968 resultados para tipo de fibra muscular


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Os esportes de alto nível determinam padrões corporais que extrapolam barreiras geopolíticas, sociais e culturais. Estas peculiaridades resultam em alterações posturais que estão associadas à eficiência do gesto desportivo, porém, em longo prazo, podem evoluir para processos mórbidos que limitam a prática de atividades físicas regulares. O objetivo da pesquisa foi descrever o perfil postural dos atletas que participam de provas de potência muscular e identificar processos anátomo-cinesiológicos responsáveis pelas principais alterações corporais. A casuística foi composta por 15 atletas do sexo masculino, especializados em provas de potência muscular. O protocolo para coleta de dados foi elaborado com base na proposta de: i) Kendall, para o exame físico e observacional, utilizando simetrógrafo e fio de prumo; ii) Souchard, para a análise postural em cadeia. As informações foram organizadas sob a forma de distribuição de freqüência absoluta e relativa. Os resultados apontaram que: i) o tornozelo em valgo (67%) foi a situação mais comum; ii) a rotação interna da pelve à direita (60%), seguida do lado oposto mais elevado (47%), pode estar relacionada com a corrida em curva que sobrecarrega a estrutura da pelve para a manutenção da velocidade com simultânea mudança de direção em função da força gravitacional; iii) a anteversão de pelve (73%) decorre da retração observada nos músculos flexores do quadril e extensores do joelho; iv) a alteração expressa no item iii contribui para a formação de hiperlordose lombar (73%) e desencadeia mecanismo compensatório de retração da cadeia posterior causando cifose torácica (53%) e cabeça em protrusão (73%). O diagnóstico precoce e a adoção de medidas profiláticas efetivas podem contribuir para o aumento da performance, bem como prevenir a ocorrência de lesões desportivas. Estudos envolvendo intervenção fisioterápica deverão avaliar se há redução dos efeitos crônicos que as alterações posturais decorrentes do treinamento causam ao atleta de alto nível.

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CONTEXTO E OBJETIVO: Portadores de insuficiência renal crônica em diálise apresentam alta prevalência de desnutrição proteico-energética. Não existe ainda um método uniforme para avaliar o estado nutricional desses pacientes. Recomenda-se a aplicação de um conjunto de métodos subjetivos e objetivos para se chegar aos diagnósticos nutricionais adequados. O objetivo deste estudo é traçar o perfil nutricional de pacientes submetidos a hemodiálise. TIPO DE ESTUDO E LOCAL: Estudo transversal descritivo realizado na Unidade de Tratamento Dialítico de Araraquara, São Paulo, Brasil, em 2008. MÉTODOS: 48 pacientes tiveram seus indicadores antropométricos e bioquímicos caracterizados, sendo também submetidos ao questionário Avaliação Global Subjetiva modificada (SGAm), verificando-se possíveis correlações entre esses indicadores. RESULTADOS: A frequência de desnutrição moderada e grave variou de 22% a 54%, de acordo com o parâmetro utilizado. Com relação à adequação do peso ideal, 29% da amostra estavam com porcentagem de adequação abaixo do percentil 75, classificados como portadores de desnutrição moderada e grave. As correlações mais significativas foram observadas entre índice de massa corporal (IMC) e adequações de prega triciptal (PCT), circunferência do braço (CB) e circunferência muscular do braço (CMB); e entre o SGAm e adequações de CB e CMB. CONCLUSÃO: A desnutrição apresentou grande variabilidade de frequência entre os pacientes de acordo com o critério escolhido para avaliação. O acompanhamento nutricional de rotina e a validação de métodos que avaliem a composição corporal desses pacientes são de extrema importância para diagnosticar precocemente a desnutrição e assim prevenir complicações e reduzir as taxas de morbimortalidade nesta população.

