Mean Sway Amplitude Research Articles

Diabetic older women without peripheral neuropathy amplify body sway but are capable of improving postural stability during a saccadic gaze task

BackgroundDiabetic older people tend to present deteriorated performance in balance and locomotion activities, even those without peripheral neuropathy. There is evidence that saccadic eye movements are used to reduce body sway in young and older healthy adults, but it has not been shown that diabetic older people preserve this visuomotor adaptation capacity. Research questionAre diabetic older women without peripheral neuropathy capable of improving postural stability during a saccadic gaze task? MethodsSeventeen type 2 diabetic older women (68.2 ± 10.7 years old) and seventeen healthy women, age-matched controls (66.0 ± 8.4 years old) voluntarily participated in the study. All participants were instructed to stand upright, barefoot, as stable as possible, for 30 s. Participants maintained their feet parallel to each other, at standard and narrow bases of support, while either fixating on a stationary target (fixation condition) or performing horizontal saccadic eye movements to follow a target (eccentricity of 11° of visual angle), which continuously disappeared and reappeared immediately on the opposite side (saccade 0.5 Hz and saccade 1.1 Hz conditions). ResultsResults indicated that the diabetic group clearly had deteriorated postural control, as shown by increased values of mean sway amplitude and mean sway velocity. However, diabetic and control groups were similarly capable of using saccadic eye movements to improve their postural stability, reducing their sway velocity compared to a gaze fixation condition. SignificanceDiabetes per se (without peripheral neuropathy) amplifies postural sway of older women as compared to their healthy age-matched controls. However, diabetic older women without peripheral neuropathy are capable of improving postural stability during a saccadic gaze task.

Visual Perturbation Suggests Increased Effort to Maintain Balance in Early Stages of Parkinson's to be an Effect of Age Rather Than Disease.

Postural instability marks a prevalent symptom of Parkinson’s disease (PD). It often manifests in increased body sway, which is commonly assessed by tracking the Center of Pressure (CoP). Yet, in terms of postural control, the body’s Center of Mass (CoM), and not CoP is what is regulated in a gravitational field. The aim of this study was to explore the effect of early- to mid-stage PD on these measures of postural control in response to unpredictable visual perturbations. We investigated three cohorts: (i) 18 patients with early to mid-stage PD [Hoehn & Yahr stage (1–3); 1.94 ± 0.70]; (ii) a group of 15 age-matched controls (ECT); and (iii) a group of 12 young healthy adults (YCT). Participants stood on a force plate to track their CoP, while the movement of their entire body was recorded with a video-based motion tracking system to monitor their CoM. A moving room paradigm was applied through a head-mounted virtual reality headset. The stimulus consisted of a virtual tunnel that stretched in the anterior-posterior direction which either remained static or moved back and forth in an unpredictable fashion.We found differences in mean sway amplitude (MSA) and mean velocities of CoP and CoM between the groups under both conditions, with higher MSA of CoP and CoM for PD and higher mean velocities of both variables for PD and ECT when compared with YCT. Visual perturbation increased mean CoP velocity in all groups but did not have effects on mean CoM velocity or MSA. While being significantly lower for the young adults, the net effect of visual perturbation on mean CoP velocity was similar between patients with PD and age-matched controls. There was no effect of the visual perturbation on mean CoM velocity for any of the groups.Our simultaneous assessment of CoP and CoM revealed that postural control is reflected differently in CoM and CoP. As the motion of CoM remained mostly unaffected, all groups successfully counteracted the perturbation and maintained their balance. Higher CoP velocity for PD and ECT revealed increased corrective motion needed to achieve this, which however was similar in both groups. Thus, our results suggest increased effort, expressed in CoP velocity, to be an effect of age rather than disease in earlier stages of PD.

