Effect of support surface stability on balance in the elderly with mild cognitive impairment under different visual input conditions / 中国组织工程研究

BACKGROUND:Stability of the support surface and visual input are important factors affecting static balance,but most of the studies on the balance ability of elderly with mild cognitive impairment have focused on the stable hard support surface,and the control of static balance on the unstable support surface under different visual input conditions is not known. OBJECTIVE:To investigate the static balance ability of the elderly with mild cognitive impairment on soft and hard support surfaces under different visual input conditions. METHODS:Twenty-one elderly people with mild cognitive impairment and nineteen elderly people with normal cognition were selected for the study,and the Kistler three-dimensional dynamometer was used to conduct four tests:standing with two feet on hard support surface with eyes open,standing with two feet on soft support surface with eyes open,standing with two feet on hard support surface with eyes closed,standing with two feet on soft support surface with eyes closed,and standing with two feet on soft support surface with eyes closed,and the duration of each test was 30 seconds.The plantar center of pressure data were collected and compared between the two groups under different visual conditions on the soft and hard support surfaces. RESULTS AND CONCLUSION:(1)Under the condition of visual input,the total excursions(soft support surface:P=0.003),the total excursions-medial-lateral sides(soft support surface:P=0.001,hard support surface:P<0.001)and the 95%confidence ellipse area(soft support surface:P=0.001,hard support surface:P<0.001)of the center of pressure in the elderly with mild cognitive impairment on the soft and hard support surfaces were significantly higher than those of the elderly with normal cognition.(2)In the absence of visual input,the root mean square distance(P=0.014),the root mean square distance-medial-lateral sides(P=0.014),and the 95%confidence ellipse area(P=0.001)of center of pressure in the elderly with mild cognitive impairment on the soft support surfaces were significantly higher than those of the elderly with normal cognition,but there were no significant differences between the groups on the hard support surface(P>0.05).(3)These findings confirm that compared with the elderly with normal cognition who could make full use of visual sensory input to maintain body balance on the soft and hard support surfaces,mild cognitive impairment elderly presented a deficit in balance function.In particular,mild cognitive impairment elderly relied more on ankle proprioception to maintain balance when visual interference was present,suggesting that mild cognitive impairment elderly should focus on strengthening ankle proprioceptive training.

Characteristics of calcaneal inclination of children in the upright standing position / 体力科学

Calcaneal inclination in children may influence their standing posture. However, the calcaneal inclination of modern children is unclear. This study aimed to clarify the characteristics of calcaneal inclination and its effects on spinal alignment and the center of pressure (COP) position in children. The study included 402 elementary school children (208 boys, 194 girls). The variables measured included calcaneal inclination, lower leg lateral inclination angle, spinal alignment, and COP position. The mean calcaneal inclination was 4.40 ± 3.5°, indicating mild eversion. Calcaneal inclination was classified into calcaneal eversion (+), calcaneal introversion (-), and a mid-heel position. Overall, 3.7% (15/402) of the subjects had bilateral calcaneal introversion (-), 18.2% (73/402) had unilateral calcaneal introversion (-), and 21.9% (88/402) had calcaneal introversion (-). An examination of the relationship between calcaneal inclination and each measured variable showed a significance level of <5% between calcaneal inclination and age, height, and body weight, but the correlation coefficients were <0.2 each, indicating little correlation. However, a significant correlation was found between right and left calcaneal inclination and the right and left lower leg lateral inclination angles. Overall, 21.9% (88/402) of the elementary school children had calcaneal inclination in a standing posture. These results suggest that calcaneal inclination may not affect spinal alignment and COP position.

Effect of core stability training on dynamic balance and surface electromyography after anterior cruciate ligament reconstruction / 中国康复理论与实践

ObjectiveTo explore the effect of core stability training on dynamic balance and surface electromyography (sEMG) after anterior cruciate ligament reconstruction (ACLR), and to analyze the correlation between balance index and sEMG. MethodsFrom March to December, 2022, 32 patients with ACLR in Yantai Affiliated Hospital of Binzhou Medical University were randomly divided into control group (n = 16) and experimental group (n = 16). The control group accepted routine rehabilitation treatment, and the experimental group added core stability training, for six weeks. They were evaluated with American Hospital for Special Surgery Knee Score (HSS) and International Knee Documentation Committee Knee Score (IKDC), and the dynamic balance function and sEMG were measured before and after treatment, and the correlation between dynamic balance index and root mean square (RMS) of sEMG was analyzed. ResultsAfter treatment, the scores of HSS and IKDC increased significantly in both groups (|Z| > 3.526, |t| > 63.544, P < 0.001), and were better in the experimental group than in the control group (Z = -2.392, t = 2.650, P < 0.05); the length of gait line and single support line increased significantly, the medial-lateral displacement displacement decreased (|t| > 2.368, Z = -3.516, P < 0.05), and they were better in the experimental group than in the control group (|t| > 2.497, Z = -3.091, P < 0.05); the RMS of gluteus maximus and gluteus medius increased in the experimental group (t = -5.900, Z = -2.741, P < 0.01), and were better than those in the control group (t = 3.930, Z = -3.260, P < 0.01). After treatment, the RMS of gluteus maximus and gluteus medius in both groups were positively correlated with gait line length and single support line length, and were negatively correlated with medial-lateral displacement (|r| > 0.502, P < 0.01). ConclusionCore stability training could significantly improve knee joint function and dynamic balance, and enhance the activation of gluteus maximus and gluteus medius. Dynamic balance is highly correlated with sEMG.