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In the present work, we have studied the nature of the physical processes of the coronal heating, considering as basis significant samples of single and binary evolved stars, that have been achieved with the ROSAT satellite. In a total of 191 simple stars were studied, classified in the literature as giants with spectral type F, G and K. The results were compared with those obtained from 106 evolved stars of spectral type F, G and K, which belong to the spectroscopic binary systems. Accurate measurements on rotation and information about binarity were obtained from De Medeiros s catalog. We have analysed the behavior of the coronal activity in function of diverse stellar parameters. With the purpose to better clarify the profile of the stars evolution, the HR diagram was built for the two samples of stars, the single and the binary ones. The evolved traces added in the diagram were obtained from the Toulouse-Geneve code, Nascimento et al. (2000). The stars were segregated in this diagram not only in range of rotational speed but also in range of X-ray flux. Our analysis shows clearly that the single stars and the binary ones have coronal activity controlled by physical process independent on the rotation. Non magnetic processes seem to be strongly influencing the coronal heating. For the binary stars, we have also studied the behavior of the coronal emission as a function of orbital parameters, such as period and eccentricity, in which it was revealed the existence of a discontinuity in the emission of X-rays around an orbital period of 100 days. The study helped to conclude that circular orbits of the binary stars are presented as a necessary property for the existence of a higher level ofX-rays emission, suggesting that the effect of the gravitational tide has an important role in the coronal activity level. When applied the Kolmogorov-Smirnov test (KS test ) for the Vsini and FX parameters to the samples of single and binary stars, we could evidence very relevant aspects for the understanding of the mechanisms inherent to the coronal activity. For the Vsini parameter, the differences between the single stars and the binary ones for rotation over 6.3 km/s were really remarkable. We believe, therefore, that the existence of gravitational tide is, at least, one of the factors that most contribute for this behavior. About the X-rays flux, the KS test showed that the behavior of the single and the binary stars, regarding the coronal activity, comes from the same origin

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Important advances have been made along the last decade in the study of the lithium behavior in solar-type stars. Among the most important discoveries what attracts attention is that the distribution of lithium abundance in the late F-type giant stars tends to be discontinuous, at the same time of a sudden decline in rotation and a gradual decline according to the temperature for giant red stars of such spectral type. Other studies have also shown that synchronized binary systems with evolved components seem to keep more of their original lithium than the unsynchronized systems. evertheless, the connection between rotation and lithium abundance as well as the role of tidal effects on lithium dilution seem to be more complicated matters, depending on mass, metallicity and age. This work brings an unprecedented study about the behavior of lithium abundance in solartype evolved stars based on an unique sample of 1067 subgiant, giant and supergiant stars, 236 of them presenting spectroscopic binary characteristics, with precise lithium abundance and projected rotational speed. Now the lithium-rotation connection for single and binary evolved stars is analyzed taking into account the role of mass and stellar age

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Mira and R Coronae Borealis (R CrB) variable stars are evolved objects surrounded by circumstellar envelopes (CSE) composed of the ejected stellar material. We present a detailed high-spatial resolution morfological study of the CSE of three stars: IRC+10216, the closest and more studied Carbon-Rich Mira; o Ceti, the prototype of the Mira class; and RY Sagitarii (RY Sgr), the brightest R CrB variable of the south hemisphere. JHKL near-infrared adaptive optics images of IRC+10216 with high dynamic range and Vband images with high angular resolution and high depth, collected with the VLT/NACO and VLT/FORS1 instruments, were analyzed. NACO images of o Ceti were also analyzed. Interferometric observations of RY Sgr collected with the VLTI/MIDI instrument allowed us to explore its CSE innermost regions (»20 40 mas). The CSE of IRC+10216 exhibit, in near-infrared, clumps with more complex relative displacements than proposed in previous studies. In V-band, the majority of the non-concentric shells, located in the outer CSE layers, seem to be composed of thinner elongated shells. In a global view, the morphological connection between the shells and the bipolar core of the nebulae, located in the outer layers, together with the clumps, located in the innermost regions, has a difficult interpretation. In the CSE of o Ceti, preliminar results would be indicating the presence of possible clumps. In the innermost regions (.110 UA) of the CSE of RY Sgr, two clouds were detected in different epochs, embedded in a variable gaussian envelope. Based on a rigorous verification, the first cloud was located at »100 R¤ (or »30 AU) from the centre, toward the east-north-east direction (modulo 180o) and the second one was almost at a perpendicular direction, having aproximately 2£ the distance of the first cloud. This study introduces new constraints to the mass-loss history of these kind of variables and to the morphology of their innermost CSE regions

