931 resultados para muscular strength


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Several methods are used towards delayed onset muscle soreness appraisal. This study's goal was to investigate, amongst three commonly adopted methods, which one would be the most effective (the one that shows higher values) in the quantification of this phenomenon. 10 male subjects, of age 22.8 ± 3.1 years old, weight 80 ± 12.4 kg, height 174 ± 0.07 cm, without recent experience with strength training (lower limbs) and/or running took place in this study. All subjects carried out a muscle damage induction protocol, which consisted of 30 minute downhill running (-16% or -9.09º) at 80% speed compared to their maximum oxygen consumption. Muscle damage determinants such as isometric peak torque, knee joint range of motion and circumference of the medial portion of the thight were measured before, during, 24, 48, 72 and 96 hours after downhill running. The subjective pain perception was measured simultaneously with the other determinants through three different tests: sitting on and getting up of a chair; climbing and descending from a 45cm step; and self thigh palpation. After going through all subjective pain perception tests, the subjects filled out a visual analog scale with their perception of pain. Muscle damage changes over time were compared through variance analysis (ANOVA) one way for repeated measures. Subjective pain perception values obtained in all three different tests were compared through two way ANOVAs for repeated numbers. The significance level adopted in this study was z ≤ 0.05. The results showed that the step test was the on which better evaluated the delayed onset muscle soreness. No significant differences were found through the ADM and CIR recovery markers. Downhil running determined reduced of PTI (~22.4%). Significant links between pain were obtained for both subjective pain perception tests starting at 24 and 48 hours, where the highest registered average happened in the step test after 48h, with high...

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The use of rats in studies that seek to monitor the effects of physical exercise is fairly common, even in works that make use of overload. However, the correct determination of the training load is critical to success of studies. Thus, with the objective of verifying the correlation of total body mass of the rats with their respective strength, and the correlation of the 1RM test with test repetitions, 40 rats, 90 days old and weighing average 0,49 pounds underwent a program of adaptation to the water and then were subjected to tests to determine the maximal and submaximal loads. After measuring the total body mass and maximal and submaximal strenght, it was possible to observe directly proportional relationship between maximum strenght and total body mass of 0.97 (P ≤ 0.01), being the maximum muscle strength equivalent to 109% of the total body mass. Between muscle strength and mass submaximal muscle strength was also found direct correlation between the variables, allowing to conclude that the submaximal strength test and total body mass are effective tools in determining the training load of rats.

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

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

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Pós-graduação em Desenvolvimento Humano e Tecnologias - IBRC

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Pós-graduação em Desenvolvimento Humano e Tecnologias - IBRC

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Background and Study Aim: The grip strength endurance is important for Brazilian Jiu-Jitsu (BJJ). Thus, the aims of this study were: a) to test the reliability of two kimono grip strength tests named maximum static lift (MSL) and maximum number of repetitions (MNR) and b) to examine differences between elite and non-elite BJJ players in these tests. Material/Methods: Thirty BJJ players participated into two phases: "A" to test reliability and "B" to compare elite and non-elite. In phase A, twenty participants performed the MSL and, 15 min later, the MNR in two occasions with 24-h interval. In phase B, ten other BJJ practitioners (non-elite) and ten athletes (elite) performed the same tests. The intraclass correlation coefficient (ICC) two way fixed model (3,1), Bland-Altman plot and the limits of agreement were used to test reliability, correlation between the tests were evaluated by Pearson correlations and independent T test (P<0.05) was utilized to compare elite vs. non-elite. Results: The ICC was high for repeated measurements on different days of phase A (MSL: r=0.99 and MNR: r=0.97). Limits of agreement for time of suspension were -6.9 to 2.4-s, with a mean difference of -2.3 s (CI: -3.3 to -1.2-s), while for number of repetitions the limits of agreement were -2.9 to 2.3-rep, with a mean difference of -0.3-rep (CI: -0.9 to 0.3-rep). In phase B, elite presented better performance for both tests (P<0.05) compared to non-elite (56 +/- 10-s vs. 37 +/- 11-s in MSL and 15 +/- 4-rep vs. 8 +/- 3-rep in MNR). Moderate correlation were found between MSL and MNR for absolute values during test (r=0.475; p=0.034), and retest phases (r=0.489; p=0.029), while moderate and high correlations in the test (r=0.615; p=0.004) and retest phases (r=0.716; p=0.001) were found for relative values, respectively. Conclusions: These proposed tests are reliable and both static and dynamic grip strength endurance tests seem to differentiate BJJ athletes from different levels.