Valores referenciales de posturografía basada en Nintendo Wii en población chilena

Resumen Introducción: La posturografía es un método de exploración complementario para valorar el grado de desplazamiento del centro de gravedad (COP); no debe usarse de forma aislada al evaluar equilibrio, pero se acepta para seguimiento de la respuesta a tratamiento. Es de baja disponibilidad, por su alto costo comercial. Como alternativa se documenta la plataforma Wii Balance Board (WBB) de Nintendo para registro posturográfico. Objetivo: Describir valores de normalidad en parámetros posturográficos en población chilena sin patología vestibular, usando un registro simple y accesible. Material y Método: Estudio transversal de valores referenciales en herramienta para evaluación del equilibrio. Se registraron valores posturográficos con versión adaptada del Sensory Organization Test (SOT) a adultos sanos. Mediciones con software WBB Sway Program mediante WBB. Se midieron índices somatosensorial, visual y vestibular, y patrones de control postural en ejes anteroposterior y mediolateral durante SOT-adaptado. Resultados: Se obtuvieron valores de velocidad de desplazamiento del COP, área del COP y desviaciones estándar correspondientes para 4 situaciones del SOT-adaptado de 35 sujetos entre 18-65 años, 21 mujeres, 14 hombres. Discusión: WBB permitió evaluar estos parámetros en población sana, como aproximación a determinar rangos de referencia. Esta herramienta de uso rápido y accesible constituye una alternativa útil para determinar patrones de control postural en sujetos sanos. Presentamos valores a utilizar como rango referencial en nuestra población; se sugiere utilizar estos valores como objetivo terapéutico en rehabilitación vestibular en pacientes evaluados en conjunto con otros parámetros clínico-sintomáticos.

Abstract Introduction: Posturography is a complementary method for evaluating the center of pressure (COP) displacement; it should not be used in isolation when assessing balance, but it is accepted for follow-up of the treatment response. Due to its high commercial cost and low availability, we documented the Nintendo Wii Balance Board (WBB) as an alternative for posturography. Aim: To describe the normal range of posturography parameters in the Chilean population without vestibular pathology, using a simple and accessible registry method. Material and Method: Cross-sectional study of referential values in a balance assessment tool. Posturography values were registered using an adapted version of the Sensory Organization Test (SOT) on healthy adults. Measurements with WBB Sway Program software through WBB. With adapted-SOT, somatosensory, visual and vestibular indices, as well as anterior/posterior and mediolateral axes postural control patterns, were measured. Results: Values of displacement velocity of the COP, COP area and corresponding standard deviations were obtained for 4 SOT-adapted situations from 35 subjects between 18-65 years, 21 women, 14 men. Discussion: As an approach to determine referential range values, WBB allowed to evaluate these parameters in healthy population. To determine healthy subjects postural control patterns this quick and accessible tool is a useful alternative. We present referential range values to use in our population; it is suggested to use these values as therapeutic objectives in vestibular rehabilitation in patients evaluated along with other clinical-symptomatic parameters.

Effects of Shoe Type and Walking Speed on Knee Joint Loads / 医用生物力学

Objective To investigate the effects of shoes type (barefoot, ordinary running shoes, minimalist shoes) and walking speed (jogging, walking at normal speed) on biomechanical parameters of knee joint, so as to provide theoretical reference for scientific fitness. Methods Vicon three-dimensional （3D） motion capture system and Kistler 3D force plate were used to collect biomechanical parameters of lower limbs from 10 subjects during walking at different speed with different shoes. Two-way (2 walking conditions × 3 shoe conditions) repeated measures analysis of variance was used to statistically analyze each dependent variable. Results Compared with jogging, the lateral excursion of plantar center of pressure (COP) was greater, the moment arm in frontal plane, the adduction moment and peak loading rate of knee joint were smaller, but the angular impulse of knee joint in frontal plane was greater. Compared with ordinary running shoes, the stride length was decreased, the lateral excursion of COP was greater, and the moment arm of knee joint in frontal plane, the knee adduction moment, the peak load rate and the angular impulse of knee joint in frontal plane were smaller. Conclusions In order to reduce the angular impulse and peak loading rate of knee joint in frontal plane, it is recommended to jog with small strides for ordinary people with minimalist footwear.

