Time and frequency analysis of the static balance in young adults with Down syndrome

The effect of dual-task training on postural and cognitive performances in adolescents with down syndrome

BACKGROUND

The dual task training (DTT) has been shown to improve postural and cognitive performances in many populations. Therefore, it seems of interest to explore the effect of such training modality in individuals with Down syndrome (DS) presenting both cognitive and postural deficits.

AIMS

This study explored the effect of a DTT compared to a single task training (STT) on postural and cognitive performances in adolescents with DS.

METHODS AND PROCEDURES

The center of pressure velocity (CoPVm) and the cognitive performance in the selective word recall test were recorded under single task (ST) and DT conditions before and after 8 weeks in the STT group (STTG), the DTTG and the control group (CG).

OUTCOMES AND RESULTS

Before training, CoPVm values increased and cognitive performances decreased (p < 0.001) during the DT compared to ST conditions in all groups. After training, CoPVm decreased (p < 0.001) in the DTTG and the STTG under the ST conditions. However, under DT conditions, these values decreased (p < 0.001) only in the DTTG. The cognitive performance increased (p < 0.001) only in the DTTG in both ST and DT conditions.

CONCLUSION

The DTT is strongly recommended to improve both postural and cognitive performances in individuals with DS notably in DT conditions.

The influence of cognitive load and vision variability on postural balance in adolescents with intellectual disabilities

Introduction

This study aimed to investigate the impact of cognitive load, particularly its escalation during the execution of the same test, under varying vision conditions, on postural balance among adolescents with intellectual disability (ID).

Methods

Twenty adolescents underwent balance assessments under different visual conditions (Open Eyes (OE), Closed Eyes (CE), Flash, Goggles, Visual Stimulation (VS)) and task settings (Single Task (ST), Dual Task (DT) without challenges, and DT with challenges). The cognitive test was assessed using Verbal Fluency (VF).

Results and discussion

Significant effects were found for Task (p < 0.001, ηp2 = 0.85), indicating that CoP values significantly increased (p < 0.05) with the introduction of the DT. Dual Task Cost (DTC) demonstrated significant effects for Vision (p = 0.008, ηp2 = 0.62), with values varying significantly (p < 0.05) among different vision conditions, especially in CE and Flash conditions. Visual Dependency Quotient (VDQ) analyses revealed significant effects of condition (p < 0.001, ηp2 = 0.84), with significant changes observed in CE/OE and Flash/OE conditions (p < 0.05). Significant effects were observed for Cognitive performance in the Challenge condition (p < 0.001, ηp2 = 0.86), with decreased performance with cognitive task challenges, particularly in Flash and Goggles conditions (p < 0.05). In conclusion, cognitive tasks, especially challenging ones, and visual variations significantly impact postural balance in adolescents with ID.

Effect of dance movement therapy on balance in adults with Down Syndrome. A pilot study

Systematic participation in dance therapy may improve balance and reduce risk of falls. The aim of this study was to assess the effect of dance therapy on balance and risk of falls in adults with Down syndrome. Study participants comprised 23 persons with Down syndrome aged 26- 49 years who underwent dance therapy. Before and after the therapy, all participants were measured on a BioSway balance platform using three tests: postural stability, limits of stability, and M-CTSIB fall risk. Mean result was lower following intervention (2.40 ± 1.81 vs. 1.65 ± 1.32; p = .006) in the postural stability test. The limits of stability test found a statistically significant difference (26.30 ± 8.99 vs. 37.90 ± 12.54; p < .001). The results of this study only partially supported the hypothesis that dance therapy improves balancing skills in adults with Down Syndrome.

Effects of Smartphone Activities on Postural Balance in Adolescents with Intellectual Disabilities

Considering the rising prevalence of smartphone usage among adolescents with intellectual disabilities and their frequent motor challenges, understanding its impact on their physical well-being is important. This study aims to investigate the impact of smartphone activities on postural balance in adolescents with intellectual disabilities. Two groups of adolescents participated in the study: an intellectual disability group (IDG) (n = 16) and atypical development group (TDG) (n = 12). Static postural balance, using a stabilometric platform on firm and foam surfaces, and dynamic balance, using the Timed Up-and-Go Test (TUGT), were performed under various conditions, such as playing a game, watching videos, video calls, and listening to music. The center of pressure (CoP) values significantly increased (p < 0.05) during all smartphone activities (except listening to music) compared to the control condition in both groups, with the IDG demonstrated a more pronounced increase (p < 0.05) during playing video games and video calls on the firm surface. TUGT scores significantly increased (p < 0.05) during smartphone activities, with greater changes observed in the IDG (p < 0.05), and significantly decreased (p < 0.01) during listening to music in both groups. Our study suggests that adolescents with intellectual disabilities need special tools and guidance to ensure their safety and well-being when using smartphones.

Trend Change Analysis as a New Tool to Complement the Evaluation of Human Body Balance in the Time and Frequency Domains

Trend change analysis is a tool that complements the assessment of human body stability and provides information on the number and frequency of postural corrections during an examination. The present research aims to determine the possibility of using this method of analysis to investigate postural stability during tests of standing with open eyes (OE) and closed eyes (CE). A total of 118 participants (67 females, 51males) aged 23 (SD 1.3) were assessed. Tests involved standing on a stabilographic platform for 50 s. Trend change analysis was used to evaluate displacement values of the center of pressure (COP). Values for the COP courses as well as values associated with trend change analysis, such as: TCI, MACD_t and MACD_V were determined. Histograms of distribution were plotted for TCI values. The present study provides information on alterations of the strategy used for maintaining balance, which are associated with the number of postural corrections and COP displacement between corrections for measurements taken during the standing test with CE in relation to OE measurements. The strategy demonstrated an ability to detect a smaller number of quick corrections, an increased number of corrections of longer duration, and the elongation of displacement between subsequent postural corrections. Slight standard deviations in TCI and MACD_t values calculated during trend change analysis, for both the OE and CE conditions, made it possible to classify these values as indexes of postural stability with significant sensitivity to slight changes.