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Objective: To assess the evolution of motor function in patients with Duchenne muscular dystrophy (DMD) treated with steroids (prednisolone or deflazacort) through the Motor Function Measure (MFM), which evaluates three dimensions of motor performance (D1, D2, D3). Methods: Thirty-three patients with DMD (22 ambulant, 6 non-ambulant and 5 who lost the capacity to walk during the period of the study) were assessed using the MFM scale six times over a period of 18 months. Results: All the motor functions remained stable for 14 months in all patients, except D1 for those who lost their walking ability. In ambulant patients, D2 (axial and proximal motor capacities) motor functions improved during six months; an improvement in D3 (distal motor capacity) was noted during the total follow-up. D1 (standing posture and transfers) and total score were useful to predict the loss of the ability to walk. Conclusions: The use of the MFM in DMD patients confirms the benefits of the steroid treatment for slowing the progression of the disease.

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Background Duchenne muscular dystrophy (DMD) is a sex-linked inherited muscle disease characterized by a progressive loss in muscle strength and respiratory muscle involvement. After 12 years of age, lung function declines at a rate of 6 % to 10.7 % per year in patients with DMD. Steroid therapy has been proposed to delay the loss of motor function and also the respiratory involvement. Method In 21 patients with DMD aged between seven and 16 years, the forced vital capacity (FVC) and the forced expiratory volume in one second (FEV1) were evaluated at three different times during a period of two years. Results We observed in this period of evaluation the maintenance of the FVC and the FEV1 in this group of patients independently of chronological age, age at onset of steroid therapy, and walking capacity. Conclusion The steroid therapy has the potential to stabilize or delay the loss of lung function in DMD patients even if they are non-ambulant or older than 10 years, and in those in whom the medication was started after 7 years of age.

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OBJETIVOS: Comparar os parâmetros metabólicos, a composição corporal e a força muscular de mulheres com Síndrome dos Ovários Policísticos (SOP) em relação a mulheres com ciclos menstruais ovulatórios. MÉTODOS: Estudo caso-controle com 27 mulheres com SOP e 28 mulheres controles com ciclos ovulatórios, com idade entre 18 e 37 anos, índice de massa corpórea entre 18 e 39,9 kg/m², que não praticassem atividade física regular. Níveis séricos de testosterona, androstenediona, prolactina, globulina carreadora dos hormônios sexuais (SHBG), insulina e glicemia foram avaliados. Índice de andrógeno livre (FAI) e resistência insulina (por HOMA) foram calculados. As voluntárias submetidas avaliação de composição corporal por dobras cutâneas e absorciometria de raio X de dupla energia (DEXA) e testes de força muscular máxima de 1-RM em três exercícios após procedimento de familiarização e de força isométrica de preensão manual. RESULTADOS: Os níveis de testosterona foram mais elevados no grupo SOP em relação ao CO (68,0±20,2 versus 58,2±12,8 ng/dL; p=0,02), assim como o FAI (282,5±223,8 versus 127,0±77,2; p=0,01), a insulina (8,4±7,0 versus 4,0±2,7 uIU/mL; p=0,01), e o HOMA (2,3±2,3 versus1,0±0,8; p=0,01). O SBHG foi inferior no grupo SOP comparado ao controle (52,5±43,3 versus 65,1±27,4 nmol/L; p=0,04). Não foram observadas diferenças significativas na composição corporal com os métodos propostos entre os grupos. O grupo SOP apresentou maior força muscular no teste de 1-RM nos exercícios supino reto (31,2±4,75 versus 27,8±3,6 kg; p=0,04) e cadeira extensora (27,9±6,2 versus 23,4±4,2 kg; p=0,01), assim como nos testes de força isométrica de preensão manual (5079,6±1035,7 versus 4477,3±69,6 kgf/m²; p=0,04). Ser portadora de SOP foi um preditor independente de aumento de força muscular nos exercícios supino reto (estimativa (E)=2,7) (p=0,04) e cadeira extensora (E=3,5) (p=0,04). Assim como o IMC no exercício de força isométrica de preensão manual do membro dominante (E=72,2) (p<0,01), supino reto (E=0,2) (p=0,02) e rosca direta (E=0,3) (p<0,01). Nenhuma associação foi encontrada entre HOMA-IR e força muscular. CONCLUSÕES: Mulheres com SOP apresentam maior força muscular, sem diferença na composição corporal. A RI não esteve associada ao desempenho da força muscular. Possivelmente, a força muscular pode estar relacionada aos níveis elevados de androgênios nessas mulheres.