Testing System for Analyzing Directionally-specific Postural Adjustments Indued by Plantar Vibratory Stimulation / 中国康复理论与实践

Objective:To construct a testing system for the effects of plantar surface vibration stimulation on the human postural adjustments, and to explore its practicability. Methods:The mechanical device and control system providing vibration stimulation were designed and built. Twenty-five healthy teachers and students (aged 19~29 years) were recruited from our college to participate in the experimental study from 2nd to 6th, October, 2019. The amplitudes of postural response were compared following non-stimulation and stimulation at left forefoot, left heel, right forefoot, right heel, left foot, right foot, double forefoot, double heels of each subject at the 20 Hz, 40 Hz, 60 Hz and 80 Hz vibrations, respectively. Results:The amplitude of the center of pressure response under foot cutaneous stimulation increased compared with the response amplitude under non-vibration conditions (P < 0.05). Conclusion:The locations of vibration as well as different vibration parameters (such as frequency, amplitude) could be adjusted, and the information of postural response to vibratory stimulation of the plantar surface, especially the excursion of center of pressure could be collected in the system which can be applied in the experimental study on the human posture control.

Test-Retest Reliability Of Wavelet-Based Specific Frequency Bands Of Postural Control During Two Standing Task Conditions

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

A Partial Functional Restoration After Hallux Valgus Correct Surgery - A Controlled Preliminary Study

Introduction: Hallux valgus is the most common condition found in the foot, caused by a progressive failure of the first ray stabilization means. The hallux is deviated into valgus, the first metatarsal into varus, and their association leads to a subluxation of the metatarsophalangeal joint of the first ray. Surgery is a treatment frequently used to correct this condition. So, is the static postural balance altered after corrective surgery? Materials and Method: 23 subjects participated in the study, all women, divided into two groups: control and hallux valgus. The hallux valgus group was evaluated three months post-operatively. Bipodal tests were carried out on a stabilometry platform, one with eyes open and one with eyes closed. The pressure center parameters were recorded and analyzed, such as the length or the area of the pressure center. Results: The results obtained showed significant differences between the two groups and were statistically significant, with a p-value of 0,05. The pressure center values are higher in the hallux valgus group. Conclusion: Some results found in the literature agree with the results of the present study. There are significant deficits in the static postural balance three months after corrective surgery. Other studies with a larger sample may be performed to confirm or not the results of this study.

Inicialização da marcha no desenvolvimento do andar independente em crianças de 1. 3 anos a 4 anos: estudo preliminar / Stepping iniitiation of gait pattern development of children aged 1. 3 years to 4 years: preliminary study / Inicialización de la marcha en el desarrollo del andar independiente en niños de 1. 3 años a 4 años: estudio preliminar

O processo de transição da postura em pé parada para a caminhada cíclica é chamado de inicialização da marcha. Esse processo exige ajustes posturais antecipatórios. Porém, pouco se sabe sobre como es- ses ajustes se desenvolvem à medida que crianças pequenas adquirem a marcha independente. Assim, este é um estudo transversal com o obje- tivo de descrever o processo de inicialização da marcha em crianças de desenvolvimento típico, com idades entre 1.3 e 4 anos. Sessenta crianças de ambos os sexos de um Centro Municipal de Educação Infantil, devida- mente autorizadas pelos pais ou responsáveis, participaram voluntaria- mente do estudo. As crianças compuseram quatro grupos etários de 15 participantes: G1(1.3 anos de idade), G2 (2 anos de idade), G3 (3 anos de idade) e G4 (4 anos de idade). Uma plataforma de força dupla portátil foi utilizada para a obtenção do comportamento do centro de pressão (COP) durante a transição da posição em pé para o primeiro passo. Cada crian- ça realizou cinco tentativas da inicialização da marcha, que compreendia sair da posição em pé parada sobre a plataforma de força dupla com os pés afastados. Após o sinal sonoro, iniciava a atividade com o pé direito para fora da plataforma e continuava a andar até o fim de uma passarela pré-determinada, a uma velocidade autosselecionada. Os resultados fo- ram descritos conforme as fases da inicialização da marcha para as faixas etárias. As crianças com 1.3 anos apresentaram menor deslocamento an- teroposterior do COP (COPAP_1: p<0.001, COPAP_2: p <0.001 ) e maior ve- locidade de deslocamento do COP anteroposterior (VELAP_1: p <0.001 e VELAP_2: p <0.001), quando compradas com as dos grupos de crianças de 2, 3 e 4 anos, enquanto as crianças de 4 anos demonstram uma tendência de aumento do deslocamento anteroposterior COP e diminuição da velo- cidade de deslocamento do COP, quando em comparação às crianças de 1.3 anos. O aumento do valor no deslocamento do COPAP, juntamente com a diminuição da velocidade de deslocamento do COP entre as crian- ças de 1.3 anos, 2 anos, 3 anos e 4 anos, sugerem que o comportamento antecipatório para a inicialização da marcha se desenvolve primeiro no plano frontal (AP) e que, com o desenvolvimento do andar independen- te, melhora a estabilidade postural necessária para alcançar totalmente o controle para a execução da inicialização da marcha quando adquire o padrão maduro aos 7 anos de idade.

