ascending and descending. A sample of 50 healthy subjects, with an age between 6 and 72 years, is included. For each task, both raw data and computed variables are reported including: the 3D coordinates of external markers, the joint angles of lower limb in the sagittal, transversal and horizontal anatomical planes, the ground reaction forces and torques, the center of pressure, the lower limb joint mechanical moments and power, the displacement of the whole body center of mass, and the surface EMG signals of the main lower limb muscles. The data reported in the present study, acquired from subjects with different ages, represents a valuable dataset useful for future studies on locomotor function in humans, particularly as normative reference to analyze pathological gait, to test the performance of simulation models of bipedal locomotion, and to develop control algorithms for bipedal robots or active lower limb exoskeletons for rehabilitation., Measurement(s)kinematic data • kinetic data • electromyography • locomotor behavior trait • motion analysis dataTechnology Type(s)stereophotogrammetry • dynamometric force platform • electromyography device • multifactorial motion analysisFactor Type(s)type of locomotor task • age • sex • gait speed • body height • body weightSample Characteristic - OrganismHomo sapiens Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.11112980

Background Hippotherapy is described as a rehabilitation method for postural control in children with cerebral palsy. Horse's movements can be manipulated during hippotherapy's sessions with horse walking on different surfaces and at different speeds. The purpose of this study was to assess if dynamic sitting postural control in children with cerebral palsy in hippotherapy is modified when surfaces (sand or asphalt) and horse's walking speed (slow or faster) are changed. Methods Sixteen children participated in this crossover study. Eight bilateral spastic cerebral palsy children, age range (6–12 years), with Gross Motor Function Classification System levels III to IV, practicing hippotherapy and eight children with typical development (reference group), matched for age and sex. All children were evaluated during riding a horse on sand and asphalt surfaces and at slow (self-selected) and faster (30%) horse's walking speed. Center of pressure parameters were determined by a portable pressure measurement system positioned on the saddle. Findings Mediolateral displacement amplitude of the center of pressure was larger when the horse was on sand. Mediolateral and anteroposterior displacements amplitude and velocities of the center of pressure increased at horse's faster walking speed. Interpretation Our study test empirical procedures used in clinical practice and with a population widely reached by hippotherapy. In order to increase the demand for sitting postural control in children with cerebral palsy during horse riding, faster horse speed or riding on sand should be used.

Objective Considering the importance of balance in performing daily tasks and sports activities, it is necessary to examine the balance of the body from different angles. The aim of this study was to compare the changes in Center of Pressure (COP) and Time to Stabilization (TTS) in students with and without hyperlordosis. Methods In this study, 30 female students of Tehran's middle school with a range of 14-15 years old who were selected by available sampling method were participated. Subjects' spinal curvature was evaluated by a flexible ruler. Which divided into two groups: 15 patients with hypereloidosis and 15 healthy subjects. To assess postural static stability in a static state, from open and closed eyes on the force plate (Ver 3.0.2 model from an Iranian scientist) was used. also to assess postural stability in the dynamic state, the landing stability test on the force plate device was used. Independent Sample T test statistics were used to analyze the data. Results The results of the statistical test showed that there was no significant difference in the parameters of the center of pressure (COP) in two- position with open and closed eyes between the two groups of healthy and hyperlordosis (p>0.05). But the time to stabilization (TTS) between the two healthy groups and hyperlordosis was statistically significant (p

Background: People with Parkinson's disease (PD) often have backward displacement of their center of pressure (COP) during quiet standing and reduced stability limits, as compared to healthy controls. These kinetic characteristics may induce postural instability in people with PD.Objective: To investigate the short-term effects on COP displacements during quiet standing and forward leaning brought about by the post-incline leaning after-effects in people with PD.Methods: Twenty participants with PD were randomly divided into two groups (tilting and control groups). The tilting group was required to stand upright quietly on a tilting board angled to raise the front part of the feet. The control group was asked to voluntarily lean their bodies forward as far as possible. The total time of the intervention was 60 seconds for each group. The COP displacements during quiet standing and forward leaning were recorded before and after the intervention.Results: In the tilting group, the COP significantly shifted forward after the intervention compared to that before the intervention during quiet standing as well as forward stability limits; this did not happen in the control group.Conclusions: The post-incline leaning after-effects may induce the short-term effects of forward shifting of COP during quiet standing and expand the forward stability limits in people with PD.

Center of pressure (COP) trajectories of human can maintain regulation of forward progression and stability of lateral sway during walking. The insole pressure system can only detect COP trajectories of each foot during single stance. In this study, we developed artificial neural network models that could present COP trajectories in an integrated coordinate system during a complete gait cycle using pressure information of the insole system. A feed forward artificial neural network (FFANN) and a long short-term memory (LSTM) model were developed. For FFANN, among 198 pressure sensors from Pedar-X insoles, proper input variables were selected using sequential forward selection to reduce input dimension. The LSTM model used all 198 signals as inputs because of its self-learning characteristic. As results of cross-validation, the FFANN model showed correlation coefficients of 0.98-0.99 and 0.93-0.95 in anterior/posterior and medial/lateral directions, respectively. For the LSTM model, correlation coefficients were similar to those of FFANN. However, the relative root mean square error (12.5%) of the FFANN model was higher than that (9.8%) of the LSTM model in medial/lateral direction (p = 0.03). This study can be used for quantitative evaluation of clinical diagnosis and rehabilitation status for patient with various diseases through further training using varied databases. Graphical abstract Architectures of neural networks developed in this study (a feed forward artificial neural network; b LSTM network).