Cognitive-motor interference during standing stance across different postural and cognitive tasks in individuals with Down syndrome

BACKGROUND

Individuals with Down syndrome (DS) presented both cognitive and motor impairments that could influence each other. Therefore, exploring cognitive-motor interference during standing stance is relevant in this population.

AIMS

This study explored the dual task (DT) effects on postural balance during diverse cognitive tasks and sensory manipulations in individuals with DS, compared to those with typical development (TD).

METHODS AND PROCEDURES

Fifteen adolescents with DS (age = 14.26 ± 1.27 years; height = 1.50 ± 0.02; weight = 46.46 ± 4.03 kg; BMI =20.54 ± 1.51 kg/m²) and thirteen with TD (age = 14.07 ± 1.11 years; height = 1.50 ± 0.05; weight = 44.92 ± 4.15 kg; BMI =19.77 ± 0.94 kg/m²) participated in this study. Postural and cognitive performances for the selective span task (SST) and the verbal fluency (VF) were recorded during single task (ST) and DT conditions. Postural conditions were: firm eyes open (firm-EO), firm eyes closed (firm-EC) and foam-EO. Motor and cognitive DT costs (DTC) were calculated and analyzed across these different cognitive and postural conditions.

OUTCOMES AND RESULTS

In the DS group, postural performance was significantly (p < 0.001) altered during all DT conditions, compared to the ST situation. Moreover, the motor DTC was significantly (p < 0.001) higher while performing the VF task than the SST. However, in the control group, postural performance was significantly (p < 0.001) impaired only while performing the VF test in the DT-Firm EO condition. For both groups, cognitive performances were significantly (p < 0.05) altered in all DT conditions compared to the ST one.

CONCLUSION

Adolescents with DS are more prone to DT effects on postural balance than those with TD.

Effect of hippotherapy on balance, functional mobility, and functional independence in children with Down syndrome: randomized controlled trial

Impaired muscle strength, proprioceptive and vestibular deficits, and orthopedic dysfunction are common disorders associated with Down syndrome (DS). Hippotherapy uses the horses' multidimensional movement to improve posture, balance, and overall function, both motor and sensory. Research evidence supports hippotherapy as an effective, medically recognized intervention for the rehabilitation of gross motor skills. The aim of this study was to determine the effect of hippotherapy on balance, functional mobility, and functional independence in children with DS. Thirty-four children with DS were randomly assigned to the experimental (hippotherapy) and control groups after the initial assessment. Both groups received physiotherapy including balance exercises, and the experimental group also received hippotherapy as an integrative therapy. Pediatric Balance Scale (PBS), Timed Up and Go Test (TUG), and Functional Independence Measure for Children (WeeFIM) were used before and after the intervention. Baseline outcome measures (PBS, TUG, WeeFIM) were statistically similar between groups (p > 0.05). After the intervention, PBS and TUG scores improved in both groups (p < 0.05). On the other hand, WeeFIM scores improved just in the hippotherapy group (p < 0.05).   Conclusion: Therefore, providing hippotherapy as an integrative therapy to physiotherapy will be more effective in improving the functional independence of children with DS.    Trial registration: NCT05297149 (March 2022, retrospectively registered). What is Known: • Hippotherapy has an improvement effect on balance and functional independence in different diseases and age groups, but the evidence is limited in DS. • There is limited evidence about the effect of hippotherapy on functional mobility in different diseases and age groups, but there is no evidence in DS. What is New: • Hippotherapy is a safe and effective approach to support improvement in functional independence in children with DS.

Dual-task affects postural balance performance in children with intellectual disability

BACKGROUND

Dual-task designs have been used to study the degree of automatic and controlled processing involved in postural balance. The aim of the present study was to explore postural balance performance during dual-task condition in children with intellectual disability compared to those with typical development.

METHODS

Fifteen children with intellectual disability aged from 7 to 12 years old and fifteen age-matched children with typical development participated in this study. Participants were asked to maintain static balance on a force platform during a baseline condition (single task) and while performing the Picture Recognition Memory Test (dual-task condition).

RESULTS

The results showed that dual-task similarly affects postural performance of both typically developing children and those with intellectual disability (p < .001).

CONCLUSIONS

Children with intellectual disability and children with typical development have difficulties in maintaining their balance when carrying out a concurrent cognitive task. Intellectual disability did not lead to a more strongly compromised balance performance in dual-task situation.

The effect of a telehealth exercise intervention on balance in adults with Down syndrome

BACKGROUND

People with Down syndrome often present with balance deficits, which compromise safety during daily activity. While evidence shows that exercise can improve balance in the Down syndrome population, it is unclear if a telehealth method will elicit similar benefits. We aimed to examine the effects of a virtual exercise program on balance in adults with Down syndrome.

METHODS

Eighteen low-active participants with Down syndrome completed a 12-week telehealth exercise program based on the Mann Method. Balance testing took place before and after the intervention, which included: TUG, MCTSIB, FICSIT-4, and FRT. This study was registered as a clinical trial on ClinicalTrials.gov, identifier: NCT04647851.

RESULTS

Significant improvement was seen in the TUG (p = .043), FICSIT-4 (p = .019) and FRT (p = .019). All participants achieved maximum scores on the MCTSIB in pre- and post-testing.

CONCLUSIONS

Balance in low-active adults with Down syndrome significantly improved following the telehealth exercise program, which we attribute to the tailored exercises that address visual/vestibular deficits and hip muscle weakness.

Static postural balance between male athletes with intellectual disabilities and their sedentary peers: A comparative study

BACKGROUND

Previous reports showed that athletes without disabilities have better postural skills than their sedentary peers. This finding has not been elucidated in athletes with intellectual disabilities despite their decreased postural balance. This study aims to investigate static postural balance in track and field athletes with intellectual disabilities compared to their sedentary peers.