The process of transitioning from standing posture to cyclic gait is called gait initiation. This requires anticipatory postural adjustments. However, little is known about how these adjustments develop as young children acquire independent gait. Thus, this is a cross-sectional study with the objective of describing the process of gait startup in children of typical development aged between 1.3 and 4 years. Sixty children of both sexes from a Centro Municipal de Educação Infantil (CMEI) duly authorized by parents or guardians voluntarily participated in the study. Children comprised four age groups of 15 children G1(1.3 years of age), G2 (2 years of age), G3 (3 years of age) and G4 (4 years of age). A portable dual force plataform (AMTI model ASC-DUAL L201, AMTI, USA) was used to acquire pressure center behavior (COP) during the transition from standing position to first step, called gait initiation. Each children made five attempts at the start of the march, which included standing standing on the dual force platform with their feet away, after the beep started the activity with the right foot off the platform and continued to walk to the end of a predetermined walkway, at a self-selected speed. The results demonstrate the presence of a motor sequence characterized by increased development of the movement of the body forward lower displacement of cop and decreased cop displacement speed in all groups of children studied. Children 1.3 years old demonstrated lower anteroposterior displacement of cop (COPAP_1: p<0.001, COPAP_2: p <0.001 ) and higher displacement speed of anteroposterior COP (VELAP_1: p <0.001 and VELAP_2: p <0.001), while 4-year-olds demonstrate a trend of increased anteroposterior COP displacement and decreased cop displacement speed compared to 1.3-year-old children. The increase in the value of copap displacement, along with the decrease in cop displacement speed among children aged 1.3 years to 4 years, suggest that anticipatory gait-starting behavior develops first in the frontal plane (AP) and that with the development of the independent floor improves the postural stability necessary to fully achieve control for the execution of gait startup when it acquires the mature standard at 7 years of age.

El proceso de transición de la postura de pie a la marcha cíclica se llama inicio de la marcha. Esto requiere un ajuste postural anticipatorio. Sin embargo, poco se sabe acerca de cómo estos ajustes se desarrollan a medida que los niños pequeños adquieren marcha independiente. Así, se trata de un estudio transversal con el objetivo de describir el proceso de puesta en marcha de la marcha en niños de desarrollo típico de entre 1,3 y 4 años. Sesenta hijos de ambos sexos de un Centro Municipal de Educación Infantil debidamente autorizado por los padres o tutores participaron voluntariamente en el estudio. Los niños estaban compuestos por cuatro grupos de edad de 15 niños G1(1,3 años de edad), G2 (2 años de edad), G3 (3 años de edad) y G4 (4 años de edad). Una plataforma portátil de doble resistencia (modelo AMTI ASC- DUAL L201, AMTI, EE. UU.) se utilizó para adquirir el comportamiento del centro de presión (COP) durante la transición de la posición de pie al primer paso, llamado arranque de marcha. Cada niño hizo cinco intentos al comienzo de la marcha, que incluyó estar de pie en la plataforma de doble fuerza con los pies alejados, después de que el pitido comenzó la actividad con el pie derecho fuera de la plataforma y continuó caminando hasta el final de una pasarela predeterminada, a una velocidad auto- seleccionada. Los resultados demuestran la presencia de una secuencia motora caracterizada por un mayor desarrollo del movimiento del cuerpo hacia adelante menor desplazamiento de la policía y disminución de la velocidad de desplazamiento del cop en todos los grupos de niños estudiados. Los niños de 1,3 años demostraron un menor desplazamiento anteroposterior del policía (COPAP_1: p<0.001, COPAP_2: p <0.001 ) y mayor velocidad de desplazamiento de la COP anteroposterior (VELAP_1: p <0.001 y VELAP_2: p <0.001), mientras que los niños de 4 años demuestran una tendencia de aumento del desplazamiento de la COP anteroposterior y disminución de la velocidad de desplazamiento del copo en comparación con los niños de 1,3 años. El aumento del valor del desplazamiento de copap, junto con la disminución de la velocidad de desplazamiento de la policía entre los niños de 1,3 años a 4 años, sugieren que el comportamiento anticipatorio de arranque de la marcha se desarrolla primero en el plano frontal (AP) y que con el desarrollo del piso independiente mejora la estabilidad postural necesaria para lograr plenamente el control para la ejecución de la puesta en marcha de la marcha cuando adquiere el estándar maduro a los 7 años de edad.

Relationship between proprioception and postural stability of lower limbs in healthy adults / 中国组织工程研究

BACKGROUND: Proprioception is one of the many factors affecting posture stability, but the relationship and differences between proprioception and stability of the lower extremities remain unclear. OBJECTIVE: To investigate the differences of static stability and proprioception between dominant and non-dominant legs and the correlation between proprioception and stability in healthy adults without the influence of foot posture. METHODS: Sway length (SL) and sway area (SA) of the center of pressure (COP) were measured in 30 healthy adults with neutral feet standing on both legs and one leg, and the mean trajectory error (ATE) and completion time (CT) of lower limbs were recorded during proprioception evaluation. The study was approved by the Ethics Committee of Guangdong Second Traditional Chinese Medicine Hospital [No. (2019)50], and all participants voluntarily signed informed consent before the initiation of the study. RESULTS AND CONCLUSION: The ATE of the dominant leg was larger than that of the non-dominant leg (P < 0.05). There were significant correlations between left and right legs in proprioception and stability (P < 0.05 or 0.01). The associations between SL in left legs and ATE in right legs and between SL in right legs and ATE in left legs (P < 0.05) were significantly adjusted for the intrinsic differences of proprioception and stability. There was a significant correlation between SL standing with dominant legs and SL in two legs static standing (P < 0.05). Therefore, the proprioception of the dominant legs was significantly worse than that of the non-dominant legs, but there was no difference in their stability. To conclude, the stability of the lower limbs is not only related to the proprioception at the same side, but also to the proprioception at the opposite side. In the process of training and clinical rehabilitation therapy, if we hope to improve stability and proprioception of the lower limbs, we should not only strengthen training of the ipsilateral limb, but also pay attention to the contralateral proprioception.