Background Changes in the motor control of the spine were found in patients with chronic low back pain (CLBP). Sudden loading of the spine is supposed to be the cause of about 12% of lower back injuries. However, some aspects of this problem, such as alterations in the sensory-motor control of the spine, remain questionable. Objective To investigate the effects of familiarization with loading, weight and size of loading on neuromuscular responses during sudden upper limb loading in CLBP patients. Methods In this quasi-experimental study surface electromyography of the erector spinae (ES) and transverses abdominis/internal oblique (TrA/IO) and external oblique (EOA) muscles were recorded in 7 men and 13 women with CLBP and 20 asymptomatic subjects (10 men and 10 women) aged 18-45 years from the general community familiarization. Moreover, investigating control of the posture measurements of the center of pressure (COP) and vertical ground reaction force (GRF) or Fz were recorded using a force plate. Data were analyzed using paired t-test and independent t-test with the significance level of 0.05. Results Data analyses were performed using SPSS version 18. Some electromyography and force plate variables were significantly different for different conditions in each group and between the asymptomatic and low back pain groups (p⩽ 0.05). Conclusion Several motor control changes were observed in the CLBP patients. These patients showed decreased trunk muscle activity as well as too early and too delayed responses compared to asymptomatic subjects.

This study was completed to validate a virtual reality (VR) headset (HTC ViveTM, Taiwan) as a tool to measure postural sway using the position and orientation tracking capabilities built into the VR system. If validated, the headset could be a cost-effective tool for balance assessments. Unity was used to develop an optical flow environment for VR. Study participants were able to experience three different speeds of optical flow displayed through the HTC Vive headset. However, for this study, participants were shown a scene in the virtual environment that did not move, causing no optical flow for the participant. A force plate and VR headset recorded position measurements during each trial. The Pearson correlation coefficients between the headset and the force plate data measurements were calculated in MATLAB, along with the root-mean-squared and peak-to-peak values for each trial. Results show that correlations in the AP plane tended to be greater than 0.4 and correlation in the ML plane tended to be greater than 0.6. The VR headset may be used for postural control measurements in clinic. However, further development of software and testing protocols for balance assessments is needed.

Postural stability and balance during manual material handling and industrial tasks are fundamental to ergonomic assessment of workplace tasks. Previous research has determined that accurate prediction of a person’s balance maintenance strategy is one of the most important parameters affecting the accuracy of posture prediction algorithms. Digital human modeling has the potential to provide designers with accurate tools to represent human posture, but currently available software typically lacks empirically-derived models of center of pressure (CoP) excursion. This paper presents an overview of a study that systematically quantified CoP excursion behavior through a series of standing reach tasks for participants with a wide range of body size. CoP excursion was greatly affected by foot placement and target location. The overall goal of this research is to develop an empirical model of center of pressure (CoP) excursion that can be integrated into human figure modeling software to improve prediction of standing postures typically observed in industrial tasks.

Objective We investigated the effects of eye movement with PNF neck movement on trunk stability and standing position balance ability of chronic stroke patients. Methods A total of 30 patients were randomly divided into EMPN group and CON group. EMPN group was performed 60 min three times a week for 8 weeks in eye movement and PNF neck movement. CON group performed conservative treatment for 60min. The trunk stability was measured by the Trunk impairment scale (TIS) and the standing balance ability test was performed by Center of Pressure (COP), Limited of Stability (LOS), Berg Balance Scale (BBS) and Functional Reach Test (FRT). Results There was a significant difference (P Conclusions In this study, we confirmed oculogyration and neck movement by PNF have positive effects on the trunk stability and the standing position balance ability of chronic stroke patients.