METHODS

Eighteen track and field athletes with intellectual disabilities (23.5 ± 4.52 years) and 18 sedentary peers (20.3 ± 3.4 years) participated in this study. A stabilometric platform was used to assess static postural balance in bipedal and unipedal stances with open (OE) and closed (CE) eyes.

RESULTS

In OE, the result showed significantly better static postural balance (CoP_Vm : p < .001; CoP_area : p < .001) in athletes compared to the sedentary ones in both stances. In CE, this difference was not observed in the unipedal stance.

CONCLUSION

Track and field experience may improve static postural balance in athletes with intellectual disabilities, mainly when visual input is available.

Multi-segmental postural control patterns in down syndrome

BACKGROUND

Patients with Down Syndrome (DS) exhibit less efficient and unstable standing postural control. The specificities of somatosensorial deficits might result in a different utilization of resources and in distinct whole-body kinematic patterns, to date still unexplored. In this paper we aim at addressing multi-segmental coordination patterns in people with DS while maintaining standing balance under different visual conditions (open and closed eyes).

METHODS

This cross-sectional observational cohort study involved two groups of 23 patients with DS and 12 healthy controls. A 30-s standing balance test allowed to extract (i) the length of the trajectory of the center-of-pressure sway and 95% confidence ellipse area from Ground Reaction forces, and (ii) Principal Movement (PM) components from full-body motion kinematics; the latter were obtained exploiting a Principal Component Analysis-based approach, also embracing a motor-control perspective through the evaluation of the number of modifications applied by the neuromuscular controller on segments' acceleration.

FINDINGS

Trajectory length was significantly higher in patients; 95% ellipse confidence area did not differ between groups/condition. Postural movement components differed in people with DS from healthy controls not only in the "observable", behavioural phenotype (PM3 and PM8), but also in the amount of activation of the associated control (PM1 to PM8, over-activated in DS) in all spatial directions.

INTERPRETATION

Results reinforced the prevalence of a medio-lateral hip strategy (instead of an ankle strategy) in maintaining postural stability. Most important, they revealed a less frequent activation of postural patterns in all spatial directions.

Conditional adaptive Bayesian spectral analysis of replicated multivariate time series

This article introduces a flexible nonparametric approach for analyzing the association between covariates and power spectra of multivariate time series observed across multiple subjects, which we refer to as multivariate conditional adaptive Bayesian power spectrum analysis (MultiCABS). The proposed procedure adaptively collects time series with similar covariate values into an unknown number of groups and nonparametrically estimates group-specific power spectra through penalized splines. A fully Bayesian framework is developed in which the number of groups and the covariate partition defining the groups are random and fit using Markov chain Monte Carlo techniques. MultiCABS offers accurate estimation and inference on power spectra of multivariate time series with both smooth and abrupt dynamics across covariate by averaging over the distribution of covariate partitions. Performance of the proposed method compared with existing methods is evaluated in simulation studies. The proposed methodology is used to analyze the association between fear of falling and power spectra of center-of-pressure trajectories of postural control while standing in people with Parkinson's disease.

Relationship between dynamic foot-ground contact area and balance impairments in adolescents with down syndrome

PURPOSE

Down Syndrome (DS) is characterized by intellectual disability, hypotonia, and joint laxity. Physical disability can be an additional problem and manifests as reduced lower limb muscle strength and impaired balance. The objectives of this study were to characterize DS dynamic foot-ground contact area and to study its relationship with balance impairment among adolescents with DS.

METHODS

Twenty-eight children and adolescents with DS and 28 non-DS adolescents/children were matched for age and sex. The Oxford Ankle Foot Questionnaire (parents' version) was used to measure disability related to ankle/foot problems in all subjects. A pressure-sensitive mat was used to assess the contact area and arch index. Also, a Biodex balance system was used for measuring postural stability.

RESULTS

There were significant differences between both groups in all domains of the Oxford Ankle Foot Questionnaire, overall contact area, and arch index (p < 0.05). Overall postural stability index was significantly decreased in subjects with DS (p < 0.05). There was a nonsignificant correlation between contact area and postural stability (p > 0.05).

CONCLUSION

Adolescents with DS exhibited larger mid-foot and forefoot contact areas with respect to non-DS matched children. Impairment of balance in adolescents with DS is a multifactorial problem not related to changes in the foot contact area.

Gait and postural control patterns and rehabilitation in Down syndrome: a systematic review

[Purpose] To describe (1) the current knowledge on gait and postural control in individuals with Down syndrome in terms of spatiotemporal, kinematics and kinetics, and (2) relevant rehabilitation strategies. [Methods] Randomized and non-randomized clinical trials published between January 1997 and October 2019 were selected by searching four scientific databases. We included studies on patients with Down syndrome involving gait analysis or postural control. A custom data-extraction and appraisal form was developed to collect the key features of each article. The PEDro Scale was used to evaluate the methodological quality of the studies. [Results] A total of 37 out of 146 cross-sectional and longitudinal studies were included in the review. The main abnormalities included: reduction of gait velocity and step length, poor static balance with increased anteroposterior and mediolateral oscillations and a larger step width. [Conclusion] A number of compensatory patterns during movement was observed, with a direct influence on improvements in stability and postural control throughout daily life. Intensive gait training at an early age appears to produce long-term improvements in this population. Future research should focus on the interaction between the motor and cognitive function, and on the functional effects due to the exposure to an enriched environment.

Empirical Frequency Band Analysis of Nonstationary Time Series

The time-varying power spectrum of a time series process is a bivariate function that quantifies the magnitude of oscillations at different frequencies and times. To obtain low-dimensional, parsimonious measures from this functional parameter, applied researchers consider collapsed measures of power within local bands that partition the frequency space. Frequency bands commonly used in the scientific literature were historically derived, but they are not guaranteed to be optimal or justified for adequately summarizing information from a given time series process under current study. There is a dearth of methods for empirically constructing statistically optimal bands for a given signal. The goal of this article is to provide a standardized, unifying approach for deriving and analyzing customized frequency bands. A consistent, frequency-domain, iterative cumulative sum based scanning procedure is formulated to identify frequency bands that best preserve nonstationary information. A formal hypothesis testing procedure is also developed to test which, if any, frequency bands remain stationary. The proposed method is used to analyze heart rate variability of a patient during sleep and uncovers a refined partition of frequency bands that best summarize the time-varying power spectrum.

