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Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-05T12:45:29Z No. of bitstreams: 2 jorge_augusto_barroso.pdf: 605983 bytes, checksum: 4317652388abdb60186382b0434386ea (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-05T12:45:57Z (GMT) No. of bitstreams: 2 jorge_augusto_barroso.pdf: 605983 bytes, checksum: 4317652388abdb60186382b0434386ea (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-05T12:46:36Z (GMT) No. of bitstreams: 2 jorge_augusto_barroso.pdf: 605983 bytes, checksum: 4317652388abdb60186382b0434386ea (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Made available in DSpace on 2015-01-05T12:46:36Z (GMT). No. of bitstreams: 2 jorge_augusto_barroso.pdf: 605983 bytes, checksum: 4317652388abdb60186382b0434386ea (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Previous issue date: 2013 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Foram avaliados os Longissimus dorsi et lumborum (LTL), Semitendinosus (ST) e Triceps brachii (TB) obtidos de seis animais ?Guzer? ?Nelore ?Simmental (Tri), seis animais ?Guzer? ?Nelore (GN) e seis animais ?Guzer? ?Holand?s (GH), recriados a pasto com suplementa??o, terminados em confinamento de 82 dias e abatidos aos 24 meses. Foram mensurados o pH24horas, a capacidade de reten??o de ?gua, luminosidade (L*), teor de prote?na total, extrato et?reo, mat?ria seca, res?duo mineral fixo, teor de vermelho (a*), teor de amarelo (b*), croma (C*), matiz (H*), perdas de peso por cozimento, teor de col?geno total e sol?vel, ?ndice de fragmenta??o miofibrilar e for?a de cisalhamento. N?o houve efeito significativo (P>0,05) dos grupos gen?ticos sobre o pH24horas do LTL (5,64), do ST (5,72) e TB (5,85). Os valores de pH24horas do LTL, refer?ncia ? carca?a, estiveram dentro do intervalo de normalidade (5,3-5,7). Os grupos gen?ticos tamb?m n?o influenciaram, significativamente, o teor de extrato et?reo, os teores de prote?na e mat?ria seca, res?duo mineral fixo, teor de amarelo, o matiz, as perdas de peso por cozimento, o ?ndice de fragmenta??o miofibrilar, assim como o teor de col?geno total e sol?vel. A for?a de cisalhamento e a capacidade de reten??o de ?gua foram, no entanto, influenciados pelos grupos gen?ticos, observando maior maciez no grupo GH, em rela??o ao GN. A capacidade de reten??o de ?gua apresentou maiores valores para o grupo GN em rela??o ao grupo GH, o que n?o demonstrou impacto sobre as principais qualidades comerciais da carne. O teor de vermelho e o croma apresentaram intera??es entre os grupos gen?ticos e os m?sculos estudados, sendo a varia??o dentro do grupo GH, diferente dos demais grupos gen?ticos, apresentando valores menores no ST, em rela??o aos demais grupos gen?ticos, e, substancialmente, maiores valores no TB em rela??o aos demais m?sculos. Comparando-se as caracter?sticas entre os diferentes m?sculos, foram percebidas diferen?as significativas em todos os par?metros estudados, dentre elas a menor for?a de cisalhamento do TB, e tamb?m do ST em rela??o ao LTL. Tal fato talvez seja decorrente do maior teor de extrato et?reo, das menores perdas de peso por cozimento do TB e do maior ?ndice de fragmenta??o miofibrilar do TB e ST. Admite-se, tamb?m, que varia??es em par?metros, quando comparados LTL, ST e TB entre si, decorram de especificidades anat?micas e fisiol?gicas dos m?sculos que os originaram. Conclui-se que, os grupos gen?ticos apresentaram semelhan?a em quase todos os par?metros de qualidade estudados, demonstrando, por?m, menores valores de for?a de cisalhamento para o grupo GH. Foi tamb?m representativa a melhor qualidade do TB, medida por par?metros objetivos, em rela??o aos demais m?sculos estudados. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Zootecnia, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2013. / ABSTRACT Were tested Longissimus dorsi et lumborum (LTL), Semitendinosus (ST) e Triceps brachii (TB) obtained from six animals ?Guzer? ?Nellore ?Simmental (Tri), six animals ?Guzer? ?Nellore (GN) and six ?Guzer? ?Holstein (GH) recreated with pasture supplementation, 82 days in feedlot and slaughtered at 24 months. We measured the pH24hors, the ability to retain water, lightness (L*), total protein, ether extract, dry matter, fixed mineral residue, redness (a*), yellowness (b*), chroma (C*), hue (H*), cooking weight loss, total collagen and soluble, myofibrillar fragmentation index and shear force. There was no significant effect on pH 24hours (P> 0.05) between the genetic groups on the LTL (5.64), ST (5.72) and TB (5.85). The PH 24hours values of LTL, the reference substrate, were within the normal range (5.3 to 5.7). Genetic groups did not significantly influence the content of fat, the protein, dry matter and