Background. In modern orthopedics, the problem of unilateral shortening of the lower limbs in children is extremely important. In the process of child growth, there occurs progression of the shortened segment, which leads to anatomical asymmetry of the lower limbs and an increase in the imbalance of the limb load. Secondary deformities of the pelvis and spine aggravate the patients disability. The features of abnormal postural balance of the body depending on the etiology of the disease, such as congenital or acquired, as well as the degree of preservation of motor stereotypes in children with unilateral shortening of the lower limbs, are still understudied. Aim. The aims of this work are to study postural stability in children with unilateral shortening of the lower limbs and to assess the disorders of body balance depending on the etiology of the lesion. Materials and methods. The standard stabilometric values of 11 healthy children (average age, 11.9 0.73 years) were determined (group 1), as well as the statokinesiogram parameters in 22 patients with unilateral shortening of the lower limb. The second group included 11 children (average age, 11.9 1.05 years) with congenital shortening of the lower limb (average shortening, 4.8 0.8 cm). The third group also consisted of 11 children (average age, 12.2 0.78 years), but with acquired shortening of the lower limb (average shortening, 4.5 0.38 cm). Statistical research included correlation analysis. Results. A significant decrease in the stability of the vertical balance was observed in both groups of patients, which was demonstrated by pronounced deviations from the nominal values of stabilometric parameters, compared with healthy children: an increased center of pressure displacement, large values of the statokinesiogram area, and the length of the pressure displacement path. It was possible to determine the state of adaptive postural mechanisms for assessing the formation of the degree of adequacy of the motor strategy in patients with unilateral shortening of the lower limb, depending on the etiology of the lesion, owing to the method of stabilometry. Conclusion. An appropriate adaptive motor stereotype has been formed in patients with acquired shortening of the lower limb; in the new conditions, the system for ensuring postural balance is stabilized. There is a different strategy for maintaining posture stability characterized by a nonoptimal motor stereotype in patients with congenital shortening of the lower limb. The stabilometric assessment of the asymmetry of the lower limb load is a promising method for studying the formation of compensatory mechanisms for controlling the locomotion system, which is important when planning rehabilitation measures.

Background The aim of the current study was to assess movement strategies during a single leg balance in chronic ankle instability individuals with unstable postural control strategy identified by Nyquist and Bode analyses in conjunction with sample entropy. Methods Thirty-three participants with self-reported chronic ankle instability and 22 healthy controls performed single-leg eyes closed static balance trials. The sagittal and frontal plane kinematics in the lower extremity and trunk as well as center of pressure trajectories were recorded during three, 20-second trials. The Nyquist and Bode stability analyses, which classify center of pressure waveforms as stable based on the resulting gain and phase margins, were performed to identify the presence of postural control deficits. Sample entropy was implemented to analyze movement strategies during the task. Findings Based on the Nyquist and Bode stability analyses, we included 19 out of 33 chronic ankle instability participants with unstable postural control strategy and 16 out of 22 controls with stable postural control strategy in the final analyses. Chronic ankle instability participants demonstrated a significantly lower sample entropy value in sagittal and frontal plane trunk kinematics and sagittal plane hip kinematics compared to the controls. No between-group differences existed in other kinematic measures. Interpretation The lower sample entropy values in participants with chronic ankle instability indicates that those with postural control deficits may increase reliance on the trunk and hip joint contributions to the maintenance of postural control, reflecting changes in the sensorimotor constraints on movement patterns during the task.

Background Adaptation to split-belt treadmill walking differs between individual stroke survivors. Many discussions only address spatiotemporal parameters that are related to movement, and the changes in interlimb spatiotemporal parameters as a consequence of adaptation are poorly understood. Objectives To investigate symmetry of the center of pressure (CoP) position relative to the center of mass (CoM), and ascertain whether this can be used to identify differences in adaptation of interlimb spatiotemporal parameters among stroke survivors during split-belt walking. Methods Twenty-two chronic post-stroke patients and nine elderly controls walked in tied- then split-belt (2:1 ratio of fast:slow) conditions. Spatiotemporal parameters were compared within groups to assess symmetry of the CoM-CoP angle at foot contact. Results Asymmetry of the CoM-CoP angle was associated with asymmetry of spatiotemporal parameters. Re-establishment of symmetry of CoM-CoP angle was reflected in re-established symmetry of spatiotemporal parameters in post-stroke and control participants. Conclusions Post-stroke patients who re-establish symmetry of the COM-COP angle are able to adapt their walking for split-belt perturbation. This suggests that predictively symmetric foot placements on the fast and slow sides are necessary for adaptation in walking. Symmetrical foot placement is achieved by interlimb coordination and may contribute to dynamic stability.

International audience; Background: Core strengthening prepares the body in an integral, safe and efficient way, favoring balance and postural control; physical abilities constantly demanded in sports, especially in body contact modalities, such as Judo.Objective: This study investigated the effects of core strengthening on balance in university judo athletes.Methods: Eighteen athletes from the University of Southern Santa Catarina (UNISUL) were randomly allocated into two groups: experimental (n = 9) and control (n = 9). Experimental group athletes were submitted to a core strengthening protocol (30-min sessions, twice a week for 5 consecutive weeks). Evaluations consisted of Stabilometic (center of pressure behavior parameters: total area in mm2, laterolateral and anteroposterior width in mm) and baropodometric analysis [peak pressure: obtained during a 30-s acquisition period and expressed by foot area, i.e., (a) forefoot (metatarsal heads and toes); and (b) hindfoot (calcaneus region, distal third of the foot)]. Right/left foot ratios were calculated as relative percentages and used for the analysis. The analyzes were performed at baseline and after 5 weeks of core strengthening. The athletes were evaluated in two situations: eyes-open and eyes-closed.Results: Total right/left foot ratio pressure, right/left fore and hindfoot ratio pressure, as well as anteroposterior width measurements were statistically smaller in the experimental group.Conclusion: Although the results obtained showed that core strengthening presents certain benefits, these data alone are not enough to confirm its effects upon postural oscillation in university judo athletes.