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In the first part of this work our concern was to investigate the thermal effects in organic crystals using the theory of the polarons. To analyse such effect, we used the Fröhlich s Hamiltonian, that describes the dynamics of the polarons, using a treatment based on the quantum mechanics, to elucidate the electron-phonon interaction. Many are the forms to analyzing the polaronic phenomenon. However, the measure of the dielectric function can supply important information about the small polarons hopping process. Besides, the dielectric function measures the answer to an applied external electric field, and it is an important tool for the understanding of the many-body effects in the normal state of a polaronic system. We calculate the dielectric function and its dependence on temperature using the Hartree-Fock decoupling method. The dieletric function s dependence on the temperature is depicted by through a 3D graph. We also analyzed the so called Arrhenius resistivity, as a functionof the temperature, which is an important tool to characterize the conductivity of an organic molecule. In the second part we analyzed two perovskita type crystalline oxides, namely the cadmium silicate triclinic (CdSiO3) and the calcium plumbate orthorhombic (CaPbO3), respectively. These materials are normally denominated ABO3 and they have been especially investigated for displaying ferroelectric, piezoelectric, dielectrics, semiconductors and superconductors properties. We found our results through ab initio method within the functional density theory (DFT) in the GGA-PBE and LDA-CAPZ approximations. After the geometry optimization for the two structure using the in two approximations, we found the structure parameters and compared them with the experimental data. We still determined further the angles of connection for the two analyzed cases. Soon after the convergence of the energy, we determined their band structures, fundamental information to characterize the nature of the material, as well as their dielectrics functions, optical absorption, partial density of states and effective masses of electrons and holes

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Conselho Nacional de Desenvolvimento Científico e Tecnológico

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The new technique for automatic search of the order parameters and critical properties is applied to several well-know physical systems, testing the efficiency of such a procedure, in order to apply it for complex systems in general. The automatic-search method is combined with Monte Carlo simulations, which makes use of a given dynamical rule for the time evolution of the system. In the problems inves¬tigated, the Metropolis and Glauber dynamics produced essentially equivalent results. We present a brief introduction to critical phenomena and phase transitions. We describe the automatic-search method and discuss some previous works, where the method has been applied successfully. We apply the method for the ferromagnetic fsing model, computing the critical fron¬tiers and the magnetization exponent (3 for several geometric lattices. We also apply the method for the site-diluted ferromagnetic Ising model on a square lattice, computing its critical frontier, as well as the magnetization exponent f3 and the susceptibility exponent 7. We verify that the universality class of the system remains unchanged when the site dilution is introduced. We study the problem of long-range bond percolation in a diluted linear chain and discuss the non-extensivity questions inherent to long-range-interaction systems. Finally we present our conclusions and possible extensions of this work