Haptic Information Improvement on Postural Sway is Information-Dependent But Not Influenced by Cognitive Task

Young adults reduce their sway in both light touch (LT) and anchor systems (AS), however, the cognitive involvement in these tasks is unknown. This study investigated postural control in young adults standing upright using either LT or AS, concomitantly with a cognitive task (counting). Nine adults (26 ± 7.4 years) stood in the upright tandem stance with eyes closed, with/without LT, AS (force <2 N), and a cognitive task. The mean sway amplitude of the trunk, right wrist, and shoulder ellipse area, as well as the mean force during LT and AS were obtained. The cognitive task did not influence the magnitude of trunk sway or the mean force in the LT and AS conditions. The trunk sway magnitude was reduced in the AS and even further in LT. Wrist and shoulder variability was larger in the AS than in the LT. Based on these results, we conclude that enhanced sensory cues provided by LT and AS reduce trunk sway with little or no attentional demands.

Trunk and head displacements stabilized to perform both horizontal and vertical saccadic eye movements.

Vision is crucial for humans to interact with their surrounding environment, and postural sway is reduced to allow short eye movements. However, the extent of subtle changes in postural control for horizontal and vertical eye movements remains unclear. The goal of this study was to investigate the effects of vertical and horizontal eye movements on head and trunk control in young adults. Fifteen healthy adults (23.4 ± 4.7years) stood upright in three conditions for 60s: fixation, horizontal, and vertical guided eye movements. In fixation, participants had to fixate on a stationary target. In both the horizontal and vertical eye movements, the target was presented with a frequency of 0.5Hz and a visual angle of 11°. Eye displacement was monitored using a SMI eye tracker (ETG2.0) and trunk and head sway were monitored using infrared markers (Optotrak 3020, NDI). The mean sway amplitude was lower in both directions for eye movements and lowest in the vertical direction compared to the fixation condition. The sway area was also lower in vertical eye movement than in the fixation condition. We also found that the sway reduction was greater at head than at trunk level. The median frequency sway in the anterior-posterior direction was higher in both eye movements than in fixation. Based upon these results, we suggest that to perform short eye movements, postural sway is more strongly controlled at the head level than at the trunk and in vertical eye movements than in horizontal movements.

Performance of postural balance in children and adolescents living with and without HIV

Research questionThe present study aimed to compare the postural control of children and adolescents with and without Human Immunodeficiency Virus (HIV). MethodsA total of 32 children and adolescents (18 with HIV and 14 without) of both sexes, aged 6–18 years, were included in the present study. Participants in the HIV + group were infected through vertical transmission and received antiretroviral therapy. Participants maintained an erect, bipedal posture in the following conditions: with vision, without vision, and on a foam base. ResultsConcerning the evaluation of time variables, higher values ​​were observed in the HIV + group for mean anterior-posterior (AP) velocity, mean medial-lateral (ML) velocity, AP perimeter (p = 0.001), and ML perimeter (p = 0.001). Concerning the evaluation of conditions, a difference was observed in the mean AP mean sway amplitude (MSA) (p = 0.039), as the AP MSA was lower with vision than without vision or with foam. Concerning the evaluation of spectral domain variables, higher values ​​were observed in the HIV+ group for the predominant ML frequency (p = 0.04) and mean AP (p = 0.001) and ML frequencies (p = 0.001). Regarding the evaluation of conditions, a difference was found only in the predominant AP frequency (p = 0.001). Higher values ​​were found in the closed eye condition than in with foam (Δ = +103 %). ConclusionThe results of the present study indicated that children and adolescents living with HIV have poorer postural control performance than those without HIV.

Relations between postural sway and cognitive workload during various gaze tasks in healthy young and old people.

The purpose of this study was to determine whether postural control would differ under various gaze tasks while standing in a wide or narrow stance between healthy young and old people, and also investigate whether postural sway and cognitive workload are affected by dual-task balance. Ten young and 10 healthy old people participated in this study. Each participant stood upright under four gaze conditions (fixation, saccade, pursuit, vestibular-ocular reflex) and two stance conditions (wide and narrow stance) in a total of 16 trials. Postural sway was measured by the mean sway amplitude of the center of pressure in the medial-lateral and anteriorposterior directions. Cognitive workload was measured through pupil response as an index of cognitive activity (ICA) by using Eye tracking system and Eyeworks. The results showed that postural sway significantly reduced when performing saccadic eye movement in both groups but greater postural sway was evoked in vestibular-ocular reflex condition. In addition, although old people had a significant increase in ICA compared to the young, there were no significant differences among all the gaze conditions in old people. These results confirmed that saccadic eye movements are the most beneficial for reducing postural sway regardless of aging and also provide some insight that pupil response represents an indicator of cognitive workload during dual-task balance context. These findings suggest that eye movement exercises may be considered as an effective intervention to improve postural control so a fall prevention program applying eye movement should be extended to individuals who are at risk of falling.