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Um dos maiores problemas de saúde pública na população idosa são as quedas, agravando-se quando relacionadas à presença de osteoporose. Dentre os vários fatores de risco, destacam-se a diminuição do equilíbrio, controle postural e força muscular. O objetivo deste trabalho foi comparar o equilíbrio, o controle postural e a força muscular em idosas osteoporóticas com e sem quedas referidas no último ano. Foram avaliadas 45 mulheres entre 65 e 85 anos, divididas em dois grupos com base no relato de quedas nos 12 meses anteriores à avaliação: grupo com quedas (GCQ; n=21) e grupo sem quedas (GSQ; n=24). O equilíbrio foi avaliado por meio da escala de equilíbrio de Berg; o controle postural pelo teste clínico modificado de interação sensorial no equilíbrio (mCTSIB), realizado no equipamento Balance Master®; e a força muscular dos flexores e extensores de joelho e dorsiflexores de tornozelo, com dinamômetro EMG System do Brasil®. Foi considerado nível de significância α=0,05. Houve diferença significativa no equilíbrio (p<0,01) e na velocidade de oscilação do Centro de Pressão (CP) durante o teste mCTSIB nas condições olhos fechados superfície estável (p=0,05) e olhos abertos superfície instável (p<0,01), com valores maiores para o GCQ. Os grupos foram semelhantes entre si em relação à força muscular (p>0,05). Nossos resultados indicam que idosas osteoporóticas com histórico de quedas nos últimos 12 meses possuem pior equilíbrio e controle postural em relação às osteoporóticas sem quedas referidas.

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Reprogramming of gene expression contributes to structural and functional adaptation of muscle tissue in response to altered use. The aim of this study was to investigate mechanisms for observed improvements in leg extension strength, gain in relative thigh muscle mass and loss of body and thigh fat content in response to eccentric and conventional strength training in elderly men (n = 14) and women (n = 14; average age of the men and women: 80.1 ± 3.7 years) by means of structural and molecular analyses. Biopsies were collected from m. vastus lateralis in the resting state before and after 12 weeks of training with two weekly resistance exercise sessions (RET) or eccentric ergometer sessions (EET). Gene expression was analyzed using custom-designed low-density PCR arrays. Muscle ultrastructure was evaluated using EM morphometry. Gain in thigh muscle mass was paralleled by an increase in muscle fiber cross-sectional area (hypertrophy) with RET but not with EET, where muscle growth is likely occurring by the addition of sarcomeres in series or by hyperplasia. The expression of transcripts encoding factors involved in muscle growth, repair and remodeling (e.g., IGF-1, HGF, MYOG, MYH3) was increased to a larger extent after EET than RET. MicroRNA 1 expression was decreased independent of the training modality, and was paralleled by an increased expression of IGF-1 representing a potential target. IGF-1 is a potent promoter of muscle growth, and its regulation by microRNA 1 may have contributed to the gain of muscle mass observed in our subjects. EET depressed genes encoding mitochondrial and metabolic transcripts. The changes of several metabolic and mitochondrial transcripts correlated significantly with changes in mitochondrial volume density. Intramyocellular lipid content was decreased after EET concomitantly with total body fat. Changes in intramyocellular lipid content correlated with changes in body fat content with both RET and EET. In the elderly, RET and EET lead to distinct molecular and structural adaptations which might contribute to the observed small quantitative differences in functional tests and body composition parameters. EET seems to be particularly convenient for the elderly with regard to improvements in body composition and strength but at the expense of reducing muscular oxidative capacity.

