Reorganização do stiffness em indivíduos com Acidente Vascular Encefálico face à intervenção em fisioterapia. Repercussões no levantar e na marcha

Introdução: A organização estrutural e funcional do sistema nervoso face à organização dos diferentes tipos de input, no âmbito da intervenção em fisioterapia, pode potenciar um controlo postural para a regulação do stiffness e com repercussões na marcha e no levantar. Objetivo: Descrever o comportamento do stiffness da tibiotársica no movimento de dorsiflexão, no membro inferior ispi e contralesional, em indivíduos após Acidente Vascular Encefálico, face a uma intervenção em fisioterapia baseada num processo de raciocínio clínico. Pretendeu-se também observar as modificações ocorridas no âmbito da atividade electromiográfica dos flexores plantares, gastrocnémio medial e solear, durante a marcha e o levantar. Métodos: Foi implementado um programa de reabilitação em 4 indivíduos com sequelas de AVE por um período de 3 meses, tendo sido avaliados no momento inicial e final (M0 e M1). O torque e a amplitude articular da tibiotársica foi monitorizada, através do dinamómetro isocinético, durante o movimento passivo de dorsiflexão, e o nível de atividade eletromiográfica registado, através de electomiografia de superfície, no solear e gastrocnémio medial. Foram estudadas as fases de aceitação de carga no STS (fase II) e na marcha (sub-fase II). Resultados: Em todos os indivíduos em estudo verificou-se que o stiffness apresentou uma modificação no sentido da diminuição em todas as amplitudes em M1. O nível de atividade eletromiográfica teve comportamentos diferentes nos vários indivíduos. Conclusão: O stiffness apontou para uma diminuição nos indivíduos em estudo entre M0 e M1. Foram registadas modificações no nível de atividade eletromiográfica sem que seja possível identificar uma tendência clara entre os dois momentos para esta variável.

Organização da atividade dos músculos solear e braquiorradial em sujeitos com AVE e aumento do stiffness do cotovelo

Introdução: Das possíveis alterações decorrentes da lesão por Acidente Vascular Encefálico (AVE) é de evidenciar as alterações de controlo postural (CP) e aumento do stiffness. A intervenção na reabilitação neuro-motora baseia-se na capacidade intrínseca do Sistema Nervoso Central (SNC) compensar danos estruturais através da reorganização das redes neurais. Objectivo(s): Descrever as modificações do comportamento e tempos de ativação dos músculos solear e braquiorradial no início da marcha e primeira subfase das sequências de movimento de sentado para de pé e de pé para sentado. Pretendeu-se apresentar também as modificações do stiffness do cotovelo Métodos: A amostra consistiu em 5 participantes com média de idade de 44 anos, 2 do sexo feminino e 3 do masculino que sofreram um AVE. Foi implementado um programa de reabilitação para cada, por um período de 3 meses, com 2 momentos de avaliação (M0 e M1). A eletromiografia foi recolhida do solear, braquiorradial, biceps e triceps. O dinamómetro isocinético monitorizou o torque e a amplitude do cotovelo na extensão passiva. Foram calculados os tempos de ativação muscular e o valor de stiffness. Resultados: Observou-se nos 5 participantes uma modificação do comportamento dos músculos solear e braquiorradial ipsilesional e contralesional no sentido da inibição de M0 para M1 no sentar levantar. Esta também foi observada na sequência de pé para sentado e no início da marcha, sendo mais variável entre participantes. Verificou-se que o stiffness do membro superior contralesional apresentou uma modificação no sentido da diminuição em todas as amplitudes. O mesmo sucedeu com membro superior ipsilesional sobretudo nas amplitudes intermédias, excepto no B e D. Conclusão: De M0 para M1 verificou-se a modificação dos tempos e do comportamento dos músculos antigravíticos como o solear e o braquiorradial nas tarefas funcionais e uma modificação do stiffness passivo do cotovelo.