Using a dual-task paradigm to investigate motor and cognitive performance in children with intellectual disability

BACKGROUND

The purpose of the current study was to evaluate the effects of dual-task (DT) constraints on walking performance in children with intellectual disability (ID).

METHODS

Fifteen children with intellectual disability and fifteen age-matched typically developed children were asked to walk at a preferred speed: along a path (baseline condition), while carrying a glass of water and while quoting animal names.

RESULTS

The present study findings showed that DTs affect walking performance of both typically developed children and those with intellectual disability. In children with intellectual disability, DT walking decrements were significantly higher when performing a concurrent motor task than cognitive one.

CONCLUSIONS

DT constraints with a secondary motor or cognitive tasks seemed challenging for children with intellectual disability suggesting that future treatments or assessments should consider using DT constraints to manipulate the difficulty of tasks.

Assessment of haemophilic arthropathy through balance analysis: a promising tool

The purpose of this study was to develop a tool able to distinguish between subjects who have haemophilic arthropathy in lower limbs and those who do not by analyzing the centre of pressure displacement. The second objective was to assess the possible different responses of haemophiliacs and healthy subjects by creating a classifier that could distinguish between both groups. Fifty-four haemophilic patients (28 with and 26 without arthropathy) and 23 healthy subjects took part voluntarily in the study. A force plate was used to measure postural stability. A total of 276 centre of pressure displacement parameters were calculated under different conditions: unipedal/bipedal balance with eyes open/closed. These parameters were used to design a Quadratic Discriminant Analysis classifier. The arthropathy versus non-arthropathy classifier had an overall accuracy of 97.5% when only 10 features were used in its design. Similarly, the haemophiliac versus non-haemophiliac classifier had an overall accuracy of 97.2% when only 7 features were used. In conclusion, an objective haemophilic arthropathy in lower limbs evaluation system was developed by analyzing centre of pressure displacement signals. The haemophiliac vs. non-haemophiliac classifier designed was also able to corroborate the existing differences in postural control between haemophilic patients (with and without arthropathy) and healthy subjects.

Stimulus Prediction and Postural Reaction: Phase-Specific Modulation of Soleus H-Reflexes Is Related to Changes in Joint Kinematics and Segmental Strategy in Perturbed Upright Stance

Anticipation determines the timing and efficiency of human motor performance. This study aimed to evaluate the effect of stimulus anticipation on proactive (prior to the event) and reactive (after the event) postural adjustments in response to perturbations. Postural set was manipulated by providing either (i) predictable, (ii) unpredictable, or (iii) cheated perturbations which require balance corrections to maintain postural stability. In 29 subjects, a protocol of anterior and posterior perturbations was applied for the conditions (i–iii). Center of pressure (COP) displacement, ankle, knee, and hip joint kinematics and electromyographic activity (EMG) of the soleus (SOL) and tibialis anterior (TA) muscles were recorded prior (PRE) and after posterior perturbations. SOL H-reflexes at the peak of the short-, medium- ,and long-latency responses (SLR, MLR, LLR) were assessed. For conditions (i to iii) EMG activity and COP differed prior to perturbation onset (p < 0.05). After perturbation, results demonstrated a progressively increased H-reflex amplitude in the MLR and LLR (p < 0.05), delayed muscle activities (p < 0.05), and shifted activation patterns, with muscles of the proximal segment being more involved in the compensatory postural response (p < 0.05). COP displacements and ankle, knee, and hip joint deflections progressively increased (p < 0.05). Neuromechanical coupling showed positive correlations for the anticipation-induced changes in EMG activity and H-reflex amplitude with that of COP displacement (p < 0.05). In conclusion, proactive and reactive postural responses indicated setting dependent modulations of segmental and phasic muscle activation. A shift to proximal muscle groups and facilitated late reflex responses compensating for cheated or unpredicted perturbations was found to recover a safe body equilibrium. In consideration of the phase-specific adaptation and its interrelationship to the kinematics, it suggested that changes in stimulus prediction challenged the central nervous system to appropriately counteract the higher postural challenges. The outcomes of this experiment are of functional relevance for experimental and training settings involving perturbation stimuli. These findings provide fundamental information of the mechanisms underlying postural adjustments in response to external perturbations.

Working Memory Task Influence in Postural Stability and Cognitive Function in Adolescents

This paper describes a study on postural stability and cognitive function according to the difficulty increment of a working memory task (WMT) and age group in adolescents. One hundred and twenty-three participants (13-16 years) performed single and dual tasks in a bipedal standing position while barefoot. Four trials were conducted, consisting of single and dual tasks in three progressively difficult WMT conditions (i.e., 3-, 5-, and 7-digit sequences). Friedman's analysis of variance and Kruskal-Wallis tests were conducted to test the effect of the WMT and age group, respectively. Both the WMT and age were found to affect performance (p < .01). As the cognitive requirements increased, the adolescents were not able to maintain their performance in both balance and cognition, while postural control and cognition were found to evolve with age.

Fundamental movement skills and balance of children with Down syndrome

BACKGROUND

Conclusive evidence supports the importance of fundamental movement skills (FMS) proficiency in promoting physical activity and countering obesity. In children with Down Syndrome (DS), FMS development is delayed, which has been suggested to be associated with balance deficits. This study therefore examined the relationship between FMS proficiency and balance ability in children with DS, with the aim of contributing evidence to programmes that address FMS delay.