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The study of sunspots consistently contributed to a better understanding of magnetic phenomena of the Sun, as its activity. It was found with the dynamics of sunspots that the Sun has a rotation period of twenty-seven days around your axis. With the help of Project Sun-As-A-Star that solar spectra obtained for more than thirty years we observed oscillations of both the depth of the spectral line and its equivalent width, and analysis of the return information about the characteristics of solar magnetism. It also aims to find patterns of solar magnetic activity cycle and the average period of rotation of the Sun will indicate the spectral lines that are sensitive to magnetic activity and which are not. Sensitive lines how Ti II 5381.0 Å stands as the best indicator of the solar rotation period and also shows different periods of rotation cycles of minimum and maximum magnetic activity. It is the first time we observe clearly distinct rotation periods in the different cycles. The analysis also shows that Ca II 8542.1 Å and HI 6562.0 Å indicate the cycle of magnetic activity of eleven years. Some spectral lines no indicated connection with solar activity, this result can help us search for programs planets using spectroscopic models. Data analysis was performed using the Lomb-Scargle method that makes the time series analysis for unequally spaced data. Observe different rotation periods in the cycles of magnetic activity accounts for a discussion has been debated for many decades. We verified that spectroscopy can also specify the period of stellar rotation, thus being able to generalize the method to other stars

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Stellar differential rotation is an important key to understand hydromagnetic stellar dynamos, instabilities, and transport processes in stellar interiors as well as for a better treatment of tides in close binary and star-planet systems. The space-borne high-precision photometry with MOST, CoRoT, and Kepler has provided large and homogeneous datasets. This allows, for the first time, the study of differential rotation statistically robust samples covering almost all stages of stellar evolution. In this sense, we introduce a method to measure a lower limit to the amplitude of surface differential rotation from high-precision evenly sampled photometric time series such as those obtained by space-borne telescopes. It is designed for application to main-sequence late-type stars whose optical flux modulation is dominated by starspots. An autocorrelation of the time series is used to select stars that allow an accurate determination of spot rotation periods. A simple two-spot model is applied together with a Bayesian Information Criterion to preliminarily select intervals of the time series showing evidence of differential rotation with starspots of almost constant area. Finally, the significance of the differential rotation detection and a measurement of its amplitude and uncertainty are obtained by an a posteriori Bayesian analysis based on a Monte Carlo Markov Chain (hereafter MCMC) approach. We apply our method to the Sun and eight other stars for which previous spot modelling has been performed to compare our results with previous ones. The selected stars are of spectral type F, G and K. Among the main results of this work, We find that autocorrelation is a simple method for selecting stars with a coherent rotational signal that is a prerequisite to a successful measurement of differential rotation through spot modelling. For a proper MCMC analysis, it is necessary to take into account the strong correlations among different parameters that exists in spot modelling. For the planethosting star Kepler-30, we derive a lower limit to the relative amplitude of the differential rotation. We confirm that the Sun as a star in the optical passband is not suitable for a measurement of the differential rotation owing to the rapid evolution of its photospheric active regions. In general, our method performs well in comparison with more sophisticated procedures used until now in the study of stellar differential rotation

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The restriction of physical fitness is directly related with hypertension and sleep disorders, while the respiratory muscle strength is associated with hypertension, but the literature is scarce regarding its relationship with sleep disorders and particularly with excessive daytime sleepiness. Objectives: To compare physical fitness and strength of respiratory muscles between people with hypertension with excessive daytime sleepiness (EDS) and non EDS people, those who do not feel excessive daytime sleepiness, in addition to relate aerobics resistance and functional mobility of patients. Methods: An observational, analytical and transversal study, evaluated 32 elderly with hypertension, divided into two groups (EDS and non EDS), in which the following topics were measured; respiratory muscular strength, functional fitness, level of physical activity, level of excessive daytime sleepiness, quality of sleep and intensity of the patients snoring. Results: There was a significant difference in the level of EDS (P=0,00) and quality of sleep (p=0,03), however, the data related to snoring intensity (p=0,18), maximum inspiratory pressure PImax (p=0,39) and maximum expiratory pressure PEmax (p=0,98) did not show any difference. Also, no significant difference was observed concerning physical fitness, presenting p=0,08 for the sitting and getting up test on the chair in 30 ; p=0,54 for the extension and flexing of the elbow test in 30 ; p=0,38 for the walking test 6 ; p=0,38 for the parking gear test 2 , p=0,08 for the sitting and reaching test; p=0,42 for the scratching the back test; p=0,49 for the getting up and walking test; and p=0,62 for the global rate of activity limitation. There was moderate positive correlation between 6MWT and 2MST, r=0,54 (p=0,01) and negative moderate correlation between 6MWT and TUG, r=-0,61 (p=0,000) and between 2MST and TUG, r=-0,60 (p=0,000). Conclusion: The presence of EDS in the hypertension people studied, showed a bad quality of sleep, however this sleepiness did not influence the strength of the respiratory muscles. The physical fitness came out diminished in all hypertension people, regardless of the presence or non presence of sleep disturbance; and there is a close relationship between cardiovascular resistance and physical mobility, since when there is less cardiovascular resistance, there is precarious physical mobility and vice-versa

