How does static stretching influence the tendons mechanical response?

OBJECTIVE: Analyze in vitro the mechanical response of bovine calcaneus tendons subjected to static stretching in three different intervals (15, 30, 45 s). METHODS: Six groups of bovine calcaneus tendons (n=10) were formed according to the static stretching protocol: three different intervals (15, 30, 45 s) and initial stretching percentage (2.5% and 3.5%). The control group (n=10) did not perform prior stretching. At the end of the stretching tests, the specimens were subjected to stress rupture tests. RESULTS: The values for force relaxation presented stability after the 30th second (p<0.0001) at both levels of deformation. Greater force relaxation (p<0.0026) and the least tensile strength (p=0.0123) was observed in the group that was subjected to the highest stretch percentage (3.5%). No difference was observed between the rupture parameters of the stretch and control groups. The variables, stretch duration and percentage did not demonstrate interaction. CONCLUSION: In relation to force relaxation, the 30 second interval seems to be the most effective when stretching tendons. This fact should be considered when establishing new clinical stretching protocols. Laboratory investigation.OBJETIVO: Analisar in vitro, a resposta mecânica de tendões calcâneo bovino, submetidos ao alongamento estático e avaliar a influência do alongamento no evento lesivo. MÉTODOS: Seis grupos de espécimes de tendões calcâneos bovinos (n=10) foram submetidos a alongamento estático: três intervalos (15, 30, 45 segundos) e percentuais de alongamento inicial (2,5 e 3,5%). O grupo controle (n=10) não realizou alongamento prévio. Ao termino do ensaio de alongamento, os espécimes foram submetidos ao ensaio de ruptura. RESULTADOS: Os valores de relaxamento de força apresentaram estabilização a partir do trigésimo segundo (p<0.0001) nos dois níveis de deformação estudados. Foi observado maior relaxamento de força (p<0.0026) e menor tensão de ruptura (p = 0.0123) para o grupo submetido a maior taxa de alongamento percentual (3,5%). Não houve diferença nos parâmetros de ruptura entre os grupos alongamento e controle. As variáveis tempo e percentual de alongamento não apresentaram interação. CONCLUSÃO: Considerando-se o relaxamento de estresse, o intervalo de 30 segundos parece ser o mais efetivo no alongamento de tendões, fato a ser considerado no estabelecimento de novos protocolos clínicos de alongamento. Trabalho experimental.25826

Análise ótica da parede abdominal pelo biospeckle após implante de prótese de polipropileno em ratos

To evaluate an experimental animal model to study the abdominal tissue activity considering its interaction with a polypropylene mesh, through the use of one of the optical phenomena of light Laser, the biospeckle. Fifty Wistar male rats were divided into four groups: Group 1: ten animals not submitted to surgery; Group 2: ten animals submitted to surgery without polypropylene mesh; Group 3: 20 animals submitted to surgery followed by the mesh placement; Group 4: (sham) with ten animals. None of the animals presented post surgical complications being submitted to the optical tests at the 20th postoperative day. The analysis from the biospeckle tests, comparing the medians and standard deviations with T Student test, indicated that no significative difference was observed on the abdominal wall tissue activity in the four groups considered, with and without polypropylene mesh prosthesis implantation. The animal model is viable and the biospeckle open ways for a great number of experiments to be developed in evaluating tissue activity246442448Avaliar o modelo experimental animal para o estudo da atividade tecidual da parede abdominal em sua interação com a prótese de polipropileno, através da utilização de um dos fenômenos ópticos da luz Laser, o biospeckle. Foram utilizados 50 ratos Wistar machos, divididos em quatro grupos: Grupo 1 com 10 animais não operados e controles; Grupo 2 com 10 animais submetidos a cirurgia sem a colocação de prótese; Grupo 3 com 20 animais submetidos a cirurgia com colocação de prótese de polipropileno pré-peritonial; Grupo 4 (Sham) com 10 animais. Nenhum animal apresentou complicações pós-operatórias, sendo que no 20º PO foram submetidos ao ensaio óptico. A comparação das médias e o desvio padrão das medidas da atividade tecidual da parede abdominal, com e sem implantação da prótese de polipropileno obtidas dos grupos de animais, pelo teste T de Student, não evidenciou diferença estatística significativa (p>0.05). A análise dos dados obtidos permitiu concluir que o modelo animal é viável e que o biospeckle abre caminhos para toda uma linha de experimentos a ser desenvolvida em avaliar atividade tecidua