Background A few clinical trials have examined the effect of treatment interventions on postural control in patients with chronic low back pain, all of which have exclusively evaluated postural stability using traditional linear measures of postural sway. However, postural control improvement cannot be determined by exclusively relying on linear measurements, because these parameters provide no information on underlying motor control mechanisms. Objective This study aimed to compare the effect of using lumbosacral orthoses (LSO) together with routine physical therapy, compared to routine physical therapy alone on postural control, using nonlinear analysis techniques. Methods Forty-four patients with low back pain were randomly allocated to the intervention and control groups. Both groups underwent 8 sessions of physical therapy twice weekly for 4 weeks. The intervention group received LSO in addition to routine physical therapy. Before and after the intervention, non-linear dynamical features of center of pressure fluctuations were assessed during quiet standing at 3 difficulty levels of postural tasks, including eyes open while standing on a rigid surface, eyes closed while standing on a rigid surface, and eyes closed while standing on a foam surface. Results The results of this study showed that a 4-week intervention consisting of LSO and routine physical therapy modalities did not affect the temporal structure of postural sways in patients with low back pain. Conclusion Treatment strategies, such as routine physical therapy modalities or LSO, which exclusively focus on the correction of peripheral mechanics, fail to affect the behavior of the postural control system.

Background: Stroke patients have leg muscle weakness and impaired balance resulting in compensatory changes. To restore balance in these patients, functional training using postural strategy is needed. Objective: To examine the effects of ankle and hip strategy training on the center of pressure (COP) movement and limits of stability (LOS) in standing posture in stroke patients. Design: The study was an assessor-blinded and randomized-controlled clinical trial. Methods: Thirty patients were randomly assigned to an ankle strategy training group and a ankle/ hip strategy training group. Patients in the ankle strategy training group underwent ankle strategy exercise for 30 min, and those in the ankle/ hip strategy training group underwent 15 min of ankle strategy exercise and 15 min of hip strategy exercise. Both groups underwent training thrice a week for four weeks. Forward, backward, paretic side, and non-paretic side COP movements and LOS were measured using BioRescue. Results: After the intervention, except for the backward area in the ankle strategy training group, the COP movement area and the LOS were significantly improved in both the groups. In addition, these improvements were significantly higher in ankle/ hip strategy training group than that in the ankle strategy training group. Conclusions: Ankle strategy training in addition to hip strategy training improves COP movement (forward-backward, paretic side area, and nonparetic side area) and LOS in stroke patients.

When engaging in manual or visual tasks while sitting, infants modify their postural sway based on concurrent task demands. It remains unclear whether these modulations are sensitive to differences in concurrent task demands (holding a toy vs. looking at a toy being held by someone else), and whether the properties of the support surface impact these adaptations. We investigated infants' ability to modify postural sway when holding a toy or visually attending to a toy someone else was holding while sitting on different support surfaces. Twenty-six independently sitting infants sat on solid and compliant surfaces placed on a force plate while looking at or holding a toy. Measures of postural sway were calculated from the center of pressure data. Visually attending to a toy was associated with less sway and lower sway velocity than when holding a toy. Surprisingly, surface compliance did not affect sway and there were no interaction effects. Whereas sway modulations may facilitate infants' performance on both manual and visual concurrent tasks, the visual task placed more constraints on the postural system leading to greater adaptations in postural sway. These findings provide insights into how infants are allocating attention and coordinating perceptual-motor information in developing sitting skills.

Background: Balance requires highly complex interactions involving muscle strength, joint flexibility, visual, vestibular, and proprioceptive senses.Objective: The purpose of this pilot study was to compare the effects of COP (center of pressure) movement tracking training conducted using the Biodex Balance System SD® in static and dynamic modes on balance ability in stroke patients.Methods: Twenty-six stroke patients were randomly assigned to a control group (COP movement tracking training in static mode ; stable; n = 13 or an experimental group (COP movement tracking training in dynamic mode; unstable; n = 13). Both groups underwent neurodevelopmental therapy followed by an additional 15 min of COP movement training three times a week for 6 consecutive weeks. The timed-up and go test, COP pathway velocity, COP pathway length, and limit of stability were measured before and after intervention.Results: The experimental group showed greater reductions in COP pathway length and COP pathway velocity than the control group (5%, F (1, 24) = 6.125, p = .021, η2 = .203; 5.4%, F (1, 24) = 6.661, p = .016, η2 = .217, respectively). No significant intergroup difference was observed for the timed-up and go test or limit of stability results.Conclusion: COP movement tracking training in dynamic mode was found to be a more effective intervention for improving the static balancing abilities of stroke patients than training in static mode.