METHODS

Participants consisted of 20 children with DS (7.1 ± 2.9 years old) and an age-matched control group of children with typical development (7.25 ± 2.5 years). In the first part of the study, FMS (i.e. locomotor and object control) proficiency of the children was tested using the Test of Gross Motor Development-2. Balance ability was assessed using a force platform to measure centre of pressure average velocity (AV; mm/sec), path length (mm), medio-lateral standard deviation (mm) and antero-posterior standard deviation (mm). In the second part of the study, children with DS participated in 5 weeks of FMS training. FMS proficiency and balance ability were tested post-training and compared to pre-training scores. Verbal and visuo-spatial short-term memory capacities were measured at pre-training to verify the role of working memory in skill learning.

RESULTS

FMS proficiency was associated with centre of pressure parameters in children with DS but not in children with typical development. After controlling for age, AV was found to predict significant variance in locomotor (R²  = 0.61, P < 0.001) and object control (R²  = 0.69, P < 0.001) scores. FMS proficiency and mastery improved after FMS training, as did AV, path length and antero-posterior standard deviation (all P < 0.05). Verbal and visuo-spatial short-term memory did not interact with the effects of training.

CONCLUSIONS

Children with DS who have better balance ability tend to have more proficient FMS. Skill-specific training improved not only FMS sub-skills but static balance stability as well. Working memory did not play a role in the changes caused by skills training. Future research should examine the causal relationship between balance and FMS.

The Effect of Visual Stimuli on Stability and Complexity of Postural Control

Visual input could benefit balance control or increase postural sway, and it is far from fully understanding the effect of visual stimuli on postural stability and its underlying mechanism. In this study, the effect of different visual inputs on stability and complexity of postural control was examined by analyzing the mean velocity (MV), SD, and fuzzy approximate entropy (fApEn) of the center of pressure (COP) signal during quiet upright standing. We designed five visual exposure conditions: eyes-closed, eyes-open (EO), and three virtual reality (VR) scenes (VR1–VR3). The VR scenes were a limited field view of an optokinetic drum rotating around yaw (VR1), pitch (VR2), and roll (VR3) axes, respectively. Sixteen healthy subjects were involved in the experiment, and their COP trajectories were assessed from the force plate data. MV, SD, and fApEn of the COP in anterior–posterior (AP), medial–lateral (ML) directions were calculated. Two-way analysis of variance with repeated measures was conducted to test the statistical significance. We found that all the three parameters obtained the lowest values in the EO condition, and highest in the VR3 condition. We also found that the active neuromuscular intervention, indicated by fApEn, in response to changing the visual exposure conditions were more adaptive in AP direction, and the stability, indicated by SD, in ML direction reflected the changes of visual scenes. MV was found to capture both instability and active neuromuscular control dynamics. It seemed that the three parameters provided compensatory information about the postural control in the immersive virtual environment.

The Feldenkrais Method improves functioning and body balance in people with intellectual disability in supported employment: A randomized clinical trial

Loss of functioning and age-related health problems tend to appear earlier in individuals with intellectual disability (ID) than in their non-disabled peers. The Feldenkrais method (FM) is a movement-based form of learning that enhances body balance and physical functioning. We carried out an intervention based on Awareness Through Movement, a form of the FM. Thirty-two middle-aged (48.94±6.01years old) adults with ID who were in supported employment were recruited and randomly assigned to the experimental group (EG) or control group (CG). The EG received 30 Awareness Through Movement classes while the CG did not receive any movement-based intervention. Physical functioning (body balance, gait speed and chair stands) was assessed with the Short Physical Performance Battery (SPPB) and balance by stabilometry. After 30 FM classes, individuals in the EG had significantly improved their chair stand test score (p<0.005) and SPPB total score (p<0.005), and reduced their sway area (p<0.05) in the stabilometric test. These results indicate that the FM could be a good tool for the prevention of loss of functioning and body balance in middle-aged individuals with ID.

Unilateral Fatigue Affects the Unipedal Postural Balance in Individuals With Intellectual Disability

This study aimed to explore the effect of local muscle fatigue on the unipedal stance in men with intellectual disability (ID). The Centre of pressure (CoP) excursions and the isometric maximal voluntary contraction (MVC) were measured before and after a fatiguing exercise. Higher baseline values of CoP excursions and lower MVC values were recorded in the ID group. After the fatiguing exercise, this group showed higher MVC decrease and higher percentage of increase of the mean CoP velocity. In conclusion, men with ID are more vulnerable to the disturbing effects of fatigue during the unipedal stance compared to men without ID.

Coupling between visual information and body sway in adults with Down syndrome

BACKGROUND

Prior studies suggest that infants with Down syndrome (DS) need more experience to acquire a similar relationship between visual information and body sway than infants without DS. However, it is unclear how adults with DS deal with visual information to control posture.

AIM

To examine the coupling between visual information and body sway in adults with DS.

METHODS

Twenty adults with DS (25.8±4.0years) and twenty age- and sex-matched controls (25.6±4.0years) stood upright inside a "moving room" in two experimental conditions: continuous (room oscillated continuously at 0.1, 0.2, and 0.5Hz) and discrete (room moved forward or backward for a brief moment). Tridimensional body sway and moving room displacement data were registered.

RESULTS

Individuals with DS coupled their body sway to the imposed visual stimulus, but showed higher position variability at frequencies other than the frequency of room movement (0.48cm) and lower coherence (0.80) than controls (0.40cm and 0.90, respectively).

CONCLUSIONS

Adults with DS were able to couple to the visual cue, but with differences in terms of the scaling of postural responses to spatial parameters of the visual stimulus.

The configuration of plantar pressure sensing cells for wearable measurement of COP coordinates

Background

Wearable measurement of center of pressure (COP) coordinates is the key of obtaining the measurement of natural gait. Plantar pressure insole is the right sensing unit for plantar pressure monitoring for long-term outdoor measurements and the control of walking assisting exoskeleton robot. It’s necessary to study the configuration of pressure sensing cells.