Change in Static Postural Stability after a Home‑based Exercise Program in Persons with Idiopathic Parkinson’s Disease - A Randomized Control Study

Introduction and Purpose:The most common form of parkinsonism is idiopathic Parkinson’s disease. The cardinal symptoms of idiopathicParkinson’s disease are tremor, rigidity, bradykinesia, posture and gait abnormalities, speech changes, depression, gastrointestinal issues,urinary problems, autonomic features, eye abnormalities, cognitive impairments, cranial nerve dysfunction, and swallowing dysfunction.Abnormalities of posture significantly affect activities of daily living in such patients. Static posturography is used to measure the balanceof an individual during standing. Asingle-blinded controlled trial comparing 4 weeks of outpatient physical therapy with no specific therapyshowed significant improvement in gait in patients with Parkinson’s disease. However, the gains were lost when the patients stoppedexercises at the end of the program. Hence, the authors felt that teaching a simple, implementable home-based exercise could benefitthese patients in improving their balance. Any change in static balance could be measured easily with a force platform.Methodology: A total of 62 clinically diagnosed patients with idiopathic Parkinson’s disease attending a tertiary care centerwere randomized into two groups, one rehabilitation group (those who were taught a simple home-based rehabilitation exerciseprogram on an outpatient basis) and a non-rehabilitation (control) group who were not taught the exercises. They were clinicallyevaluated and their center of pressure (COP) sway area was measured using a computerized static posturography instrument(force platform), at first visit, after 1 month, after 3 months, and after 5 months. The differences in their COP sway area betweenthe visits were compared between the two groups to see the change in postural stability.Results and Discussion: Atotal of 62 patients who satisfied the inclusion criteria were inducted in the study after informed consent. Themean age of the rehabilitation group (n = 32) was 58.66 years and the mean age of the non-rehabilitation group (n = 30) was 59.17 years.69% of the rehabilitation group were males and 31% were females, and in the non-rehabilitation group, 67% were males while 37%were females. The mean duration of disease in the rehabilitation group was 8.31 years and that in the non-rehabilitation group was8.67 years. Most of the variables did not show any significant difference, and hence, the groups were comparable. The baseline meanCOP sway area of the rehabilitation group was 76.53 mm2 and that of the non-rehabilitation group was 76.73 mm2. There was a 11.68%decrease in the COP sway area of the rehabilitation group at the end of the 1st month while the non-rehabilitation group had only 0.22%decrease. At the end of the study, i.e., at 5th month, there was a 32.05% decrease in the sway area from baseline in the rehabilitationgroup, indicating significant improvement in static balance. There was only 1.13% decrease in the sway area of the non-rehabilitationgroup. Both the P values were <0.001, and thus, our study revealed that a simple home-based rehabilitation exercise program taughton an outpatient basis to patients with idiopathic Parkinson’s disease can improve the balance in such patients.Conclusion: There was a statistically significant improvement in the static postural stability of patients with idiopathic Parkinson’sdisease who did exercise at home when compared to those who did not perform the home-based exercises. However, longterm studies need to be done to confirm whether this gain is long lasting.

Assessment of Gait Stability using Acceleration Signal / 医用生物力学

Objective To analyze human gait stability by acceleration signal at the head and lumbar under different walking conditions, and make comparison with parameters by the traditional COM (center of mass)-COP(center of pressure) method, so as to discuss the reliability of applying wearable sensors to analyze human gait stability. Methods The harmonic ratio (HR) parameter at the head and lumbar based on acceleration signal was applied to analyze gait stability of 18 healthy young adults under 3 walking conditions (footwear normal walking, barefoot normal walking and barefoot walking at different velocities), and the results were compared with the assessment results from the COM-COP method. Results Walking at normal velocity was most stable, with the maximum HR parameter. Compared with footwear walking, HR parameters were significantly decreased (P＜0.05) during barefoot walking, indicating that gait stability was reduced. The results were consistent with the assessment results from the COM-COP method. Considering the factors of walking velocity and footwear, the gait stability parameters obtained by the two methods showed a significant negative linear correlation (R2＞0.50). Lumbar HR parameter and COM-COP parameters showed a stronger linear correlation (R2＞0.65). Conclusions The application of acceleration signal-based analysis algorithm could effectively and reliably evaluate the stability of human gait, and acceleration at the lumbar was more sensitive than the head signal for analyzing gait stability.