mineral, the yellowness, the hue, the weight losses by cooking, myofibrillar fragmentation index, as well as the content of total and soluble collagen. The shear force and the water retention capacity were influenced by genetic groups. The GH group was more tenderness than in the GN group. The capacity of water retention was higher in the GN group than in the GH group, which showed no impact on the main commercial qualities of meat. The content of red and chroma showed interactions among genetic groups and the muscles studied, and the variation in the GH group unlike other genetic groups had lower values in the ST and the other genetic groups had substantially higher values for TB compared to other muscles. Comparing the properties of the different muscles, significant differences were observed in all parameters studied, among them the lowest shear force of TB, and also the ST compared to LTL. This fact might be due to the higher content of fat, the less weight loss by cooking the TB and higher myofibrillar fragmentation index of TB and ST. Also it is assumed that variations in parameters when compared LTL, ST and TB among themselves, might be resulting of anatomical and physiological peculiarities of the muscles that originated them. We can conclude that the genetic groups were similar in almost all quality parameters studied, but lower values of shear force on the GH group. Also was relevant the best quality of TB, measured by objective parameters, compared to the other muscles studied.

Orientador: Nilo Sérgio Sabbião Rodrigues / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-22T11:11:16Z (GMT). No. of bitstreams: 1 Moraes_Fabianede_M.pdf: 11400492 bytes, checksum: ccae3b13c04ead483ac2377969757130 (MD5) Previous issue date: 2013 / Resumo: A carne assada, um item bem aceito pelos clientes de restaurantes coletivos, é comumente preparado com lagarto bovino (músculo Semitendinosus). O mercado da alimentação fora de casa está em franca expansão. Para atender à maior demanda dos restaurantes de coletividade, é necessário o aumento da produção e a busca e aprimoramento de tecnologias. O preparo de alimentos pelo sistema cook chill preserva as características sensoriais, reduz as perdas de processo, e resulta em alimento mais padronizado e microbiologicamente mais estável, quando comparado com sistemas convencionais, permitindo melhor programação e centralização da produção. Visando à comparação destes dois sistemas para a produção de lagarto bovino, na Etapa I desse estudo foi executado um planejamento experimental para a maximização do rendimento e da força de cisalhamento no produto processado pelo sistema cook chill. Foi aplicado um delineamento composto central rotacional para as variáveis independentes: tempo de cozimento, escala de injeção de vapor e temperatura do forno. Para a definição dos níveis das variáveis independentes foram realizados estudos preliminares. Foram obtidos maiores rendimentos no cozimento com menores tempos de cocção, maiores escalas de injeção de vapor e temperaturas intermediárias. A carne cozida a 177,7 °C apresentou menor força de cisalhamento, que é maior com o aumento do tempo de cozimento. Para a Etapa II, foram selecionados dois tratamentos dentre os dezessete do sistema cook chill da Etapa I: um de mínima força de cisalhamento (cook chill 1) e outro de máximo rendimento no cozimento (cook chill 2), os quais foram comparados com o sistema convencional por análises físico químicas, microbiológicas e sensoriais, no processamento e durante a estocagem. Os dois sistemas propiciaram carne assada de boa qualidade, em relação aos parâmetros analisados. As carnes processadas pelo sistema cook chill obtiveram melhor avaliação para os atributos sensoriais: aparência e gosto salgado. Embora a carne processada pelo sistema convencional tenha sido mais bem avaliada no atributo textura no corte com a faca e sua força de cisalhamento tenha sido a maior, não houve diferença significativa para o atributo textura na mastigação. A maior oxidação lipídica encontrada no lagarto processado pelo sistema cook chill 2 não impactou nos resultados da análise sensorial. Obteve-se carne com boa qualidade microbiológica até o quinto dia de estocagem nos três processamentos, destacando-se a carne processada pelo sistema cook chill 1 pelas baixas contagens microbianas mesmo no décimo dia de estocagem. Assim, o processamento de carne assada pelo sistema cook chill é vantajoso, principalmente, por permitir a produção de alimento com características mais estáveis, propiciar melhor programação e favorecer o aumento e a centralização da produção em restaurantes de coletividade / Abstract: Roast beef is a well accepted item by food service customers and it is commonly