Reorganização do Controlo Postural no Acidente Vascular Encefálico: Ajustes Posturais Antecipatórios e Stiffness da Tibiotársica

Introdução: A reorganização do Sistema Nervoso após Acidente Vascular Encefálico é dependente da experienciação de diferentes tipos de input no âmbito da intervenção em fisioterapia. A potenciação do controlo postural (CP) nestes sujeitos é importante para organização dos ajustes posturais antecipatórios nas tarefas funcionais levantar, sentar e início da marcha e pode ser acompanhado de uma regulação do stiffness. Objectivo(s): Reportar as modificações ocorridas nos tempos de inibição e ativação dos músculos solear e tibial anterior, respetivamente, nas sequências de movimento levantar, sentar e início da marcha, na linha temporal atribuída aos APA’s assim como descrever as modificações ocorridas no comportamento do stiffness passivo da tibiotársica. Métodos: Foi implementado um programa de fisioterapia durante 3 meses em 5 participantes com Acidente Vascular Encefálico. Estes foram avaliados previamente à implementação do programa e após (M0 e M1). Foi analisada a atividade eletromiográfica dos músculos solear e tibial anterior, em ambos os membros inferiores, na linha temporal atribuída aos APA’s nas referidas tarefas. O torque e a amplitude articular da tibiotársica foi monitorizada, através do dinamómetro isocinético, no movimento passivo de dorsiflexão, e registada a atividade muscular através de eletromiografia de superfície, nos músculos solear e gastrocnémio medial. Resultados: À exceção do músculo tibial anterior contralesional no paciente C, todos os participantes demonstraram modificações nos tempos dos músculos do membro contralesional na tarefa levantar. No membro ispsilesional todos os participantes demonstraram alterações, sem que seja possível definir uma tendência. Todos apresentaram uma diminuição do stiffness, embora nos participantes A e E mais evidente nas amplitudes intermédias. Conclusão: Entre os dois momentos de avaliação foi possível reportar modificações nos tempos de inibição dos músculos solear e nos tempos de ativação dos músculos tibial anterior na linha temporal atribuída aos APA’s, no entanto mais homogéneas no membro contralesional na tarefa levantar. Em todos os participantes o stiffness sofreu alterações no sentido da diminuição.

Does altering brachial artery tone with lower-body negative pressure and flow-mediated dilation affect arterial stiffness?

Although medium sized, muscular vessels normally respond to sympathetic stimulation by reducing compliance, it is unclear whether the large brachial artery is similarly affected by sympathetic stimulation induced via lower-body negative pressure (LBNP). Similarly, the impact of flow-mediated dilation (FMD) on brachial artery compliance and distensibility remains unresolved, hi addition, before such measures can be used as prognostic tools, it is important to investigate the reliability and repeatability of both techniques. Using a randomized order design, the effects of LBNP and FMD on the mechanical properties of the brachial artery were examined in nine healthy male subjects (mean age 24y). Non-invasive Doppler ultrasound and a Finometer were used to measure simultaneously the variation in systolic and diastolic diameter, and brachial blood pressure, respectively. These values were used to calculate compliance and distensibility values at baseline, and during both LBNP and FMD. The within-day and between-day repeatability of arterial diameter, compliance, distensibility, and FMD measures were assessed using the error coefficient and intra-class correlation coefficient (ICC). While heart rate (P<0.01) and peripheral resistance increased during LBNP (P<0.05), forearm blood flow and pulse pressure decreased (P<0.01). hi terms of mechanical properties, vessel diameters decreased (P<0.05), but both compliance and distensibility were not changed. On the other hand, FMD resulted in a significant increase in diameter (P<0.001), with no change in compliance or distensibility. hi summary, LBNP and FMD do not appear to alter brachial artery compliance or distensibility in young, healthy males. Whereas measures ofFMD were not found to be repeatable between days, the ICC indicated that compliance and distensibility were repeatable only within-day.

The association between body composition and arterial stiffness in peri-pubescent children

The objective of this study was to examine the association between body composition and arterial stiffuess in peri-pubescent boys and girls. Differences in arterial distensibility were measured in 68 children (45 normal weight, 12 overweight, and 11 obese) between the ages of9 to 12 years. Weight classification was based on age and gender-specific body mass index cut-offs, while pubertal maturation was self-reported using Tanner staging. Distensibility was determined using two-dimensional, B-Mode echo Doppler ultrasound to measure changes at the right common carotid artery (CCA) diameter changes, while carotid pulse pressure (cPP) was measured at the left CCA by applanation tonometry. One-way ANOV A analysis revealed significant differences (p<0.001) in all anthropometric measures between the normal weight and overweight children, as well as the normal weight and obese children. Body stature was only higher in obese children compared to normal weight children (p<0.01). No significant differences were found between groups regarding age or Tanner stage. Common carotid artery distensibility showed a significant difference (p<0.01) between normal weight children (0.008 ± 0.002 mmHg-1 ) compared to obese children (0.005 ± 0.002 mmHg-1 ), with a borderline significant difference between the normal and overweight subjects (p=0.06). There was no significant effect for gender between males and females across all independent variables. The strongest determinants of distensibility in children were cPP (r= -0.52, p