Single-leg Static Postural Balance in Individuals with or Without Unilateral Functional Ankle Instability / 中国运动医学杂志

Objective To explore the static postural balance in individuals with or without functional ankle instability (FAI)by identifying and quantifying the spatial characteristics of center of pressure (COP),as well as rambling and trembling trajectory properties.Methods Twelve FAI patients was selected into the FAI group,while another 14 healthy students were chosen into the control group.The single-leg standing test with and without vision was conducted on the unstable side of the FAI group and the non-dominant side of the control group 3 trials with each trial lasting 30 s.The displacement of COP and the time and frequency domain of rambling and trembling were analyzed and compared between the two groups.Results There was no significant difference in the displacement of COP with opened eyes(P＞0.05).The area and the anterior-posterior length of COP of the FAI group were larger than those of the control group with eyes closed (P＜0.05).For the rambling and trembling trajectory,no significant differences were found in all the time domains between the two groups with eyes open or closed(P＞0.05),except the mean sway amplitude(MSA)(P＜0.05).Moreover,the mean square root and standard deviation of MSA of the FAI group were significantly bigger than the control group(P＜ 0.05).Significant differences were found in the MSA frequency between open and closed eyes(P＞0.05),but not between the FAI and control groups(P＜0.05).Conclusions The FAI patients are weaker than healthy people not only in the peripheral control,but also in the central control of the static postural balance.Therefore,injuries in the central neural system must also be considered when analyzing the reason for FAI.The imbalance of the FAI patients can be avoided by opening eyes.

Reliability and minimal detectable change of between-limb synchronization, weight-bearing symmetry, and amplitude of postural sway in individuals with stroke

Abstract Introduction: Recently, variables related to between-limb synchronization of the centers of pressure (COP) have been proposed as measures of postural control in post-stroke patients. Although it is crucial in verifying their potential clinical use, the reliability of these variables is unknown. The aim of this work was to determine the reliability and minimal detectable change (MDC) of the peak of synchronization (ρmax) in the anteroposterior (AP) and mediolateral (ML) directions, the time lag for the peak (ρmaxlag), synchronization at lag zero (ρ0), weight-bearing symmetry, and amplitude of postural sway, measured as the root mean square (RMS) values of the COP displacements in both directions (AP and ML COP displacement). Methods COP data of 16 participants with stroke were collected at quiet standing with two force plates at two sessions separated by 2 to 7 days. The procedure was repeated three times in each session. The within and between sessions reliability was determined by the intraclass correlation coefficient (ICC), and the MDC was obtained from the ICC between sessions. Results The variables ρmaxlag in the AP and ML directions, as well as ρ0 in the AP direction, exhibited poor within session reliability (ICC ≤ 0.4). The findings revealed excellent within and between sessions reliability (ICC ≥ 0.89) for weight-bearing symmetry and the RMS displacement in the AP direction, with MDC values of 5% and 2.07 mm, respectively. The remaining variables exhibited moderate reliability. Conclusion Weight-bearing symmetry and AP COP displacement can be considered reliable variables for use in clinical practice.

Effects of plantar foot sensitivity manipulation on postural control of young adult and elderly / Efeitos da manipulação da sensibilidade plantar sobre o controle da postura ereta em adultos jovens e idosos

ABSTRACT Introduction: Subjects with sensorial losses present balance deficits. Although such condition is often observed among elderly, there is discussion concerning the dependence on sensorial information for body sway control in the elderly without sensorial losses. Purpose: We investigated the effects of foot sensitivity manipulation on postural control during upright standing in young adults and independent elderly (n = 19/group). Methods: Plantar sensitivity was evaluated by esthesiometry, and speed of center of pressure shift data during upright posture were evaluated for each foot using a baropodometer while the subjects were standing with eyes open or closed. The young adult group was evaluated for center of pressure in normal conditions and after plantar sensitivity disturbance, by immersing their feet in water and ice. Results: Young adults did not show alterations in their center of pressure after sensorial perturbation and presented, even under sensorial perturbation, better postural control than elderly subjects. The elderly showed lower foot sensitivity and greater center of pressure oscillation than young adults. Conclusion: Elderly subjects seem to rely more on foot sensitivity for control of body sway than young adults. In the elderly, a clinical intervention to improve foot sensitivity may help in upright posture maintenance.

RESUMO Introdução: Pessoas com perdas sensoriais apresentam déficits de equilíbrio. Embora esse quadro seja comum em idosos, ainda se discute o quanto idosos sem doenças que afetam as vias sensoriais dependem dessa informação para controlar oscilações corporais durante o controle da postura. Objetivo: Investigar os efeitos da perturbação da sensibilidade plantar sobre o controle da postura ereta em adultos jovens e idosos independentes (n = 19/grupo). Métodos: A sensibilidade plantar foi avaliada com estesiômetro e dados de velocidade e deslocamento do centro de pressão durante a postura de pé foram avaliados para cada pé com um baropodômetro, em condições de olhos abertos e fechados. O grupo de adultos jovens foi avaliado quanto ao centro de pressão nas condições normal e pós-perturbação da sensibilidade plantar, pela imersão dos pés em água e gelo. Resultados: Adultos não apresentaram alterações no centro de pressão em resposta à perturbação sensorial e tiveram, mesmo na condição de perturbação sensorial, melhor controle postural do que idosos. Idosos apresentaram menor sensibilidade plantar e maior oscilação do centro de pressão do que os adultos jovens. Conclusão: Idosos pareceram depender mais da sensibilidade plantar para manter o controle postural do que adultos jovens. Em idosos, intervenções clínicas que melhorem a sensibilidade plantar podem auxiliar na tarefa de manter a postura de pé.