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Human aging is physiological process causes alterations in several systems of the organism. In the musculoskeletal system, a main change is the decreased muscle strength, that in the lower extremity, compromises the ability to respond quickly with enough strength to prevent falls, causing alterations in postural balance. Currently, many researchers have study the human frailty, defined as a multifactorial syndrome, with excess of vulnerability to stressors, reducing ability in maintaining or regulating homeostasis. Its characteristics are directly related to physical function. Aim: To analyze muscle performance and postural balance in frail and pre-frail elderly women, and to compare them according with the frailty phenotypes criteria proposed by Fried 2001. Method: 39 frail elderly women living in the community, aged 65 years and older, were assessed muscle performance of lower extremity using isokinetic dynamometer and postural balance using Berg s balance scale and computerized baropodometry. Results: There was significant difference in plantar flexor, knee flexor and knee extensor strength, in anteroposterior (AP) oscillation with eyes open and on Berg s scores between groups. A weak correlation was observed between strength and balance. Conclusion: The results suggest that the frail elderly present worse muscle performance in lower extremity and worse postural balance compared to the pre-frail elderly. There were correlations between muscle performance and balance impairments in these elderly, but several variables are also involved in maintaining postural balance

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PURPOSE: To examine the acute effects caused by three techniques for stretching the hamstrings muscle on the active concentric peak torque (PT), passive PT and electromyographic activity (EMG). METHODS: Sixty volunteers (mean ± SD age, 22.6 ± 3 years), height 1.64 ± 0.07m and body weight of 58 ± 8.6kg, were randomly allocated into 4 groups of 15 subjects: Control Group (CG) - 5 minutes at rest, Static Stretching Group (SG) - 2 x 30s; Hold-Relax Group (HRG) - 3 x 6s of isometric contraction of hamstrings interspersed by 10s of hamstrings stretching and agonist Hold-Relax Group (AHRG) - 3 x 6s of isometric contraction of the quadriceps interspersed by 10s of hamstrings stretching. Evaluation has been conducted preand post-intervention, which verified the active concentric PT, passive PT EMG activity of IT. The statistical inference was performed by testing intra and inter, significance level at 5%. RESULTS: After intervention, there was a reduction in passive PT on CG, accompanied by a reduction of EMG activity, and an increase in passive PT on SG and AHRG. There was no change in the active concentric PT, or change in EMG activity. CG showed an increase in angle of the PT active, while the other groups showed no change. CONCLUSION: The results suggest that the shortterm stretching: 1) causes acute increase in passive torque, since the muscle does not perform sub-maximal contraction, 2) does not change in electromyographic activity and active torque, ind ependent of the technique