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La termografía infrarroja (TI) es una técnica no invasiva y de bajo coste que permite, con el simple acto de tomar una fotografía, el registro sin contacto de la energía que irradia el cuerpo humano (Akimov & Son’kin, 2011, Merla et al., 2005, Ng et al., 2009, Costello et al., 2012, Hildebrandt et al., 2010). Esta técnica comenzó a utilizarse en el ámbito médico en los años 60, pero debido a los malos resultados como herramienta diagnóstica y la falta de protocolos estandarizados (Head & Elliot, 2002), ésta se dejó de utilizar en detrimento de otras técnicas más precisas a nivel diagnóstico. No obstante, las mejoras tecnológicas de la TI en los últimos años han hecho posible un resurgimiento de la misma (Jiang et al., 2005, Vainer et al., 2005, Cheng et al., 2009, Spalding et al., 2011, Skala et al., 2012), abriendo el camino a nuevas aplicaciones no sólo centradas en el uso diagnóstico. Entre las nuevas aplicaciones, destacamos las que se desarrollan en el ámbito de la actividad física y el deporte, donde recientemente se ha demostrado que los nuevos avances con imágenes de alta resolución pueden proporcionar información muy interesante sobre el complejo sistema de termorregulación humana (Hildebrandt et al., 2010). Entre las nuevas aplicaciones destacan: la cuantificación de la asimilación de la carga de trabajo físico (Čoh & Širok, 2007), la valoración de la condición física (Chudecka et al., 2010, 2012, Akimov et al., 2009, 2011, Merla et al., 2010), la prevención y seguimiento de lesiones (Hildebrandt et al., 2010, 2012, Badža et al., 2012, Gómez Carmona, 2012) e incluso la detección de agujetas (Al-Nakhli et al., 2012). Bajo estas circunstancias, se acusa cada vez más la necesidad de ampliar el conocimiento sobre los factores que influyen en la aplicación de la TI en los seres humanos, así como la descripción de la respuesta de la temperatura de la piel (TP) en condiciones normales, y bajo la influencia de los diferentes tipos de ejercicio. Por consiguiente, este estudio presenta en una primera parte una revisión bibliográfica sobre los factores que afectan al uso de la TI en los seres humanos y una propuesta de clasificación de los mismos. Hemos analizado la fiabilidad del software Termotracker, así como su reproducibilidad de la temperatura de la piel en sujetos jóvenes, sanos y con normopeso. Finalmente, se analizó la respuesta térmica de la piel antes de un entrenamiento de resistencia, velocidad y fuerza, inmediatamente después y durante un período de recuperación de 8 horas. En cuanto a la revisión bibliográfica, hemos propuesto una clasificación para organizar los factores en tres grupos principales: los factores ambientales, individuales y técnicos. El análisis y descripción de estas influencias deben representar la base de nuevas investigaciones con el fin de utilizar la TI en las mejores condiciones. En cuanto a la reproducibilidad, los resultados mostraron valores excelentes para imágenes consecutivas, aunque la reproducibilidad de la TP disminuyó ligeramente con imágenes separadas por 24 horas, sobre todo en las zonas con valores más fríos (es decir, zonas distales y articulaciones). Las asimetrías térmicas (que normalmente se utilizan para seguir la evolución de zonas sobrecargadas o lesionadas) también mostraron excelentes resultados pero, en este caso, con mejores valores para las articulaciones y el zonas centrales (es decir, rodillas, tobillos, dorsales y pectorales) que las Zonas de Interés (ZDI) con valores medios más calientes (como los muslos e isquiotibiales). Los resultados de fiabilidad del software Termotracker fueron excelentes en todas las condiciones y parámetros. En el caso del estudio sobre los efectos de los entrenamientos de la velocidad resistencia y fuerza en la TP, los resultados muestran respuestas específicas según el tipo de entrenamiento, zona de interés, el momento de la evaluación y la función de las zonas analizadas. Los resultados mostraron que la mayoría de las ZDI musculares se mantuvieron significativamente más calientes 8 horas después del entrenamiento, lo que indica que el efecto del ejercicio sobre la TP perdura por lo menos 8 horas en la mayoría de zonas analizadas. La TI podría ser útil para cuantificar la asimilación y recuperación física después de una carga física de trabajo. Estos