Developing a dynamic virtual stimulation protocol to induce linear egomotion during orthostatic posture control test

Abstract Introduction In this work, the effect of a dynamic visual stimulation (DS) protocol was used to induce egomotion, the center of pressure (COP) displacement response. Methods DS was developed concerning the scenario structure (chessboard-pattern floor and furniture) and luminance. To move the scenario in a discrete forward (or backward) direction, the furniture is expanded (or reduced) and the black and white background is reversed during floor translation while the luminance is increased (or reduced) by steps of 2 cd/m2. This protocol was evaluated using COP signals from 29 healthy volunteers: standing on a force platform observing the virtual scene (1.72 × 1.16 m) projected 1 m ahead (visual incidence angle: θl = 81.4° and θv = 60.2°), which moves with constant velocity (2 m/s) during 250 ms. A set of 100 DS was applied in random order, interspersed by a 10 s of static scene. Results The Tukey post-hoc test (p < 0.001) indicated egomotion in the same direction of DS. COP displacement increased over stimulation (8.4 ± 1.7 to 22.6 ±5.3 mm), as well as time to recover stability (4.1 ± 0.4 to 7.2 ± 0.6 s). The peak of egomotion during DSF occurred 200 ms after DSB (Wilcoxon, p = 0.002). Conclusion The dynamic configuration of this protocol establishes virtual flow effects of linear egomotion dependent on the direction of the dynamic visual stimulation. This finding indicates the potential application of the proposed virtual dynamic stimulation protocol to investigate the cortical visual evoked response in postural control studies.

Interpretación de Variabilidad en la Postura Bípeda Quieta en edad Sensible al Sistema de Control / Interpretation of the variability of the steady bipedal posture in age sensitive to the system control

Resumen: El estudio del control postural humano mediante técnicas mecano-estadísticas, permite identificar comportamientos dinámicos con características de persistencia y anti-persistencia. Tales comportamientos, pueden ser interpretados como variabilidad tiempo dependiente en los sistemas de control y algunos indicadores que dan cuenta de éstos, son el coeficiente de difusión y el exponente de ajuste obtenidos con la técnica de Análisis de Difusión del Estabilograma (ADE). Se utilizó una plataforma de fuerza para los registros estabilométricos y se aplicó el ADE con el objeto de discriminar el comportamiento temporal de la variabilidad del centro de presión, en posición bípeda cuasi-estática con y sin restricción visual (Ojos cerrados y Ojos abiertos) en un grupo de 22 escolares en edad crítica (11,2±1,5 años) de maduración del proceso de control. Los resultados obtenidos en los coeficiente de difusión (Ds, DƖ) y exponentes de ajuste (Hs, HƖ ) en ambas condiciones visuales, caracterizan claramente comportamientos diferenciados para cada fases de la gráfica del ADE, y se establece diferencias significativas en los indicadores Ds y Hs, al comparar la excursión del COP con y sin restricción visual. El ADE nos permite identificar un comportamiento de sistema de control postural similar al de los adultos, modelado como un movimiento browniano fraccionario de dos fases.

Abstract: The human postural control study through statistical mechanic techniques identifies dynamic behavior with characteristics of persistence and anti-persistence. Such behaviors are interpreted like time-dependent variability of the control systems, and indicators that reflect these ones, are diffusion coefficient and scaling exponent obtained with stabilogram diffusion analysis (SDA) technique. A force platform was used to obtain stabilometry records and SDA was applied in order to discriminate the temporal behavior of the variability in quasi-static bipedal position in a group of 22 students in critical age (11,2 ± 1,5 years old) for postural control maturity, between eyes-closed and eyes-open conditions. The results of diffusion coefficients (Ds, DƖ ) and scaling exponents (Hs, HƖ ) in both visual condition have two distinct phases from ADE graphic and establish statistically significant differences for D s and H s, when comparing the displacement of COP between open eyes and closed eyes. The SDA allows us to identify a behavior of postural control system similar to adults, modeled like a two-phase fractional Brownian motion.