Estudo da perda da tensao do enxerto de tendão calcâneo bovino

A lesão do ligamento cruzado anterior do joelho (LCA) é um problema que afeta tanto os animais como os seres humanos, e pode evoluir com instabilidade articular, muitas vezes, sintomática e incapacitante para o paciente. Os enxertos de tendões autólogos são a principal opção como substitutos ligamentares. Durante a reconstrução cirúrgica do LCA, o enxerto é submetido a tensionamento com o objetivo de restabelecer a lassidão normal do joelho LCA-deficiente. Embora o tensionamento do enxerto exerça papel fundamental na evolução clínica pós-operatória, a literatura ainda não estabeleceu os níveis ideais de tensionamento a serem aplicados. Assim, o estiramento ou elongamento do enxerto que pode ocorrer com o passar do tempo permanece como uma das principais causas da falha da reconstrução ligamentar.Neste trabalho, dez tendões de calcâneo bovino foram submetidos a dois ensaios sucessivos de tensionamento fisiológico a deformação relativa máxima de 2.5% do comprimento inicial do tendão ensaiado, mantida durante 600s, sendo registrados os valores de força (N) no tempo zero (inicial), 300s e 600s. Ao término do primeiro ensaio, o tendão retornava ao seu comprimento inicial, sendo mantido em repouso durante 300s, seguido de novo ensaio de tensionamento repetindo-se os mesmos procedimentos anteriores. A análise estatística permitiu concluir que o elongamento do tendão é mais pronunciado nos 300s iniciais, refletindo uma queda mais acentuada nos valores da tensão do enxerto. Portanto, 300s após o tensionamento e fixação do enxerto, o cirurgião pode avaliar mais adequadamente se o nível de tensionamento foi suficiente.Lesion of the anterior cruciate ligament (ACL) in the knee is a problem that affects animals as well as humans and may evolve with joint instability that is often symptomatic and incapacitating. The main option for ligament substitution is the autologous tendon graft. The graft undergoes tensioning during ACL reconstructive surgery to reestablish the normal laxity of the ACL- deficient knee. Although graft tensioning plays a fundamental role in postoperative clinical evolution, ideal tensioning levels have not been established in the literature. Therefore, graft elongation that may occur over time is still one of the main reasons for ligament reconstruction failure. In this study, ten bovine calcaneus tendons underwent two successive assays of physiological tensioning for a maximum deformation of 2.5% of the initial tendon length, maintained for 600s with force (N) values recorded at zero time (initial), 300s and 600s. At the end of the first assay, the tendon returned to its initial length and was maintained at rest for 300s and then the next tensioning assay was initiated, repeating the previous procedure. Statistical analysis revealed that tendon elongation is more pronounced during the initial 300s, reflecting a more accentuated decline in the tension values of the graft. Therefore, 300s after tensioning and fixing the graft, the surgeon can assess with more precision if the tensioning level was adequate

Three-dimensional reconstruction of live fish through the moiré technique

Currently, in fish farms, the controls of the physical characteristics of the fishes, for example, size and mass are made by means of the operation of fish removal, in which the tanks are emptied to capture the animals and perform the biometry. This operation demands large volumes of water and generates effluent containing high concentrations of organic matter and nutrients that can contribute to the deterioration of water quality in the recipient bodies. Therefore, the development of technologies that use digital image processing, such as the moiré technique and image analysis, can be important allies for the preservation of environmental quality by avoiding the fish removal and the discharge of effluents, increasing productivity due to optimization of the time and still the saving of water. To obtain the images a 9-liter glass aquarium, a support for notebook and light projector, a digital camera brand Samsung Galaxy Camera 2 were used. The objective of this work was to obtain the three-dimensional reconstruction of live fish in aquariums. In the future, the technique can be developed to obtain the mass and the volume of the fish in fish tanks, replacing the fish removal, allowing the preservation of water resources.824224

Técnica de Moiré aplicada al análisis de esfuerzos de compresión en el bambú Guadua