Methods

This study explored the sensing cell configuration for the plantar pressure insole. The data of plantar pressure of walking is collected for layout variants. The RMSE of COP coordinates estimations are used as the evaluation criteria.

Results

The RMSE of COP coordinates decreases from 8.00 to 3.20 mm as the amount of pressure sensing cells increases from 2 to 7. The size of pressure sensing cells contribute to reduce the RMSE of COP coordinates and 7 pressure sensing cells, with the size of 2.0–2.5 cm have the satisfying performance. Adding pressure sensing cell in the heel and hallux area increase the accuracy of estimating COP coordinates.

Conclusion

Comparison results indicate that the configuration of 7 pressure sensing cells has a satisfying measurement performance.

Differences in intermittent postural control between normal-weight and obese children

AIM

The main objective of this study was to determine differences in postural control between obese and non-obese children.

METHODS

The study design was cross-sectional, prospective, between-subjects. Postural control variables were obtained from a group of obese children and a normal-weight control group under two different postural conditions: bipedal standing position with eyes open and bipedal standing with eyes closed. Variables were obtained for each balance condition using time domain and sway-density plot analysis of the center of pressure signals acquired by means of a force plate.

RESULTS

Pairwise comparisons revealed significant differences between obese and normal-weight children in mean velocity in antero-posterior and medio-lateral directions, ellipse area and mean distance with both eyes open and eyes closed. Normal-weight subjects obtained lower values in all these variables than obese subjects. Furthermore, there were differences between both groups in mean peaks with eyes open and in mean time with eyes closed.

CONCLUSION

Alterations were detected in the intermittent postural control in obese children. According to the results obtained, active anticipatory control produces higher center of pressure displacement responses in obese children and the periods during which balance is maintained by passive control and reflex mechanisms are of shorter duration.

Changes in Balance Strategy and Neuromuscular Control during a Fatiguing Balance Task-A Study in Perturbed Unilateral Stance

Fatigue impairs sensorimotor performance, reduces spinal reflexes and affects the interaction of antagonistic muscles in complex motor tasks. Although there is literature dealing with the interference of fatigue and postural control, the interpretation is confounded by the variety of paradigms used to study it. This study aimed to evaluate the effects of postural fatigue on balance control and strategy, as well as on neuromuscular modulation, in response to postural perturbation (PERT) during a fatiguing balance task. A fatigue protocol consisting of continuous exposure to perturbations until exhaustion was executed in 24 subjects. Number of failed attempts, paths of center of pressure displacement (COP), ankle, knee, and hip joint kinematics, electromyographic activity of the soleus (SOL), tibialis anterior (TA), rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), and gluteus maximus muscles (GM) and spinal excitability of SOL at the peak of the short-latency responses (SLR) were recorded after posterior PERT. The co-contraction index (CCI) was calculated for TA_SOL, VL_BF and RF_GM. (1) The number of failed attempts significantly increased while COP amplitude and velocity, as well as angular excursion at the ankle, knee and hip joints, decreased with fatigue (P < 0.05). (2) Concomitantly, CCI of SOL_TA, VL_BF and RF_GM increased and spinal excitability in SOL declined. (3) Adaptations progressively augmented with progressing exhaustion and occurred in the distal prior to proximal segment. Distinctly deteriorated balance ability was accompanied by a modified neuromuscular control—the increase in co-contraction reflected by simultaneously activated antagonists is accompanied by smaller knee and hip joint excursions, indicating an elevated level of articular stiffness. These changes may be associated with an exaggerated postural rigidity and could have caused the delayed and reduced postural reactions that are reflected in the changes in COP displacement when compensating for sudden PERT. The reduction in spinal excitability may either be caused by fatigue itself or by an increase in reciprocal inhibition due to augmented TA activity.

The effect of a combined strength and proprioceptive training on muscle strength and postural balance in boys with intellectual disability: An exploratory study

The aim of our study was to investigate the effect of a combined strength and proprioception training (CSPT) program on muscle strength and postural balance in children with intellectual disability (ID). The maximum voluntary contraction (MVC) and postural parameters (CoPVm, CoPLX, CoPLY) of 20 children with ID were recorded before and after 8 weeks of a CSPT program. The participants were divided into two groups: an experimental group who attended a CSPT program and a control group who continued with daily activities. In the trained group, the MVC increased significantly (p<0.001) after the training period and the postural parameters decreased significantly in Double-Leg Stance (DLS) and One-Leg Stance (OLS) during the firm surface condition as well as in the DLS during the foam surface condition; in both eyes open (EO) and eyes closed (EC) conditions. A CSPT program improves postural balance in children with ID could be due to the enhancement in muscle strength and proprioceptive input integration.

Balance impairments and neuromuscular changes in breast cancer patients with chemotherapy-induced peripheral neuropathy

OBJECTIVE

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of cancer treatment. Resulting sensory and motor dysfunctions often lead to functional impairments like gait or balance disorders. As the underlying neuromuscular mechanisms are not fully understood, we compared balance performance of CIPN patients with healthy controls (CON) to specify differences responsible for postural instability.

METHODS

20 breast cancer patients with CIPN (PAT) and 16 matched CONs were monitored regarding centre of pressure displacement (COP) and electromyographic activity of M. soleus, gastrocnemius, tibialis anterior, rectus femoris and biceps femoris. We calculated antagonistic co-contraction indices (CCI) and elicited soleus H-reflexes to evaluate changes in the elicitability and sensitivity of spinal reflex circuitry.

RESULTS

PAT's COP displacement was greater than CON's (p=.013) and correlated significantly with the level of CCIs and self-reported CIPN symptoms. PAT revealed prolonged H-wave latency (p=.021), decreased H-reflex elicitability (p=.001), and increased H-reflex sensitivity from bi- to monopedal stance (p=.004).

CONCLUSIONS

We summarise that CIPN causes balance impairments and leads to changes in elicitability and sensitivity of spinal reflex circuitry associated with postural instability. We assume that increased simultaneous antagonistic muscle activation may be used as a safety strategy for joint stiffness to compensate for neuromuscular degradation.

