912 resultados para muscular fatigue


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Structural component failures due to cyclic loading are associated to surface damage of materials and its interaction with environment. Fatigue failure occurs with stresses below the yield strength of each material and is a result of crack initiation and propagation. In aeronautical components is an important parameter to be considered in project, as well as the corrosion and wear resistance. Thermally sprayed HVOF coatings have been considered to replace galvanic chromium deposits with comparable performance for wear and corrosion resistance. The aim of present research is to study the influence of WC-13Co-4Cr applied by HVOF, on the axial fatigue strength of 15-5 PH stainless steel. The shot peening treatment was used to restore fatigue performance.

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This project was originated from the national aircraft industry requirements to reduce the use of coated materials with electroplated chromium or cadmium that produce waste, which is harmful to health or the environment. The selected material is a Custom 465 stainless steel used in the aeronautical field due to its high mechanical strength. Considering the load sustained by the wheel axis of the landing gear, the Custom 465 is tested in axial fatigue. The objective is to compare the behavior of the Custom 465 with plated AISI 4340 steel coated with cadmium. X-ray diffraction method was used to determine the residual stress field induced by shot peening.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Introduction: Parkinson’s disease is a chronic disease of the nervous system that leads to a clinical picture of resting tremor, bradykinesia, muscular rigidity and postural instability. These symptoms, in turn, directly influence the functional independence of the individual. Objective: To analyze the influence of muscle strengthening on functional independence of individuals with Parkinson’s disease. Method: A total of ten subjects of both genders participated in this study. We evaluated the functional independence, strength of lower limbs, grip strength testing and 1 repetition maximum. After the evaluation was performed muscle building program for 12 weeks. Results: There was improvement of functional independence (p = 0.007) and lower limb strength (p = 0.01), as well as an increase in grip strength, both of the dominant hand (p = 0.007) and the non-dominant one (p = 0.02). Conclusion: The muscle strength improved the functional independence of individuals with PD.

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Introduction: Some losses resulting from aging can be minimized with the practice of resistive exercises. Objective: To analyze the effects of resistive exercises on flexibility, mobility, muscle strength and balance in the elderly. Method: Twenty elderly individuals were divided between an activity group (AG, n=10; 66.1±6.35 years) and a control group (CG, n=10; 65.4±7.54 years). Mobility, flexibility, muscle strength and balance were evaluated. The AG participated in the training for 13 weeks (one-hour sessions, twice a week). The Wilcoxon non-parametric test (intra-group analysis) was used to analyze the data. A significance level of 5% (p<0.05) was adopted. Results: After training, the AG presented better mobility, lower limb muscle strength, and balance, but no difference in flexibility. Conclusion: The present study allows us to conclude that resistive exercises were able to improve mobility, lower limb muscle strength and balance in elderly individuals.

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The six-minute walking test can be affected by several variables, among them, the respiratory and peripheral muscle strength. The objective of this study was to correlate the respiratory muscle strength (maximum inspiratory pressure – MIP; and maximum expiratory pressure – MEP) and the hand grip test (HGT)with the six minute walking test distance in institutionalized elderly. It was included in this study 9 institutionalized elderly with age over 70 years old, both gender, evaluated by means of manometer, dynamometry and six minute walking test. The data were correlated by using the Pearson’s correlation test and the Spearman correlation test. From the evaluated elderly, it was four men and five women, with mean age: 78.8±7.3 years old, MIP: 75.7±33.6 cmH2O, MEP: 62.4±25.0 cmH2O, HGT: 20.4±6.2 kgf (right member) and 20.7±6.8 kgf (left member) and the distance on six minute walking test: 238.5±99.0 meters. There was correlation between expiratory strength and hand grip of both members with the distance on the six minute walking test. It is possible to conclude that there are correlation between expiratory muscle strength with the hand grip test and the functional capacity in institucionalized elderly.

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The six-minute walking test can be affected by several variables, among them, the respiratory and peripheral muscle strength. The objective of this study was to correlate the respiratory muscle strength (maximum inspiratory pressure – MIP; and maximum expiratory pressure – MEP) and the hand grip test (HGT)with the six minute walking test distance in institutionalized elderly. It was included in this study 9 institutionalized elderly with age over 70 years old, both gender, evaluated by means of manometer, dynamometry and six minute walking test. The data were correlated by using the Pearson’s correlation test and the Spearman correlation test. From the evaluated elderly, it was four men and five women, with mean age: 78.8±7.3 years old, MIP: 75.7±33.6 cmH2O, MEP: 62.4±25.0 cmH2O, HGT: 20.4±6.2 kgf (right member) and 20.7±6.8 kgf (left member) and the distance on six minute walking test: 238.5±99.0 meters. There was correlation between expiratory strength and hand grip of both members with the distance on the six minute walking test. It is possible to conclude that there are correlation between expiratory muscle strength with the hand grip test and the functional capacity in institucionalized elderly.

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Uma das técnicas mais modernas utilizada na fisioterapia e em outras áreas da saúde é o método Pilates. Esse método utiliza de forma intensa a respiração, e pode assim alterar a força muscular respiratória. O objetivo do presente estudo é verificar se há influência da prática do Método Pilates na força muscular respiratória em adultos e comparar com um grupo controle. Foram selecionados 20 indivíduos, divididos em dois grupos (controle e experimental), com idades de 20 a 30 anos, não fumantes, sedentários e que relatem não apresentar qualquer doença sistêmica ou metabólica. Todos os indivíduos foram submetidos à avaliação da pressão inspiratória máxima (Pimáx) e pressão expiratória máxima (Pemáx) com aparelho manovacuômetro (Comercial Médica). A seguir, foi aplicado um protocolo de 10 sessões de pilates para o grupo experimental, constituído dos seguintes exercícios do método: Spine stretch, Spine stretch forward, Saw, Mermaid, Swan, Breast stroke preparation, Abdominal curls, Roll up, Bridge, Single leg circles, Leg up and down, The hundred, Criss cross, Single leg stretch, Double leg stretch, Aductors, Shell. O grupo controle permaneceu sem atividade física. Após cinco semanas os dois grupos foram reavaliados. Os resultados encontrados demonstraram um incremento na força muscular respiratória do grupo experimental. Após a aplicação do teste Anova (p<0,05) foi encontrada diferença estatisticamente significante somente na comparação da Pimax inicial e final do grupo experimental (p = 0,028).

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Statement of problem. Removable partial dentures are affected by fatigue because of the cyclic mechanism of the masticatory system ansi frequent insertion and removal. Titanium and its alloys have been used in the manufacture of denture frameworks; however, preventive agents with fluorides are thought to attack titanium alloy surfaces.Purpose. This study evaluated, compared, analyzed the corrosion-fatigue life of commercially pure titanium and Ti-6Al-4V alloy in different storage environments.Material and methods. For each metal, 33 dumbbell rods, 2.3 mm in diameter at the central segment, were cast in the Rematitan system. Corrosion-fatigue strength test was carried out through a universal testing machine with a load 30% lon er than the 0.2% offset yield strength and a combined influence of different: environments: in air at room temperature, with synthetic saliva, and with fluoride synthetic saliva. After failure, the number of cycles were recorded, and fracture surfaces were examined with on SEM.Results. ANOVA and Tukey's multiple comparison rest indicated that Ti-6Al-4V alloy achieved 21,269 cycles (SD = 8,355) against 19,157 cycles (SD = 3,624) for the commercially purr Ti. There were no significant differences between either metal in the corrosion-fatigue life for dry specimens, but when the solutions were present, the fatigue life was significantly reduced, probably because of the product-ion of corrosion pits caused by superficial reactions.