prepared with Semitendinosus beef. The food service market is currently booming. To meet the higher demands, it is necessary to increase production, develop new technologies as well as improve existing ones. Food preparation by the cook chill system preserves sensory characteristics, reduces water loss and delivers more standardized and microbiologically stable food, when compared to conventional systems, allowing better planning and centralization of production. In order to compare these two systems in terms of production of Semitendinosus muscle, Phase I of this study involved an experimental design to maximize cooking yield and shear force on the product processed by cook chill system. It was applied a central composite design for the independent variables: cooking time, steam scale injection and oven temperature. To define the levels of these independent variables preliminary studies were performed. Cooking yield is maximized when time is reduced, and higher scales of steam injection and intermediate temperatures are applied. The meat cooked at 177.7 ° C had lower shear force which increases when cooking time increases. For Phase II, two treatments were selected from the seventeen treatments in Phase I: one of minimal shear force (cook chill 1) and another of maximum cooking yield (cook chill 2), which were compared with the conventional system using physical chemical, microbiological and sensorial analysis during processing and storage. The two processing systems, cook chill and conventional, resulted in roast beef of good quality, in relation to the analyzed parameters. Meats processed using the cook chill system had better sensory evaluation in terms of the following attributes: appearance and salty taste. Although meat processed by the conventional system were more thoroughly evaluated in terms of cutting texture and had the biggest shear force, there was no significant difference in the mouth texture attribute between the samples. The higher lipid oxidation found on the meat processed by cook chill 2 system did not impact the sensorial analysis results. Meat with good microbiological quality were obtained up to the fifth day of storage for the three cases, especially for meat processed by cook chill 1 system, that showed low results until the tenth day of storage. Roast beef processing by cook chill system is advantageous, especially because of its ability to produce food that is higher in terms of stability, provide better programming and promote the increase and centralization of production in food service / Mestrado / Consumo e Qualidade de Alimentos / Mestra em Alimentos e Nutrição

A hérnia perineal é uma das afecções cirúrgicas frequentemente observadas na rotina da clínica cirúrgica de pequenos animais e acometem na sua maioria, cães machos, não castrados e acima de cinco anos. Apresenta elevado índice de recidivas e complicações pós-cirúrgicas, e devido a este fato, muitas técnicas foram preconizadas e utilizadas para a sua correção. Os objetivos do presente estudo foram avaliar a locomoção cinética dos cães com hérnia perineal bilateral, submetidos à técnica de transposição do músculo semitendinoso antes e após a sua transposição; verificar a capacidade de adaptação do membro pélvico operado, após a transposição do semitendinoso, até 90 dias de pós-operatório e analisar a viabilidade dessa técnica de reparação em casos de hérnia perineal bilateral. Foram operados onze cães com diagnostico de hérnia perineal bilateral, no Serviço de Cirurgia de Pequenos Animais junto ao Hospital Veterinário da Faculdade de Medicina Veterinária da Universidade de São Paulo (HOVET-FMVZ / USP). Todos foram submetidos à técnica de transposição do músculo e avaliados com exames baropodométricos antes e após a cirurgia, nos períodos de 30, 60 e 90 dias pós-operatório. As variáveis pico de força vertical (PFV) e impulso vertical (IV) foram utilizadas como parâmetros para a análise de mudanças na locomoção. A PFV e IV não mostraram diferença estatística (p> 0,05) entre os membros operados e não operados, respectivamente (18,62 0 &plusmn 4,93 e 18,51 &plusmn 3,75), indicando que não houve alteração na locomoção dos cães após a transposição do músculo semitendinoso. A diferença no comportamento dessas variáveis no período pré-operatório nos permitiu aferir que o desconforto provocado pela hérnia perineal possa interferir na locomoção do animal gerando assimetria, considerando que após o procedimento operatório a simetria da locomoção apresentou valores mais compatíveis dentro do normal. As diferenças em PFV e IV, embora não significativas, nos dá uma idéia da recuperação desses cães e sugere que a transposição não afeta a função locomotora do membro operado. / A perineal hernia is a