Objective The purpose of this study was to correlate potential the stabilometric parameters of baropodometry with the superficial temperature of the legs of cancer patients during and after treatment. Methods This study included 30 volunteers of both sexes, divided into the following groups: chemotherapy-radiotherapy group (n = 15; age = 57.13 ± 16.74 years) and cancer group without current treatment (n = 15; age = 63.29 ± 7.34 years). They were assessed for superficial temperature of the legs using infrared thermography with anterior and posterior views. Assessment of postural balance was conducted using a baropodometer, in 2 conditions—participants’ open and closed eyes—to obtain the center of pressure (COP) of anteroposterior displacement, center of pressure of mediolateral displacement (COP-ML), and center of pressure of displacement area. Results When their eyes were open, the chemotherapy-radiotherapy group presented a high correlation between the displacement of the ML and the surface anterior temperature of both legs (right: r = 0.578; P = .030; left: r = 0.619; P = .018) and posterior region of the right leg (r = 0.571; P = .033), and they presented a high correlation between COP with anterior surface temperature of both legs (right: r = 0.585; P = .028; left: r = 0.540; P = .046). When patients’ eyes were closed, no correlation was found between the thermography and the stabilometric parameters evaluated. Conclusion During the chemotherapy-radiotherapy, cancer patients present ML and COP displacement that correlates with infrared thermography evaluation when their eyes are open.

The stability of flapping flight, which is a natural requirement for flying insects, is one of the major challenges for micro aerial vehicles. A fully coupled computational model is employed that c...

[Purpose] This pilot study aims to determine whether improvements in postural sway, particularly among older adults, can be augmented immediately after training participants to activate and isolate the transverse abdominis (TrA) muscle. [Participants and Methods] Fifty six participants (in three age groups) took part in a single session TrA training intervention. Aspects of postural sway, balance and muscle activation patterns were measured before and after training and compared. [Results] There was significant improvement across four of six postural sway variables for the combined sample of all age groups. Older adults improved more than younger and middle-age participants in two important postural sway variables. No marked differences were evident in static reach distance across all age groups. There were no differences between groups with regard to surface electromyography (sEMG) amplitudes despite the emergence of different activation patterns among age groups. [Conclusion] Immediate effects were induced in postural sway measures after the single session training intervention. By improving neuromuscular control of the TrA and maximizing the efficiency of related proximal core muscles center of pressure (COP) sway velocities decreased during single limb standing (SLS).

Objective A new protocol based on the use of a gaming balance board for children with cerebral palsy was tested. Design A total of 56 children with cerebral palsy were enrolled and randomly divided into two groups: experimental and control. The children in experimental group underwent 12 wks of rehabilitation using their foot to play personal computer games with the proposed balance board, whereas those in the control group played personal computer games with a computer mouse in the standing position. Balance control was assessed before and after the intervention using the Zebris FDM System for measuring the center of pressure. The Pediatric Balance Scale and 2-min walk test were used for evaluating functional balance. Results In the analysis of covariance, the proposed new balance board used for the personal computer games decreased the postural sway (sway path, F = 6.95, P = 0.011; sway area, F = 11.79, P = 0.001) and improved the performance of the functional balance tests. Conclusions This study demonstrated the possibility that this new gaming balance board can be used for balance control in children with cerebral palsy.

Gait and postural control deficiencies in Parkinson's disease (PD) involve several specific motor aspects. The aim of this study was to identify and compare the main changes in gait kinematics and postural control with dopaminergic loss in the striatum region. This is a cross-sectional study that included 42 individuals with PD at different motor stages, according to the Hoehn & Yahr scale (H&Y). Motor subsection of the Movement Disorder Society-Unified Parkinson Disease Rating Scale-part III (MDS-UPDRS III) was used to evaluate general motor aspects. Gait kinematics was assessed using a three-dimensional motion capture system. Postural control was assessed by stabilometry using force platforms. Dopamine depletion was verified through 99mTc-TRODAT-1 (SPECT-CT) examination. We included 12, 15 and 15 individuals classified as H&Y I, II and III, respectively. We identified worse values of dopamine transporter uptake, MDS-UPDRS III, gait parameters (velocity, step length and stride length) and center of pressure displacement as the disease progressed. Our results indicate that higher dopaminergic loss and gait and postural control deficits occur between the H&Y levels II and III.

Made available in DSpace on 2019-10-06T17:05:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-08-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Introduction: Postural instability during walking and tripping over obstacles are the main causes of falls in people with Parkinson's disease (PD). Preliminary limited evidence suggests that the length of the prospective follow-up period affects falls prediction in PD, with shorter periods leading to more accurate prediction. Thus, the primary aim of the present study was to test the performance of center of pressure (CoP) variables during obstacle crossing to predict fall risk in people with PD during subsequent periods of four, six, and 12 months. We also compared CoP variables during obstacle crossing between fallers and non-fallers. Methods: Forty-two individuals with PD, in mild to moderate stages, completed the baseline obstacle crossing assessment and reported falls for 12 months. Participants walked at their self-selected pace and were instructed to cross an obstacle (half knee height) positioned in the middle of an 8-m long pathway. A force platform was used to analyze CoP parameters of the stance phase of the trailing limb (most affected limb). The ability of each outcome measure to predict fall risk at four, six, and 12 months was assessed using receiver operating characteristic curve analyses. Results: Ten individuals (23.8%) were considered fallers at four months, twelve individuals (28.5%) at six months, and twenty-one individuals (50%) at 12 months. CoP amplitude and CoP velocity in the mediolateral direction significantly predicted fall risk at four, six, and 12 months. As judged by the area under the curve, mediolateral CoP velocity showed the best performance at four months, while mediolateral CoP amplitude showed the best performance at six months. Fallers presented greater values of mediolateral CoP velocity and amplitude than non-fallers. Conclusion: These findings suggest that mediolateral CoP velocity and amplitude during obstacle crossing might be useful to predict fall risk in people with PD. Therefore, larger studies are encouraged. São Paulo State University (Unesp) Institute of Biosciences São Paulo State University (Unesp) Institute of Biosciences FAPESP: 2010/07040-0 FAPESP: 2014/22308-0