ARTERIAL STIFFNESS IN CHILDREN WITH AND WITHOUT DEVELOPMENTAL COORDINATION DISORDER

The purpose of this study was to determine whether children with potential developmental coordination disorder (p-DCD) demonstrate increased arterial stiffness and thickness compared to age and school matched controls (mean age 14.7 yrs). We also assessed whether these measures differed by sex. Compliance, distensibility, and intima-media thickness (IMT) were measured at the common carotid artery for 28 children with p-DCD and 47 controls. ECG-R-wave-toe pulse wave velocity (PWV) was also measured for 29 children with p-DCD and 45 controls. We found that compared to controls males with p-DCD had significantly higher PWV (3.8±0.2 vs. 4.1±0.3, p=0.001) and lower distensibility (0.82± 0.19 vs. 0.70± 0.17, p=0.034) while females showed no significant differences (p=0.523 and p=0.123 respectively). As a result, it is apparent that sex differences exist with respect to arterial health within this population and that children with p-DCD may be more likely to develop cardiovascular disease later in life.

Development of smart variable stiffness actuators using polymer hydrogels

In this work, compliant actuators are developed by coupling braided structures and polymer gels, able to produce work by controlled gel swelling in the presence of water. A number of aspects related to the engineering of gel actuators were studied, including gel selection, modelling and experimentation of constant force and constant displacement behaviour, and response time. The actuator was intended for use as vibration neutralizer: with this aim, generation of a force of 10 N in a time not exceeding a second was needed. Results were promising in terms of force generation, although response time was still longer than required. In addition, the easiest way to obtain the reversibility of the effect is still under discussion: possible routes for improvement are suggested and will be the object of future work.

Designs for an adaptive tuned vibration absorber with variable shape stiffness element

An adaptive tuned vibration absorber (ATVA) with a smart variable stiffness element is capable of retuning itself in response to a time-varying excitation frequency., enabling effective vibration control over a range of frequencies. This paper discusses novel methods of achieving variable stiffness in an ATVA by changing shape, as inspired by biological paradigms. It is shown that considerable variation in the tuned frequency can be achieved by actuating a shape change, provided that this is within the limits of the actuator. A feasible design for such an ATVA is one in which the device offers low resistance to the required shape change actuation while not being restricted to low values of the effective stiffness of the vibration absorber. Three such original designs are identified: (i) A pinned-pinned arch beam with fixed profile of slight curvature and variable preload through an adjustable natural curvature; (ii) a vibration absorber with a stiffness element formed from parallel curved beams of adjustable curvature vibrating longitudinally; (iii) a vibration absorber with a variable geometry linkage as stiffness element. The experimental results from demonstrators based on two of these designs show good correlation with the theory.

Design of redundant drive joint with adjustable stiffness and damping mechanism to improve joint admittance

Improving admittance of robotic joints is the key issue for making rehabilitation robots safe. This paper describes a design of Redundant Drive Joint (RD-Joint) which allows greater flexibility in the design of robotic mechanisms. The design strategy of the RD-Joint employs a systematic approach which consists of 1) adopting a redundant joint mechanism with internal kinematical redundancy to reduce effective joint inertia, and 2) adopting an adjustable admittance mechanism with a novel Cross link Reduction Mechanism and mechanical springs and dampers as a passive second actuator. First, the basic concepts used to construct the redundant drive joint mechanism are explained, in particular the method that allows a reduction in effective inertia at the output joint. The basic structure of the RD-Joint is introduced based on the idea of reduced inertia along with a method to include effective stiffness and damping. Then, the basic design of the adjustable admittance mechanism is described. Finally, a prototype of RD-joint is described and its expected characteristics are discussed.