Positive correlation of postural balance evaluation by two different devices in community dwelling women / Correlação do desempenho do equilíbrio postural entre dois diferentes dispositivos em mulheres idosas

OBJECTIVE: To establish the convergent validity or relationship of the Balance Master® as balance assessment device by comparing its performance results with those obtained from the AccuSway Plus® force plate. METHOD: Cross-sectional observational study, without intervention, of 126 postmenopausal women (60.3 ± 3.2 years; body mass index = 27.6 ± 4.7 kg/m2). Two devices were used for the independent assessments of static balance: (a) Static postural balance assessment (posturography) was performed on a force platform (AccuSway Plus); (b) static evaluation was performed on the Balance Master®System. The variables studied in the two devices, were: (i) the Mean Velocity of the Center of Pressure Displacement in all directions (Vavg or Mean Firm), (ii) the Anteroposterior (Mean-Y) and (iii) the Mediolateral (Mean-X) Centers of Pressure Displacement. The Spearman correlation coefficient was calculated to measure the correlation of the variables of balance obtained with the two different devices. RESULTS: Significant correlations were obtained when the relationships between both variables were described by fitting multiple linear regression models. There was an association between the mean velocity of center of pressure displacement in both devices, with eyes open (r = 0.21) and eyes closed (r = 0.47). In the eyes open condition, Vavg increased, on average, 0.26 units, while Mean Firm increased 1.0 unit; in the Mean-Firm; in eyes closed condition, Vavg increased, on average, 1.27 units, while Mean-Firm increased by 1,0 unit. CONCLUSION: The devices investigated presented a significant correlation for the mean velocity calculated from the total displacement of the center of pressure in all directions.

OBJETIVO: Estabelecer a validade convergente ou relação do Balance Master® como dispositivo de avaliação do equilíbrio, comparando seus resultados de desempenho com os obtidos a partir da plataforma de força AccuSway Plus®. MÉTODO: Trata-se de um estudo observacional transversal, sem intervenção, de 126 mulheres na pós-menopausa (60,3 ± 3,2 anos; índice de massa corporal = 27,6 ± 4,7 kg/m2). A avaliação de equilíbrio postural estático (posturografia) para todos os voluntários foi realizada inicialmente em uma plataforma de força (AccuSway Plus); uma segunda avaliação estática foi realizada em um dispositivo de equilíbrio Balance Master® Sistem. As variáveis estudadas nos dois dispositivos, foram: velocidade média do deslocamento total do centro de pressão em todas as direções (Vavg e Média-Form); ântero-posterior (YSD and Mean-Y) e médio-lateral (XSD and X-Mean) do centro de pressão de deslocamento. O coeficiente de correlação de Spearman foram calculados para medir a correlação entre as variáveis de equilíbrio obtidas nos dois dispositivos diferentes. RESULTADOS: Foi encontrada uma correlação significativa entre as duas variáveis, e foi ajustado por um modelo de regressão linear. Houve uma associação entre a velocidade média de deslocamento do centro de pressão em ambos os dispositivos em ambas as condições, os olhos abertos (r = 0,21) e fechada (r = 0,47). Na condição de olhos abertos, os Vavg aumenta, em média, 0,26 unidades, com um aumento de uma unidade no Mean-Form; na condição de olhos fechados, Vavg aumenta, em média, 1,27 unidades, com um aumento de uma unidade no Mean-Form. CONCLUSÃO: Os dispositivos investigados apresentaram uma correlação significativa para a velocidade média calculada a partir do deslocamento total do centro de pressão em todas as direções.

Static Balance Evaluated by Maximum Angle of Center of Mass-Center of Pressure in People of Different Ages / 中国康复理论与实践

@#Objective To compare the difference of static balance ability in different aged people, with the maximum angle of center of mass (COM) and center of pressure (COP). Methods 37 healthy people without cardiovascular and cerebrovascular diseases including 15 young people (18~40 years old), 10 middle age people (41~65 years old) and 12 old people (>65 years old) participated in this study. The maximum angle of COM-COP and the corresponding envelope areas were recorded in 4 standing posture: natural standing, close eyes standing, single leg standing and single leg standing with eyes closed. Results There was no significant difference in the maximum angle of COM-COP among 3 groups in 3 states (nature standing, close eyes standing, single leg standing with eyes closed) (P>0.05), but there was significant difference in the state of single leg standing (P<0.05) between the young and the old, and the middle-aged and the old. Conclusion The maximum angle of COM-COP in the state of single leg standing can sensitively detect the deterioration of stability of older people. It may be a new index of static balance in clinic.

Static Balance Evaluated by Maximum Angle of Center of Mass-Center of Pressure in People of Different Ages / 中国康复理论与实践

Objective To compare the difference of static balance ability in different aged people, with the maximum angle of center of mass (COM) and center of pressure (COP). Methods 37 healthy people without cardiovascular and cerebrovascular diseases including 15 young people (18~40 years old), 10 middle age people (41~65 years old) and 12 old people (>65 years old) participated in this study. The maximum angle of COM-COP and the corresponding envelope areas were recorded in 4 standing posture:natural standing, close eyes stand-ing, single leg standing and single leg standing with eyes closed. Results There was no significant difference in the maximum angle of COM-COP among 3 groups in 3 states (nature standing, close eyes standing, single leg standing with eyes closed) (P>0.05), but there was significant difference in the state of single leg standing (P<0.05) between the young and the old, and the middle-aged and the old. Conclu-sion The maximum angle of COM-COP in the state of single leg standing can sensitively detect the deterioration of stability of older people. It may be a new index of static balance in clinic.