Humans will naturally synchronize their posture to the motion of a visual surround, but it is unclear if this visuomotor entrainment can be attenuated with an increased sensitivity to somatosensory information. Sub-threshold vibratory noise applied to the Achilles tendons has proven to enhance ankle proprioception through the phenomenon of stochastic resonance. Our purpose was to compare visuomotor entrainment during walking and standing, and to understand how this entrainment might be attenuated by applying sub-threshold vibratory noise over the Achilles tendons. We induced visuomotor entrainment during standing and treadmill walking for ten subjects (24.5 ± 2.9 years) using a speed-matched virtual hallway with continuous mediolateral perturbations at three different frequencies. Vibrotactile motors over the Achilles tendons provided noise (0–400 Hz) with an amplitude set to 90% of each participant’s sensory threshold. Mediolateral sacrum, C7, and head motion was greatly amplified (4–8× on average) at the perturbation frequencies during walking, but was much less pronounced during standing. During walking, individuals with greater mediolateral head motion at the fastest perturbation frequency saw the greatest attenuation of that motion with applied noise. Similarly, during standing, individuals who exhibited greater postural sway (as measured by the center of pressure) also saw the greatest reductions in sway with sub-threshold noise applied in three of our summary metrics. Our results suggest that, at least for healthy young adults, sub-threshold vibratory noise over the Achilles tendons can slightly improve postural control during disruptive mediolateral visual perturbations, but the applied noise does not substantially attenuate visuomotor entrainment during walking or standing.

This paper presents the development, characterization and application of a 3D-printed instrumented insole with polymer optical fiber (POF) sensors for static and dynamic assessments of plantar pressure and ground reaction force (GRF). The proposed insole has 15 intensity variation-based sensors multiplexed in a single POF using a time-domain multiplexing technique based on side-coupling between the light sources and POF lateral sections. The proposed insole was validated in dynamic and static tests compared with a commercial force platform. Results show a high correlation between the proposed insole and the force platform on GRF measurements and in the assessment of bidirectional displacement of the center of pressure. The correlation coefficient between the proposed 3D-printed insole and the platform was higher than 0.87 for all subjects and tests. In addition, the ability of detecting gait events and estimating users’ body mass were evaluated with errors lower than 3.4% for tests with 20 subjects. The proposed insole presents additional advantages of low cost, high portability and high degree of customizability, since the insole can be easily fabricated with personalized sizes and optimized sensors positions, which is regarded as an important asset for human-in-the-loop design of wearable devices for clinical evaluation and remote health monitoring.

There are contrasting views on the role of vision in modifying postural organization (information-driven and postural facilitation) and limited direct tests of the underlying postural mechanisms. Here, we examined whether the distinction between the two views is appropriate given that both are interrelated parts of task constraints modulating postural coordination and control. The study investigated whether changes in the organization of the postural system are a function of the visual precision demands of a task and, in addition, whether such organization could be described as reflecting an intermittent controller. Sixteen participants were instructed to maintain quiet postural stance while fixating a point at different viewing distances (25, 50, 135, 220, 305 cm) or standing with eyes closed. The 25-cm condition showed the lowest standard deviation of the center of pressure (COP) and the highest correlation dimension (CD) in the anterior posterior direction. Analyses revealed that, contrary to the intermittent controller hypothesis, adaptations in the continuous COP and center of mass (COM) coupling characterized the observed changes in CD. The findings show that the natural act of looking to the same feature in the environment as a function of visual viewing distance can lead to quantitative and qualitative changes in the dynamics of posture. This is consistent with the view that postural facilitation and information availability are integrated in the perceptual-motor dynamics.