Long chain n-3 PUFA-rich meal reduced postprandial measures of arterial stiffness

Background & aims The consumption of long chain n − 3 polyunsaturated fatty acids (LC n − 3 PUFA) is known to be cardio-protective. Data on the influence of LC n − 3 PUFA on arterial stiffness in the postprandial state is limited. The aim of this study was to investigate the acute effects of a LC n − 3 PUFA-rich meal on measures of arterial stiffness. Methods Twenty-five healthy subjects (12 men, 13 women) received a control and a LC n − 3 PUFA-rich meal on two occasions in a random order. Arterial stiffness was measured at baseline, 30, 60, 90, 120, 180 and 240 min after meal consumption by pulse wave analysis and digital volume pulse to derive an augmentation index and a stiffness index respectively. Blood samples were taken for measurement of lipids, glucose and insulin. Results Consumption of the LC n − 3 PUFA-rich meal had an attenuating effect on augmentation index (P = 0.02) and stiffness index (P = 0.03) compared with the control meal. A significant treatment effect (P = 0.036) was seen for plasma non-esterified fatty acids concentrations. Conclusions These data indicate that acute LC n − 3 PUFA-rich meal consumption can improve postprandial arterial stiffness. This has important implications for the beneficial properties of LC n − 3 PUFA and cardiovascular risk reduction.

Does dairy food intake predict arterial stiffness and blood pressure in men? Evidence from the Caerphilly prospective study

Arterial stiffness is an independent predictor of cardiovascular disease events and mortality, and like blood pressure, may be influenced by dairy food intake. Few studies have investigated the effects of consumption of these foods on prospective measures of arterial stiffness. The present analysis aimed to investigate the prospective relationship between milk, cheese, cream, and butter consumption and aortic pulse wave velocity, augmentation index, systolic and diastolic blood pressure, as well as cross-sectional relationships between these foods and systolic and diastolic blood pressure and metabolic markers using data from the Caerphilly Prospective Study. Included in this cohort were 2512 men, aged 45 to 59 years, who were followed up at 5-year intervals for a mean of 22.8 years (number follow-up 787). Augmentation index was 1.8% lower in subjects in the highest quartiles of dairy product intake compared with the lowest (P trend=0.021), whereas in the highest group of milk consumption systolic blood pressure was 10.4 mm Hg lower (P trend=0.033) than in nonmilk consumers after a 22.8-year follow-up. Cross-sectional analyses indicated that across increasing quartiles of butter intake, insulin (P trend=0.011), triacylglycerol (P trend=0.023), total cholesterol (P trend=0.002), and diastolic blood pressure (P trend=0.027) were higher. Across increasing groups of milk intake and quartiles of dairy product intake, glucose (P trend=0.032) and triglyceride concentrations (P trend=0.031) were lower, respectively. The present results confirm that consumption of milk predicts prospective blood pressure, whereas dairy product consumption, excluding butter, is not detrimental to arterial stiffness and metabolic markers. Further research is needed to better understand the mechanisms that underpin these relationships.

Is fatty acid intake a predictor of arterial stiffness and blood pressure in men? Evidence from the Caerphilly Prospective Study

Background and aims: Arterial stiffness is an independent predictor of cardiovascular disease (CVD) events and all-cause mortality and may be differentially affected by dietary fatty acid (FA) intake. The aim of this study was to investigate the relationship between FA consumption and arterial stiffness and blood pressure in a community-based population. Methods and results: The Caerphilly Prospective Study recruited 2398 men, aged 45-59 years, who were followed up at 5-year intervals for a mean of 17.8-years (n 787). A semi-quantitative food frequency questionnaire estimated intakes of total, saturated, mono- and poly-unsaturated fatty acids (SFA, MUFA, PUFA). Multiple regression models investigated associations between intakes of FA at baseline with aortic pulse wave velocity (aPWV), augmentation index (AIx), systolic and diastolic blood pressure (SBP, DBP) and pulse pressure after a 17.8-year follow-up - as well as cross-sectional relationships with metabolic markers. After adjustment, higher SFA consumption at baseline was associated with higher SBP (P = 0.043) and DBP (P = 0.002) and after a 17.8-year follow-up was associated with a 0.51 m/s higher aPWV (P = 0.006). After adjustment, higher PUFA consumption at baseline was associated with lower SBP (P = 0.022) and DBP (P = 0.036) and after a 17.8-year follow-up was associated with a 0.63 m/s lower aPWV (P = 0.007). Conclusion: This study suggests that consumption of SFA and PUFA have opposing effects on arterial stiffness and blood pressure. Importantly, this study suggests that consumption of FA is an important risk factor for arterial stiffness and CVD.