Parkinson’s disease delays predictable visual cue processing without affecting complex and unpredictable visual cue processing in postural control

This study examined the influence of visual information of different complexities and predictability on the body sway of individuals with Parkinson's disease (PD) during upright stance. Twenty-one individuals at initial stages of PD (62.1 ± 7.2 years), under dopaminergic medication, and 21 controls (62.3 ± 7.1 years) stood inside a moving room, performing 10 trials of 60 s. In the first trial, the room remained motionless. Then, the room oscillated in an anterior-posterior direction. There were three blocks of three trials. In the first block, the room oscillated at 0.2 Hz (periodic simple condition); in the second block, periodic frequencies of 0.1, 0.3, and 0.5 Hz were combined (periodic complex condition); in the third block, non-periodic frequencies of 0.1, 0.3, and 0.5 Hz were combined (non-periodic complex condition). Participants were not informed about the room movement. The displacement of the room and trunk were registered using an OPTOTRAK system. Postural sway was examined using mean sway amplitude, and the relationship between visual information and body sway used coherence, gain, and phase. There was no group difference when the room remained motionless. Upon visual manipulation, the PD group displayed larger sway magnitude in the non-periodic complex condition. Individuals with PD also lagged behind the moving room (lower phase values) compared to controls, only in the periodic simple condition. In the remaining measures, there was no group difference. These results suggest that individuals with PD use complex and unpredictable visual information, similar to controls, during upright stance. However, PD might affect the predictable visual cues processing.

Wearing a head-mounted eye tracker may reduce body sway

This study investigated the effects of wearing a head-mounted eye tracker on upright balance during different visual tasks. Twenty five young adults stood upright on a force plate while performing the visual tasks of fixation, horizontal saccades, and eyes closed, during eighteen trials wearing or not a head-mounted eye tracker. While wearing the eye tracker, participants showed a reduction in mean sway amplitude and velocity of the CoP in the AP and ML directions and more regular CoP fluctuations, in the ML axis in all conditions. Higher mean sway amplitude and velocity of CoP were observed during eyes closed than fixation and saccades. Moreover, horizontal saccades reduced mean sway velocity of CoP compared to fixation. Therefore, wearing the eye tracker minimized the body sway of young adults; however, visual task-related effects on postural stability remained unchanged.

Force stability training decreased force variability of plantar flexor muscles without reducing postural sway in female older adults

BackgroundPrevious studies reported a relationship between postural sway and force variability of the plantar flexor muscles (PFM), such that less force variability related to lower postural sway; however, this association does not seem to exist in older adults. Research questionThis study investigated the effect of force stability training of the PFM on force variability (FV) of these muscles and postural sway in female older adults. MethodsThirty female older adults were divided into three groups: TG5 (n = 10), who trained at 5% of maximum voluntary isometric contraction (MVIC) of the PFM; TG10 (n = 10), who trained at 10 % of MVIC of the PFM; and CG (n = 10) who did not perform any specific training for the PFM. Postural sway was evaluated during upright bipodal posture. Postural sway and FV of the PFM were assessed before and after the training period. Participants trained once a week for four weeks. ResultsAfter the training period, the FV decreased significantly for both TG5 (pre = 3.26 ± 0.83; post = 2.53 ± 0.60 N) and TG10 (pre = 3.50 ± 0.72; post = 2.85 ± 0.86 N), but the mean sway amplitude increased for both TG5 (pre = 0.017 ± 0.03; post = 0.19 ± 0.04 cm) and TG10 (pre = 0.14 ± 0.04; post = 0.16 ± 0.04 cm). SignificanceThe force stability training decreased the FV of the PFM, but this decrease was insufficient to reduce postural sway in female older adults.

People in early stages of Parkinson's disease are able to intentionally reweight the use of visual information for postural control.