SIGNIFICANCE

Sensorimotor training has the potential to influence neuromuscular mechanisms in order to improve balance performance. Therefore, this training modality should be evaluated as a possible treatment strategy for CIPN.

POSTURAL CONTROL MECHANISMS IN HEALTHY ADULTS IN SITTING AND STANDING POSITIONS

This study explored differences in the center of pressure in healthy people in a sitting and standing position and with eyes open and closed. With this purpose, 32 healthy participants (16 men, 16 women; M age=25.2 yr., SD=10.0, range=18-55) were measured with an extensiometric force plate. Using a two-way repeated-measures multivariate analysis of variance (MANOVA), the root mean square, velocity, range, and sway, in both visual conditions, had higher values in the standing task than in the sitting task. In the frequency domain, the low-frequency band had higher values during the standing task. For control mechanism variables, mean distance and time were greater when standing while mean peaks were greater when sitting. Thus, stability is worse in the standing position and more neuromuscular activity is required to maintain balance.

Load Dependency of Postural Control--Kinematic and Neuromuscular Changes in Response to over and under Load Conditions

Introduction

Load variation is associated with changes in joint torque and compensatory reflex activation and thus, has a considerable impact on balance control. Previous studies dealing with over (OL) and under loading (UL) used water buoyancy or additional weight with the side effects of increased friction and inertia, resulting in substantially modified test paradigms. The purpose of this study was to identify gravity-induced load dependency of postural control in comparable experimental conditions and to determine the underlying neuromuscular mechanisms.

Methods

Balance performance was recorded under normal loading (NL, 1g), UL (0.16g; 0.38g) and OL (1.8g) in monopedal stance. Center of pressure (COP) displacement and frequency distribution (low 0.15-0.5Hz (LF), medium 0.5-2Hz (MF), high 2-6Hz (HF)) as well as ankle, knee and hip joint kinematics were assessed. Soleus spinal excitability was determined by H/M-recruitment curves (H/M-ratios).

Results

Compared to NL, OL caused an increase in ankle joint excursion, COP HF domain and H/M-ratio. Concomitantly, hip joint excursion and COP LF decreased. Compared to NL, UL caused modulations in the opposite direction: UL decreased ankle joint excursions, COP HF and H/M-ratio. Collaterally, hip joint excursion and COP LF increased. COP was augmented both in UL and in OL compared to NL.

Conclusion

Subjects achieved postural stability in OL and UL with greater difficulty compared to NL. Reduced postural control was accompanied by modified balance strategies and compensatory reflex activation. With increasing load, a shift from hip to ankle strategy was observed. Accompanying, COP frequency distribution shifted from LF to HF and spinal excitability was enhanced. It is suggested that in OL, augmented ankle joint torques are compensated by quick reflex-induced postural reactions in distal muscles. Contrarily, UL is associated with diminished joint torques and thus, postural equilibrium may be controlled by the proximal segments to adjust the center of gravity above the base of support.

Can osteopathic manipulative treatment modify the posture in elderly people? - a single-case study

In this research, we have studied the consequences of three consecutive osteopathic manipulative sessions (OMS) on postural control by using a single-case research (SCR) design. The patient was a 77 years old woman complaining of altered balance and low-back pain. OMS were delivered by a single practitioner. The pain level was self-rated by using a visual Borg scale. The posture was monitored on a force platform. Postural parameters were deduced from the analysis of the centre of foot pressure (CoP) displacement. The statistical significance of the observed differences was established by using an SCR-related effect size indicator (i.e. Taunovlap). Our results indicate that OMS decrease the patient's pain, modify CoP mean position and decreased the length and velocity of the CoP displacement. Furthermore, modifications of the body oscillations were observed after OMS. This work indicates that OMS can improve body balance and that SCR allows the objective evaluation of the consequences of OMS.

Postural control during standing reach in children with Down syndrome

The purpose of the present study was to investigate the dynamic postural control of children with Down syndrome (DS). Specifically, we compared postural control and goal-directed reaching performance between children with DS and typically developing children during standing reach. Standing reach performance was analyzed in three main phases using the kinematic and kinetic data collected from a force plate and a motion capture system. Fourteen children with DS, age and gender matched with fourteen typically developing children, were recruited for this study. The results showed that the demand of the standing reach task affected both dynamic postural control and reaching performance in children with DS, especially in the condition of beyond arm's length reaching. More postural adjustment strategies were recruited when reaching distance was beyond arm's length. Children with DS tended to use inefficient and conservative strategies for postural stability and reaching. That is, children with DS perform standing reach with increased reaction and execution time and decreased amplitudes of center of pressure displacements. Standing reach resembled functional balance that is required in daily activities. It is suggested to be considered as a part of strength and balance training program with graded task difficulty.

Postural stability in young adults with Down syndrome in challenging conditions

To evaluate postural control and performance in subjects with Down syndrome (SwDS), we measured postural sway (COP) in quiet stance in four 20-second tests: with eyes open or closed and on hard or foam surface. Ten SwDS and eleven healthy subjects participated, aged 29.8 (4.8) and 28.4 (3.9), respectively. The time-series recorded with the sampling rate of 100 Hz were used to evaluate postural performance (COP amplitude and mean velocity) and strategies (COP frequency, fractal dimension and entropy). There were no intergroup differences in the amplitude except the stance on foam pad with eyes open when SwDS had larger sway. The COP velocity and frequency were larger in SwDS than controls in all trials on foam pad. During stances on the foam pad SwDS increased fractal dimension showing higher complexity of their equilibrium system, while controls decreased sample entropy exhibiting more conscious control of posture in comparison to the stances on hard support surface. This indicated that each group used entirely different adjustments of postural strategies to the somatosensory challenge. It is proposed that the inferior postural control of SwDS results mainly from insufficient experience in dealing with unpredictable postural stimuli and deficit in motor learning.