El bambú es considerado como una materia prima muy importante para los países en vías de desarrollo, pues combina levedad con una elevada resistencia mecánica. Hasta ahora no se conoce adecuadamente el comportamiento del material cuando es sometido a los ensayos de caracterización mecánica. En este trabajo se buscó evaluar probetas de bambú (Guadua angustifolia) sometidas al ensayo de compresión simple. Se utilizó la técnica de moiré de sombra para mapear las deformaciones de las probetas en función de la cantidad de nudos presentes en ella (0, 1 ó 2). Los resultados obtenidos evidenciaron la adecuación de la técnica utilizada, permitiendo observar la distribución de las líneas de iso-deformación en el bambú. AbstractBamboo is considered an important raw material in developing countries because its physical characteristics associate lightness with high mechanical resistance. However its behavior obtained from mechanical tests is not yet well defined. This research work had the objective of evaluating bamboo (Guadua angustifolia) testing specimens under simple uniaxial compression loading. Shadow moiré optical methods had been employed to generate deformation mapping as function of knots (0, 1 or 2). Obtained results indicate that the technique is well adequate in generating iso-deformation contour lines in bamboo specimens

MOIRÉ OPTICAL TECHNIQUE FOR EVALUATION OF CASHEW NUTS (Anacardium Occidentale, L.) ISOSTRAIN

A figure corresponding to 96% of the Brazilian production of cashew nuts is forwared to industrial processing yielding only 50 to 60% of whole kernels. An appropriated knowledge of nut mechanical behavior would be important to support the development of equipment designed to minimize losses during processing.&nbsp; The nut shell is composed of three layers identified as the epicarp, mesocarp and endocarp, which exhibit distinct behavior beyond mechanical excitations. An important class of mechanical loading is recognized to be the contact stress which is generated from the pressure exerted among two elastic bodies in contact. However the structural as well as the geometrical complexity of the nut deserves a suitable methodology to investigate stress distribution in cashew nuts. Shadow moir&eacute; technique was identified to support a suitable stress analysis method for the present case. Ten individuals were submitted to the trials, being 05 scarified nuts and 05 non scarified. A conventional optical setup was prepared to support a shadow moir&eacute; test. It was observed close correlation between external and internal load distribution. The technique was showed to be efficient to obtain a qualitative correlation of deformation distribution in the endocarp, as well as in the epicarp

Graft semitendinosus and gracilis human muscle tendons elongation: a study carried out on young adult human cadavers

Na cirurgia de reconstrução do ligamento cruzado anterior do joelho, os enxertos de tendões autólogos são a principal opção como substitutos ligamentares. Entretanto, uma das razões da falha da reconstrução ligamentar com tecidos moles é o estiramento ou elongamento do enxerto com o tempo. Neste trabalho, foram ensaiados oito tendões do músculo grácil e oito do músculo semitendinoso humanos, obtidos de quatro cadáveres do sexo masculino, com idade média de 24,5 anos. Cada tendão foi submetido a uma deformação relativa constante de 2,5% durante 600 s, com registro contínuo do relaxamento de força. A seguir, o tendão retornava ao seu comprimento inicial e era mantido num período de repouso de 300 s. Após este intervalo, um segundo ensaio, semelhante ao primeiro, era realizado. A velocidade de carregamento empregada foi de 10% do comprimento inicial do corpo de prova por segundo. Foram obtidos valores de força inicial, com 300 s e 600 s nos dois ensaios. A análise estatística sugere um comportamento mecânico mais uniforme para o tendão do músculo semitendinoso quando comparado ao tendão do músculo grácil.In the anterior cruciate ligament knee surgery reconstruction, autologous tendons graft remains as a main option as substitutive ligaments. However time effect on graft elongation is the main reason of ligament reconstruction failure. Traction tests have been performed on eight gracilis as well as on eight semitendinosus human muscles tendons obtained from four male cadavers at an average of 24.5 years. Each tendon specimen has been submitted to a deformation of 2.5% of its initial length for a time interval of 600 s with continuous recording of the corresponding force relaxation. The tendon specimen was then kept at rest for 300 s as soon as it returned to its initial length. The same specimen was then submitted to a similar test. Deformation rate for both tests was 10% of its initial length per second. Initial force values were obtained for resting time interval of 300 s as well as for 600 s. Statistical analysis suggests that the semitendinosus muscle tendon exhibits a more uniform mechanical behavior, as compared to gracilis muscle