BackgroundParkinson’s disease (PD) leads to several changes in motor control, many of them related to informational or cognitive overload. The aim of this study was to investigate the influence of knowledge and intention on the postural control performance and on the coupling between visual information and body sway in people with and without PD standing upright.MethodsParticipants were 21 people with PD (62.1 ± 7.2 years), stages 1 and 2 (Hoehn & Yahr scale), under dopaminergic medication, and 21 people in the control group (62.3 ± 7.1 years). Participants stood upright inside a moving room, performing seven trials of 60 s. In the first trial, the room remained motionless. In the others, the room oscillated at 0.2 Hz in the anterior-posterior direction: in the first block of three trials, the participants were not informed about the visual manipulation; in the second block of three trials, participants were informed about the room movement and asked to resist the visual influence. An OPTOTRAK system recorded the moving room displacement and the participants’ sway. The variables mean sway amplitude (MSA), coherence and gain were calculated.ResultsWith no visual manipulation, no difference occurred between groups for MSA. Under visual manipulation conditions, people with PD presented higher MSA than control, and both groups reduced the sway magnitude in the resisting condition. Control group reduced sway magnitude by 6.1%, while PD group reduced by 11.5%. No difference was found between groups and between conditions for the coupling strength (coherence). For the coupling structure (gain), there was no group difference, but both groups showed reduced gain in the resisting condition. Control group reduced gain by 12.0%, while PD group reduced by 9.3%.ConclusionsPeople with PD, under visual manipulation, were more influenced than controls, but they presented the same coupling structure between visual information and body sway as controls. People in early stages of PD are able to intentionally alter the influence of visual information.

Applying precision triaxial accelerometer to monitor branch sway of an urban tree in a tropical cyclone

Trees are invaluable to urban landscape and environmental quality. However, tree failure can jeopardize life and property. Although the sway behavior of many coniferous species in temperate forest has been comprehensively evaluated, few studies have covered broadleaf tropical trees. This research aims at demonstrating the application of a new precision triaxial accelerometer to assess branch sway of an urban tree in tropical Hong Kong, testing the use of quantitative analysis to the large volume of generated sway and wind data, and identifying the factors influencing the branch sway behavior of the sampled tree. Following the tree selection criteria, four branches that are respectively healthy, crossed, wounded and hollow on a broadleaf deciduous Delonix regia (Flame of the Forest) were monitored by high-precision Tree Motion Sensors (TMS) during a tropical cyclone event. The results indicate significant inter-branch and axial difference in time-domain and frequency domain sway behavior. The average fundamental frequency of the branches ranged from 0.471 to 0.593 Hz. Mean sway amplitude (SAMEAN) correlated the best with wind speed fluctuations (maximum ρ = 0.801). Scientific instrumentation and data processing, such as the SAMEAN approach to monitor branch sway, can inform tree-risk management actions to abate possible failure. The approach undertaken in this study is an appropriate and effective means of monitoring tree sway and interpreting the associated data.

Intradialytic exercise and postural control in patients with chronic kidney disease undergoing hemodialysis

Abstract Introduction: Exercise promotes physiological improvements that reflect better quality of life and survival among chronic kidney disease patients. However, little is known about the effect of exercise on postural control of hemodialysis patients. Objective: To evaluate the effect of intradialytic aerobic exercise on postural balance in patients on hemodialysis. Methods: a pilot study with seven individuals was conducted at the Hemodialysis Center of Bauru State Hospital. The Berg Balance Scale evaluated balance and postural balance was evaluated by the force platform Advance Mechanical Technology Inc. (AMTI - AccuGait). Trunk mean sway amplitude in the anterior-posterior (AP) and medial-lateral (ML) directions and mean velocity in the AP and ML directions were assessed. Secondary outcomes about functional capacity and body composition (DEXA) were evaluated. The aerobic exercise was performed with a ergometric bicycle during the first two hours of hemodialysis session for 50-60 minutes (BORG &gt;12), three times a week for 12-weeks. Results: Four men and three women, 52.86 ± 11.08 years, participated in the study. There was no difference between pre and post-test of postural balance outcomes. Although the results were not statistically significant, except for the lean body mass and leg lean mass, the presented pilot study suggests improved functional balance and lower limb strength. Conclusion: The 12-weeks of aerobic exercise protocol during hemodialysis despite inducing gains in lean body mass and leg lean mass, was not able to promote improvements in postural control of chronic renal failure patients on hemodialysis.