Effects of whole body vibration training on balance in adolescents with and without Down syndrome

The present study aimed to determine whether a whole body vibration training program (WBV) is able to improve static standing balance in adolescents with and without Down syndrome (DS). Thirty adolescents with DS aged 11-20 years (DSG) and 27 adolescent, age/sex matched, without DS (CG) joined the study. Participants of each group were divided into two comparable groups, those who performed WVB (in DSG: VDSG; in CG: VCG) and those who did not perform WVB (in DSG: nVDSG; in CG: nVCG). Static-standing-balance under four conditions (C1: open-eyes/fixed-foot-support; C2: closed-eyes/fixed-foot-support; C3: open-eyes/compliant-foot-support; C4: closed-eyes/compliant-foot-support) was examine, before and after a 20-week WBV training program. For balance study, Postural-Parameters (PPs), based on center of pressure (COP) oscillations (anterior/posterior and medial/lateral COP excursion and COP mean velocity), and PPs ratios among the four conditions were calculated. After WBV training, no significant differences were found in any parameter in the VCG and nVCG and neither in the nVDSG, but there was a decrease of mean values in the analyzed PPs under C4, with significant differences in medial/lateral COP excursion and COP mean velocity, and a significant decrease in the ratio C4/C1 of the mean velocity in VDSG. Therefore, WBV training had positive effects in the balance of DS adolescents although only under specific conditions, with vision and somatosensory input altered. The positive results of this study are encouraging and open a wide field of research, looking for the most efficient program for this population.

A subject-specific postural instability parameter

A mathematical modeling approach is applied for deriving subject-specific stabilometric parameters associated with center-of-pressure sway measurements for assessing balancing ability of subjects in quiet standing on a force platform. Based on the inverted pendulum model, a new combined stabilometric parameter including anthropometric characteristics (body height and mass) is obtained which represents a measure of postural instability. A physical meaning of the subject-specific parameter is related to the effective stiffness of the inverted pendulum model.

Sitting balance and limits of stability in persons with paraplegia

STUDY DESIGN

Cross-sectional, observational study of paraplegic and able-bodied persons.

OBJECTIVES

The aim of the study was to analyse the temporal and frequency domains of seated balance to better understand nervous system control in equilibrium in persons with spinal cord injury (SCI) and to explore their centre of pressure (CoP) limits before experiencing a fall.

SETTING

University of Valencia, Spain.

METHODS

Static and dynamic seated balance were assessed in 24 paraplegic persons divided into two groups: low paraplegia group (LP) and high paraplegia group (HP), and 24 healthy volunteers with an extensiometric force plate. Two types of tests were performed: a static test (ST), where data signal was analysed by temporal and frequency domains, and a stability limit test (SLT), where different stability limits were calculated.

RESULTS

The paraplegic group revealed lower static postural control in both domains in most of the parameters analysed compared with the control group (CG). Similar results were obtained with regard to the SLT, showing differences in the three parameters analysed between the CG and SCI groups.

CONCLUSION

Posturographic assessment in ST was useful to explore nervous system control in equilibrium in this population, presenting a decreased balance in paraplegic groups and an altered pattern in the sensorial and cerebellum bands compared with able-bodied individuals. Furthermore, SLT indicated less movement control of the CoP in paraplegic groups, which may influence the performance of their daily activities.

Static standing balance in adolescents with Down syndrome

AIM

To analyse static-standing-balance of adolescents with Down syndrome (DS).

METHODS

Thirty-two adolescents with DS aged 10-19 years (DSG); 33 adolescents, age/sex-matched, without DS (CG). Static-standing-balance under four conditions (C1: open-eyes/fixed-foot-support; C2: closed-eyes/fixed-foot-support; C3: open-eyes/compliant-foot-support; closed-eyes/compliant-foot-support) was examined by means of time and frequency Postural-Parameters (PPs). To evaluate the contribution of each sensory system influencing postural control ratios among the four conditions were calculated. Mean values of all PPs were higher in the DSG than in the CG. Mean values of time PPs were higher in both groups on compliant-foot-support (with open and closed eyes) than on fixed-foot-support. Ratios C2/C1 were significantly lower in DSG than in CG; ratios C3/C1 presented higher values in DSG than in CG, with significant differences in length path and RMS-velocity; there were no differences in ratios C4/C1.

CONCLUSIONS

In our group of DS adolescents the shift from visual to multimodal control of stance had occurred and they showed similar postural control patterns than non-DS. Even though, they presented worse static balance than their peers without DS and they had more problems with altered somasosensory input. An adequate rehabilitation program insisting on somatosensory input could be a useful measure to improve balance.

The effect of physical training on static balance in young people with intellectual disability

Intellectual disability affects all spheres of people's lives who suffer from it. It lowers the level of intellectual functioning, often stigmatizes, characteristically changing features, and decreases motor performance. Unfortunately, modern medicine cannot cure intellectual disability; however, there is a chance to improve the quality of life of people with mental retardation by means of physical exercises and by enhancing coordination, the quality of gait and efficiency in performing everyday activities. This paper deals with observations of static balance in 40 young females and males with mild Down syndrome, out of which 20 were subjected to a three-month sensorimotor training programme. The participants performed exercises with rehabilitation balls and air pillows twice a week, and the remaining persons constituted a control group. The balance platform test conducted at the beginning of the experiment revealed that the level of static one-legged balance was similar in both groups. A significant difference was noted in the length of the path of the general centre of gravity (COG) and the time frame in which the vertical projection of COG remained within the 13 mm radius circle, between the result of the test conducted under visual control and with the eyes closed, both in the group of the participants performing exercises and the ones who did not do them. After the training sessions the results of both tests improved in the group of the persons subjected to the training programme, however differences between the groups were not statistically significant, apart from the comparison of the time of keeping COG within the 13 mm radius circle at the beginning and at the end of the experiment by the participants who were physically active. Our results lead to a conclusion that exercises with the use of unstable surfaces improve deep sensibility in people with mild mental retardation.