resultados podrían ser muy útiles para entender mejor el complejo sistema de termorregulación humano, y por lo tanto, para utilizar la TI de una manera más objetiva, precisa y profesional con visos a mejorar las nuevas aplicaciones termográficas en el sector de la actividad física y el deporte Infrared Thermography (IRT) is a safe, non-invasive and low-cost technique that allows the rapid and non-contact recording of the irradiated energy released from the body (Akimov & Son’kin, 2011; Merla et al., 2005; Ng et al., 2009; Costello et al., 2012; Hildebrandt et al., 2010). It has been used since the early 1960’s, but due to poor results as diagnostic tool and a lack of methodological standards and quality assurance (Head et al., 2002), it was rejected from the medical field. Nevertheless, the technological improvements of IRT in the last years have made possible a resurgence of this technique (Jiang et al., 2005; Vainer et al., 2005; Cheng et al., 2009; Spalding et al., 2011; Skala et al., 2012), paving the way to new applications not only focused on the diagnose usages. Among the new applications, we highlighted those in physical activity and sport fields, where it has been recently proven that a high resolution thermal images can provide us with interesting information about the complex thermoregulation system of the body (Hildebrandt et al., 2010), information than can be used as: training workload quantification (Čoh & Širok, 2007), fitness and performance conditions (Chudecka et al., 2010, 2012; Akimov et al., 2009, 2011; Merla et al., 2010; Arfaoui et al., 2012), prevention and monitoring of injuries (Hildebrandt et al., 2010, 2012; Badža et al., 2012, Gómez Carmona, 2012) and even detection of Delayed Onset Muscle Soreness – DOMS- (Al-Nakhli et al., 2012). Under this context, there is a relevant necessity to broaden the knowledge about factors influencing the application of IRT on humans, and to better explore and describe the thermal response of Skin Temperature (Tsk) in normal conditions, and under the influence of different types of exercise. Consequently, this study presents a literature review about factors affecting the application of IRT on human beings and a classification proposal about them. We analysed the reliability of the software Termotracker®, and also its reproducibility of Tsk on young, healthy and normal weight subjects. Finally, we examined the Tsk thermal response before an endurance, speed and strength training, immediately after and during an 8-hour recovery period. Concerning the literature review, we proposed a classification to organise the factors into three main groups: environmental, individual and technical factors. Thus, better exploring and describing these influence factors should represent the basis of further investigations in order to use IRT in the best and optimal conditions to improve its accuracy and results. Regarding the reproducibility results, the outcomes showed excellent values for consecutive images, but the reproducibility of Tsk slightly decreased with time, above all in the colder Regions of Interest (ROI) (i.e. distal and joint areas). The side-to-side differences (ΔT) (normally used to follow the evolution of some injured or overloaded ROI) also showed highly accurate results, but in this case with better values for joints and central ROI (i.e. Knee, Ankles, Dorsal and Pectoral) than the hottest muscle ROI (as Thigh or Hamstrings). The reliability results of the IRT software Termotracker® were excellent in all conditions and parameters. In the part of the study about the effects on Tsk of aerobic, speed and strength training, the results of Tsk demonstrated specific responses depending on the type of training, ROI, moment of the assessment and the function of the considered ROI. The results showed that most of muscular ROI maintained warmer significant Tsk 8 hours after the training, indicating that the effect of exercise on Tsk last at least 8 hours in most of ROI, as well as IRT could help to quantify the recovery status of the athlete as workload assimilation indicator. Those results could be very useful to better understand the complex skin thermoregulation behaviour, and therefore, to use IRT in a more objective, accurate and professional way to improve the new IRT applications for the physical activity and sport sector.