A contribuição do sistema âncora em diferentes segmentos corporais para o controle da postura em idosos

RESUMO O sistema âncora é uma ferramenta não rígida que fornece informação háptica adicional, consistindo de dois cabos maleáveis com 125 g de massa repousando no solo, devendo-se segurar a outra extremidade com as mãos (âncora-mão). Considerando que o toque leve em diferentes partes do corpo reduz a oscilação corporal, é possível, da mesma forma, que o uso do sistema âncora em diferentes partes do corpo seja efetivo. Portanto, o objetivo deste estudo foi investigar o efeito do uso do sistema âncora em diferentes segmentos corporais sobre a oscilação corporal de idosos. Trinta idosos participaram do presente estudo. Eles ficaram na postura ereta com os pés na posição semi-tandem sobre uma plataforma de força para a obtenção do deslocamento do centro de pressão (CP). Cinco condições experimentais foram realizadas: sem âncora, âncora-mão, âncoras nas mãos presas com presilhas, âncoras nos antebraços presas com presilhas e âncoras nos ombros presas com presilhas. Os resultados mostraram uma redução da área da elipse ajustada ao deslocamento do CP e na amplitude média de oscilação na direção anteroposterior nas condições com as âncoras posicionadas nas mãos (âncora-mão e presilha) e antebraços em comparação à condição sem âncora. Assim, o uso do sistema âncora foi efetivo quando as âncoras foram posicionadas no antebraço da mesma forma que quando foram seguras pelas mãos. A melhora observada com o uso das âncoras parece não estar relacionada com a quantidade de receptores táteis no ponto de contato dos cabos das âncoras.

Impact Of Working Hours In Worker’S Postural Control.

Shift work, working hours, overtime, and insufficient rest time are factors that interfere with sensory-motor integration and consequently with postural control. PURPOSE: The purpose of this study was to verify the changes in postural control of workers undertaking different shift systems and working hours. METHODS: Thirty-two night workers were included, 12 bus drivers (42±8y) who worked eight-hours in a 5-consecutive-night system, with two days off, and 20 polysomnography technicians (35±7y) who worked in a 12x36h night-system, that is, 12 hours working and 36 hours off. All participants wore wrist actigraphs for four days. On the fourth day, before and after shift, they fulfilled the Karolinska Sleepiness Scale and were evaluated in a force platform for measures of postural control performance, standing as still as possible for 30 seconds with eyes-opened. Analyzes of Variance were used to compare the variables before and after shift, and statistical significance set at 5%. RESULTS: A significant and average increase of 2.15±1.59 points in the KSS was observed after-night shift for workers, as well as an increase of 0.15±0.03cm in mean sway amplitude. ROC curve analysis evidenced that an increase of at least 0.17cm in mean sway amplitude discriminates sleepy and non-sleepy individuals (scores greater than 7 in the KSS) with 72% sensitivity and 86% specificity. CONCLUSION: Our findings suggest that longer working hours may have a negative impact in postural control, independently of age, and with an additive effect of body mass index. Shift system (5x2 days or 12x36 hours) is more important in determining the level of impairment in postural control than is working hour’s duration per se and, therefore, future investigations should be aimed. Financial Support: CAPES, CNPQ, CEMSA, CEPE.

Is there a relationship between complaints of impaired balance and postural control disorder in community-dwelling elderly women? A cross-sectional study with the use of posturography.