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Background: The myotonic dystrophy (MD) is a multisystem neuromuscular disease that can affect the respiratory muscles and heart function, and cause impairment in quality of life. Objectives: Investigate the changes in respiratory muscle strength, health-related quality of life (HRQoL) and autonomic modulation heart rate (HR) in patients with MD. Methods: Twenty-three patients performed assessment of pulmonary function, sniff nasal inspiratory pressure (SNIP), the maximal inspiratory (MIP) and expiratory (MEP) pressure, and of HRQoL (SF-36 questionnaire). Of these patients, 17 underwent assessment of heart rate variability (HRV) at rest, in the supine and seated positions. Results: The values of respiratory muscle strength were 64, 70 and 80% of predicted for MEP, MIP, and SNIP, respectively. Significant differences were found in the SF-36 domains of physical functioning (58.7 ± 31,4 vs. 84.5 ± 23, p<0.01) and physical problems (43.4 ± 35.2 vs. 81.2 ± 34, p<0.001) when patients were compared with the reference values. Single linear regression analysis demonstrated that MIP explains 29% of the variance in physical functioning, 18% of physical problems and 20% of vitality. The HRV showed that from supine position to seated, HF decreased (0.43 x 0.30), and LF (0.57 x 0.70) and the LF/HF ratio (1.28 x 2.22) increased (p< 0.05). Compared to healthy persons, LF was lower in both male patients (2.68 x 2.99) and women (2.31 x 2.79) (p< 0.05). LF / HF ratio and LF were higher in men (5.52 x 1.5 and 0.8 x 0.6, p <0.05) and AF in women (0.43 x 0.21) (p< 0.05). There was positive correlation between the time of diagnosis and LF / HF ratio (r = 0.7, p <0.01). Conclusions: The expiratory muscle strength was reduced. The HRQoL was more impaired on the physical aspects and partly influenced by changes in inspiratory muscle strength. The HRV showed that may be sympathetic dysfunction in autonomic modulation of HR, although with normal adjustment of autonomic modulation during the change of posture. The parasympathetic modulation is higher in female patients and sympathetic tends to increase in patients with longer diagnosis

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Background: Down syndrome (DS) is a genetic alteration characterized by being a nonprogressive congenital encephalopathy. Children with DS have hypotonia and developmental delays that interfere in the movement`s acquisition for these children. Objective: Analyze the effects of treadmill inclination on angle and spatiotemporal gait characteristics of these individuals. Methodology: We studied 23 subjects of both sexes, with ages ranged between 05 and 11 years, they presented ability to walk on level 5 classified according to the Functional Ambulation Category (FAC). Initially held a subjective evaluation of balance through a questionnaire (Berg Balance Scale-BBS) then the kinematic gait analysis was realized on a treadmill first, without inclination and then, with inclination of 10%, using the motion system analysis Qualisys System. Data analysis was done using BioStat 5.0 attributing significance level of 5%. Normality of data was verified using D'Agostino test and later was applied paired t-test to compare data in two experimental conditions. Results: There was a statistically significant difference in the spatiotemporal variables: reduction in the cadence (from 108.92 ± 39.07 to 99.11 ± 27.51, p <0.04), increase in cycle time (from 1.24 ± 0.27 to 1.36 ± 0.34, p = 0.03 ) and increase in time to take stock (from 0.77 ± 0.15 to 0.82 ± 0.18, p <0.001). Angular variables that showed statistically significant increasing were: the hip in the initial contact (12.23 ± 4.63 to 18.49 ± 5.17, p <0.0001) and max. flexion in balance (12.96±4:32 to 19.50 ± 4.51, p <0.0001 ), knee in the initial contact (15.59 to ± 6.71 to 21.63 ± 6.48, p <0.0001), the ankle in the initial contact (-2.79 ± 9.8 to 2.25 ± 8.79, p <0.0001), max dorsiflexion in stance (4.41 ± 10.07 to 7.13 ± 11.58, p <0.0009), maximum plantar flexion in the pre-assessment of the ankle joint (increase of -6.33 ± 8.77 to -2.69 ± 8.62, p <0.0004).Conclusions: The inclination acts in a positive way for angular and spatiotemporal features gait of children with Down syndrome, demonstrating possible benefit of using this surface in the gait rehabilitation of children with Down Syndrome