Purpose: To evaluate whether a hippotherapy protocol may influence balance and gait in patients with Down Syndrome (DS). Methods: Fifteen male patients affected by DS underwent a 6-month hippotherapy protocol. Stabilometric, baropodometric, and gait assessments were performed at baseline (T0) and at the end of the treatment (T1). Results: At baseline, DS patients showed a low bilateral hind foot pressure percentage at the baropodometric analysis, a high center of pressure area in the closed-eye condition, a high center of pressure sway in open- and closed-eyes recordings, a high medio-lateral and antero-posterior velocity oscillations in the closed eye condition, and a reduced step-length and velocity. After the 6-month, hippotherapy protocol, DS patients had a significant bilateral higher hindfoot pressure percentage. The stabilometric analysis revealed a lower center of pressure area in the closed-eye condition, and a significantly reduced center of pressure sway in open- and closed-eyes recordings. In addition, DS patients showed lower medio-lateral and antero-posterior velocity oscillations in the closed eye condition. Finally, hippotherapy significantly improved step length and velocity. Conclusions: This pilot study demonstrates that hippotherapy determines functional improvement in gait speed, width, bilateral symmetry, and balance in DS.

Background Exercises are usually prescribed in association with orthotic intervention for management of idiopathic scoliosis, however the role of these exercises on the efficacy of brace and/or balance is not clear yet. Objectives To investigate the role of exercise (the Blount and Moe protocol) on static balance and Cobb angle changes in adolescents with spinal deformities during weaning from brace. Methods Seventeen brace users were allocated into 3 groups (good, moderate, and weak), according to their exercise quality and quantity static balance was evaluated on 4 conditions (standing on a platform/foam; with/without brace) using a force platform. Center of pressure displacement parameters were compared among the 3 groups. The mean Cobb angles of scoliosis and kyphosis at the beginning of brace use and at the start of the weaning phase were compared in general and among the 3 analogous groups. Results No significant difference was found in the static balance parameters and also in Cobb angles among the 3 groups. However, scoliosis and kyphosis Cobb angles were improved significantly as a result of using the brace (p Conclusions The exercise quantity and quality in association with bracing, up to the weaning phase, has no effect on static balance and changes in scoliosis and kyphosis, but the curvature of scoliosis and kyphosis is reduced after wearing a brace.

CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior FAPERJ - Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro Background: Single- and dual-tasks are influenced by age-related impaired postural balance. Aim of this study was to analyze the Center of Pressure (CoP) oscillation during static balance in the presence or absence of cognitive task on older women. Methods: Thirty-one healthy older women were assessed in a stand quiet position with open/closed eyes (single-task, OE and CE) and with cognitive task (dual-task, DT) through Wii Balance Board. Sway area, total displacement and CoP oscillation (CO) based on the number of times that CoP traveled through anteroposterior and mediolateral directions. Friedman test was used to compare OE, CE and DT. Dual-task interference percentage was used to quantify the cognitive load on balance whereas Spearman correlation coefficient was used to assess the association of cognitive domains and CO. Results: The CO was significantly higher in DT than in single-tasks and participants were unable to maintain their limits of stability in mediolateral direction. The cost of DT interference was 30.5%, which is partially explained by the deviation of attention from postural control to spatial and temporal orientation. Conclusion: Our findings show that cognitive load during DT impairs balance in mediolateral direction, thus indicating the use of WBB to assess cognitive interference on postural control.

Background: In the military, insufficient postural stability is a risk factor for developing lower extremity injuries. Postural stability training programs are effective in preventing these injuries. However, an objective method for the measurement of postural stability in servicemen is lacking. The primary objective of this study was to assess the influence of the number of repetitions, different foot positions and real-time visual feedback on postural stability, as well as their effects on the intrasession reliability of postural stability measurements in servicemen. The secondary objective was to assess the concurrent validity of the measurements. Methods: Twenty healthy servicemen between 20 and 50 years of age and in active duty were eligible for this quantitative, cross-sectional study. The measurements took place on a force plate, measuring the mean velocity of the center of pressure. The participants were asked to stand as still as possible in three different foot positions (wide stance, small stance, and on one leg), five times each for 45 s each time, and the measurements were performed with and without real-time visual feedback. Results: We observed a significant main effect of foot position (P < 0.001), but not of visual feedback (P = 0.119) or repetition number (P = 0.915). Postural stability decreased in the more challenging foot positions. The ICC estimates varied from 0.809 (one repetition in wide stance) to 0.985 (five repetitions on one leg). The common variance (R 2) between different foot positions without feedback varied between 0.008 (wide stance) and 0.412. Conclusions: To yield reliable data, wide-stance measurements should be conducted three times, and small-stance measurements and measurements on one leg should be conducted two times. The scores of a measurement in a particular foot position cannot predict the scores of measurements in other foot positions.

Background Fatigability and postural control deficits are both serious concerns in a variety of chronic musculoskeletal conditions. Research has shown that muscle fatigue may adversely affect postural control. This is while the evidence on the relevance of fatigue to postural control has never been summarized nor critically appraised. Research question Is there sufficient and strong enough evidence to accept trunk muscle fatigue as a contributing factor to postural control alterations during upright standing posture?. Methods EMBASE, Scopus, ELSEVIER, PubMed, ProQuest, Google scholar and reference lists of the relevant articles were searched through April 2018. Studies having investigated the trunk muscle fatigue effect on postural control in asymptomatic individuals were included in the study. Only those studies having assessed postural control in terms of center of pressure driven variables were included. Results Twelve studies (218 asymptomatic participants) matched the inclusion criteria of this systematic review. Their results supported the hypothesis that fatigue has a significant effect on postural control in terms of the time domain variables. Sway velocity was consistently found to be affected by fatigue. The results were inconsistent in the frequency domain. The only study on the structural dynamics of center of pressure displacements also confirmed such a relationship. Significance The present review indicates that postural control is altered in asymptomatic individuals following trunk muscle fatigue. This may suggest that trunk muscle endurance training is crucial to address postural impairment in chronic spine musculoskeletal conditions.