Background:Risk of falls increases as age advances. Complaints of impaired balance are very common in the elderly age group. Objectives:The objective of this study was to investigate whether the subjective perception of impaired balance was associated with deficits in postural control (objective analysis) in elderly community-dwelling women. Method:Static posturography was used in two groups: elderly women with (WC group) and without (NC group) complaints of impaired balance. The area, mean sway amplitude and mean speed of the center of pressure (COP) in the anterior-posterior (AP) and medial-lateral (ML) directions were analyzed in three stances: single-leg stance, double-leg stance and tandem stance, with eyes open or closed on two different surfaces: stable (firm) and unstable (foam). A digital chronometer was activated to measure the time limit (Tlimit) in the single-leg stance. Kruskal-Wallis tests followed by Mann-Whitney tests, Friedman analyses followed by post hoc Wilcoxon tests and Bonferroni corrections, and Spearman statistical tests were used in the data analysis. Differences of p<0.05 were considered statistically significant. Results:The results of posturography variables revealed no differences between groups. The timed single-leg stance test revealed a shorter Tlimit in the left single-leg stance (p=0.01) in WC group compared to NC group. A negative correlation between posturography variables and Tlimit was detected. Conclusions:Posturography did not show any differences between the groups; however, the timed single-leg stance allowed the authors to observe differences in postural control performance between elderly women with and those without complaints of impaired balance.

Dyslexic children suffer from less informative visual cues to control posture.

The goal of this study was to investigate the effects of manipulation of the characteristics of visual stimulus on postural control in dyslexic children. A total of 18 dyslexic and 18 non-dyslexic children stood upright inside a moving room, as still as possible, and looked at a target at different conditions of distance between the participant and a moving room frontal wall (25-150 cm) and vision (full and central). The first trial was performed without vision (baseline). Then four trials were performed in which the room remained stationary and eight trials with the room moving, lasting 60s each. Mean sway amplitude, coherence, relative phase, and angular deviation were calculated. The results revealed that dyslexic children swayed with larger magnitude in both stationary and moving conditions. When the room remained stationary, all children showed larger body sway magnitude at 150 cm distance. Dyslexic children showed larger body sway magnitude in central compared to full vision condition. In the moving condition, body sway magnitude was similar between dyslexic and non-dyslexic children but the coupling between visual information and body sway was weaker in dyslexic children. Moreover, in the absence of peripheral visual cues, induced body sway in dyslexic children was temporally delayed regarding visual stimulus. Taken together, these results indicate that poor postural control performance in dyslexic children is related to how sensory information is acquired from the environment and used to produce postural responses. In conditions in which sensory cues are less informative, dyslexic children take longer to process sensory stimuli in order to obtain precise information, which leads to performance deterioration.

Uso da informação somatossensorial adicional no controle postural: efeito da dominância manual

Buscamos com o presente estudo investigar o efeito da dominância manual e da visão no uso da informação somatossensorial adicional fornecida pelo toque suave no controle postural. Quinze adultos jovens e destros permaneceram em pé sobre uma plataforma de força com a) olhos abertos ou fechados e b) braços ao lado do corpo ou o dedo indicador direito ou esquerdo tocando a barra fixa. A área do centro de pressão (CP), amplitude e velocidade médias do CP nas direções anteroposterior e médio-lateral foram avaliadas. Os resultados indicaram uma redução nas medidas nas condições de toque e aumento com os olhos fechados, exceto quando o toque foi realizado com dedo indicador direito. A força máxima foi maior para a mão direita, enquanto a sensibilidade cutânea e as forças aplicadas à barra foram similares entre os hemicorpos. Esses resultados sugerem um efeito da dominância manual e visão no uso da informação somatossensorial adicional no controle postural.

The reliability and validity of the sacral marker method when evaluating the balance of stroke patients using three dimensional motion analysis