Background Freezing of gait (FOG) during gait initiation in people with Parkinson’s disease (PD) may be related to a diminished ability to generate anticipatory postural adjustments (APAs). Externally applied perturbations that mimic the desired motion of the body during an APA have been demonstrated to shorten and amplify APAs; however, no portable device has been tested. In this study, a portable powered ankle-foot orthosis (PPAFO) testbed was utilized to investigate the effect of mechanical assistance, provided at the ankle joint, on the APAs during gait initiation. Research question Does mechanical assistance provided at the ankle joint improve APAs during gait initiation in people with PD and FOG? Methods Thirteen participants with PD and FOG initiated gait across five test conditions: two self-initiated (uncued) conditions in walking shoes [Baseline-Shoes], and the PPAFO in unpowered passive mode [Baseline-PPAFOPassive]; three “go” cued conditions that included an acoustic tone with the PPAFO in unpowered passive mode [Acoustic + PPAFOPassive], the mechanical assistance from the PPAFO [PPAFOActive], and the acoustic tone paired with mechanical assistance [Acoustic + PPAFOActive]. A warning-cue preceded the imperative “go” cue for all the cued trials. Peak amplitudes and timings of the vertical ground reaction forces (GRFs) and center of pressure (COP) shifts from onset to toe-off were compared across conditions. Results Mechanical assistance significantly increased the peak amplitudes of the GRFs and COP shifts, reduced APA variability, and decreased the time to toe-off relative to the passive conditions. Significance These findings demonstrate the potential utility of mechanical assistance at the ankle joint (with or without an acoustic cue) as a method to generate more consistent, shortened, and amplified APAs in people with PD and FOG.

Background and purpose The maintenance of postural control is influenced by the complexity of a given task. Tasks that require greater attention and cognitive involvement increase the risk of falls among older adults. The aim of the present study was to evaluate the adaptation of the postural control system to different levels of task complexity in physically inactive young and older women. Methods A cross-sectional study was conducted with adult women classified as physically inactive based on the results of the International Physical Activity Questionnaire. The participants were 27 young (20-30 years of age) and 27 older (60-80 years of age) women. Sway velocity of the center of pressure in the anterior-posterior and medial-lateral directions was calculated using a force plate under 6 conditions: standing directly on the force plate or on a foam placed over the force plate, eyes open or closed, and dual-task complexity with and without the foam. Results and discussion A 2-way analysis of variance revealed that sway velocity increased in both groups when the task conditions were altered. The older women exhibited significantly greater sway velocity compared with the young women on all tasks. However, the patterns of postural control adaptation to the different levels of complexity were similar among all participants. Conclusions In this study, the adaption of the postural control system to different levels of task complexity did not differ between physically inactive young and physically inactive older women. However, the physically inactive older women exhibited greater sway velocity compared with the young women.

Summary Taking the average of different trials is recommended for better balance assessment, but few studies have really proven this point under different balance conditions. Objective To assess the effects of averaging trials of five different balance tasks on postural control measures in older women. Methods A total of 90 older women (means: Age: 68 years; Weight: 67 kg; Height: 1.56 m; Body mass index, 27 kg/m2) participated in this study. The participants completed five balance tasks with three performance trials for each task on a force platform in random order. The participants completed a total of three 30-s trials of tasks with 30 s of rest between trials. Repeated measure ANOVA and coefficient of variation were computed to compare differences for one trial vs. averaging across two or three trials on center of pressure (COP) sway values. Results There were no significant differences (P > 0.05) in COP sway values when comparing one vs. the average of two or three trials for all balance tasks. However, the coefficient of variation was higher for three trials (10–40%) than two (6–37%) or one trial (3–23%) for COP parameters. Conclusions Based on reduction of variability, the present study recommends the averaging of a minimum of two trials for balance assessment in older women. The results of the current study have implications for balance assessment in older people in fall prevention programs.

The aim of this study was to investigate the relationship between postural regulation and tracking accuracy under static and moving visual target conditions in unipedal and bipedal standing postures. Postural time-to-contact stability boundaries decreased under more challenging visual target conditions for the unipedal posture, but this decrease was associated with lower visual tracking error. During bipedal support, there was independent control of the head and foot center of pressure, as higher frequencies at the head during the static visual task were associated with longer time-to-contact. These results demonstrate that decreased time-to-contact stability boundaries is a functional adaptation in postural tasks requiring visual control and provide evidence of the dependency of postural control on the nature of the suprapostural task.