Objective To study the reliability and validity of using sacral markers in evaluating the balance function in standing and walking of stroke patients with hemiplegia.Methods Twenty-one hemiplegic stroke patients were recruited and their baseline mean sway amplitude (MSA) and mean sway velocity (MSV) were measured using sacral markers and center of gravity analysis assuming a segmented body,the gold standard for such analysis.The data were analyzed using Bland-Altman plots to obtain the 95％ limits of agreement (LOA).Results ①Test-retest reliability:The 95％ LOA of the MSA in standing was (-4.42,5.14) on the X axis,(-6.04,4.52)on the Y axis,and (-1.75,1.31) on the Z axis.The MSV in standing was (-0.08,0.09) on the X axis,(-0.10,0.08) on the Y axis and (-0.03,0.02) on the Z axis.The 95％ LOA of the MSA in walking was (-185.74,105.53) on the X axis,(-22.57,2.76) on the Y axis and (4.43,2.76) on the Z axis.The MSV in walking was (-3.10,1.76) on the X axis,(-0.38,0.54) on the Y axis and (-0.07,0.02) on the Z axis.②Validity:The 95％ LOA of the MSA in standing was (-3.62,2.55) on the X axis,(-3.95,3.94) on the Y axis and (-7.35,19.43) on the Z axis.For the MSV in standing it was (-0.06,0.04) on the X axis,(-0.07,0.07) on the Y axis and (-0.12,0.32) on the Z axis.The 95％ LOA of the MSA in walking was (-4.40,4.74) on the X axis,(-17.35,4.14) on the Y axis and (-17.35,4.14) on theZ axis.For the MSV in walking itwas (-0.07,0.08) on the X axis,(-0.29,0.07) on the Y axis and (-0.12,0.18) on the Z axis.The 95％ LOAs of the variables representing their reliability and validity are small enough to be acceptable in clinical application.Conclusions The sacral marker method can be used in assessing the balance of stroke patients. Key words: Sacral marker method; Segmental representation; Center of gravity; Balance; Stroke; Reliability ; Validity

Visual reweighting in postural control is less adaptative in older adults

Postural control is based upon the fusion of sensory cues coming from multiple sources requiring continuously adaptation that may be altered due to aging, leading to the poor postural equilibrium in older adults. Therefore, the purpose of this study was to examine the adaptation in the relationship between the visual information and the body sway in older adults. Fifteen older (70 ± 7.6 years) and 15 younger adults (19 ± 1.1 years) stood upright inside of a moving room. Each participant performed 7 trials, each lasting 60 s, in which in the first 3 trials the room oscillated at 0.2 Hz, amplitude of 0.6 cm, and peak-to-peak velocity of 0.6 cm/s. In the fourth trial, the room oscillated at 0.2 Hz but with amplitude of 3.5 cm and peak-to-peak velocity of 3.5 cm/s. In the following 3 trials, the room oscillated with the same parameters of the first three trials. Body sway magnitude was examined through mean sway amplitude, and the relationship between visual information and induced body sway was examined through coherence and gain. Visual manipulation induced corresponding body sway in both older and younger adults, with no difference being observed between groups in the first three trials. In the fourth trial, mean sway amplitude, coherence and gain values were higher for the older compared to younger adults. Moreover, in the last three trials, older adults still showed higher gain values than observed for the younger adults. Taken together, these results suggest that older adults adapt to abrupt changes in visual cues, but not with the same magnitude as younger adults. Yet, older adults do not take advantage of experienced sensory changes in order to adapt the use of the vision information in the following experiences, indicating the less capability of adaptation to the sensory changes.

Influência da informação sensorial adicional no treinamento sensório-motor

O objetivo deste estudo foi investigar o efeito do treinamento sensório-motor, com e sem a utilização de informação sensorial adicional do tipo tira subpatelar, no controle postural de indivíduos sadios. Trinta adultos jovens e sadios participaram deste estudo, divididos aleatoriamente em três grupos: controle (GC), experimental sem informação sensorial adicional (GE) e experimental com informação sensorial adicional (GEI). Os participantes realizaram a tarefa de apoio monopodal, com olhos fechados, sobre uma plataforma de força, em duas condições sensoriais: 1) condição de informação normal - sem inclusão de informação sensorial adicional; e 2) condição de informação adicional - utilização de tira sub-patelar. A partir dos dados da plataforma de força foram calculadas as variáveis: amplitude e velocidade média de oscilação do centro de pressão (CP). Os participantes dos grupos experimentais realizaram dez sessões de treinamento sensório-motor com prancha de equilíbrio, com ou sem a utilização de informação sensorial adicional, de acordo o grupo definido. Os participantes dos grupos experimentais apresentaram redução da amplitude e velocidade média de oscilação do CP após o treinamento sensório-motor (p&lt;0,05). Além disto, foi identificada diferença significante entre os grupos experimentais (p&lt;0,05). Em conclusão, o treinamento sensório-motor melhora o controle postural de indivíduos sadios e estes efeitos são maximizados com a utilização de informação sensorial adicional.