surgical lesion frequently observed in surgical clinic for small animals, affecting mainly dogs neutered over five years. Has a high recurrence rate and postoperative complications, and due to this fact, many techniques have been proposed and used for its correction. The objectives of this study were to evaluate the kinetic movement of dogs with bilateral perineal hernia, submitted to the technique of transposition of the semitendinosus muscle before and after its implementation and verify the adaptability of the pelvic limb surgery, after transposition of the semitendinosus 90 days of postoperatively and analyze the feasibility of this technique of repair in cases of bilateral perineal hernia. Eleven dogs were operated with diagnosis of bilateral perineal hernia, on the Surgery Service of the animal small of the Veterinary Hospital of the Faculty of Veterinary Medicine, University of São Paulo (HOVET-FMVZ / USP). All patients underwent the technique of muscle transposition and evaluated baropodometric examinations before and after surgery, in periods of 30, 60 and 90 days postoperatively. The variables peak vertical force (PFV) and vertical impulse (VI) were used as parameters for the analysis of changes in locomotion. The PFV and IV showed no statistical difference (p> 0.05) between the operated and non operated limbs, respectively (18.62 &plusmn 4.93 and 18.51 &plusmn 3.75), indicating that there was no change in locomotion dogs after the transposition of the semitendinosus muscle. The difference in behavior of these variables in the preoperative period allowed us to infer that the discomfort caused by perineal hernia can interfere with the locomotion of the asymmetry animal generating, whereas after the operative procedure, the symmetry of locomotion showed more next values of the normal. The difference in PFV and IV, although not significant, gives us an idea of the recovery of these dogs and suggests that the transposition does not affect the motor function of the limb.

A hérnia perineal é uma das afecções cirúrgicas frequentemente observadas na rotina da clínica cirúrgica de pequenos animais e acometem na sua maioria, cães machos, não castrados e acima de cinco anos. Apresenta elevado índice de recidivas e complicações pós-cirúrgicas, e devido a este fato, muitas técnicas foram preconizadas e utilizadas para a sua correção. Os objetivos do presente estudo foram avaliar a locomoção cinética dos cães com hérnia perineal bilateral, submetidos à técnica de transposição do músculo semitendinoso antes e após a sua transposição; verificar a capacidade de adaptação do membro pélvico operado, após a transposição do semitendinoso, até 90 dias de pós-operatório e analisar a viabilidade dessa técnica de reparação em casos de hérnia perineal bilateral. Foram operados onze cães com diagnostico de hérnia perineal bilateral, no Serviço de Cirurgia de Pequenos Animais junto ao Hospital Veterinário da Faculdade de Medicina Veterinária da Universidade de São Paulo (HOVET-FMVZ / USP). Todos foram submetidos à técnica de transposição do músculo e avaliados com exames baropodométricos antes e após a cirurgia, nos períodos de 30, 60 e 90 dias pós-operatório. As variáveis pico de força vertical (PFV) e impulso vertical (IV) foram utilizadas como parâmetros para a análise de mudanças na locomoção. A PFV e IV não mostraram diferença estatística (p> 0,05) entre os membros operados e não operados, respectivamente (18,62 0 &plusmn 4,93 e 18,51 &plusmn 3,75), indicando que não houve alteração na locomoção dos cães após a transposição do músculo semitendinoso. A diferença no comportamento dessas variáveis no período pré-operatório nos permitiu aferir que o desconforto provocado pela hérnia perineal possa interferir na locomoção do animal gerando assimetria, considerando que após o procedimento operatório a simetria da locomoção apresentou valores mais compatíveis dentro do normal. As diferenças em PFV e IV, embora não significativas, nos dá uma idéia da recuperação desses cães e sugere que a transposição não afeta a função locomotora do membro operado. / A perineal hernia is a surgical lesion frequently observed in surgical clinic for small animals, affecting mainly dogs neutered over five years. Has a high recurrence rate and postoperative complications, and due to this fact, many techniques have been proposed and used for its correction. The objectives of this study were to evaluate the kinetic movement of dogs with bilateral perineal hernia, submitted to the technique of transposition of the semitendinosus muscle before and after its implementation and verify the adaptability of the pelvic limb surgery, after transposition of the semitendinosus 90 days of postoperatively and analyze the feasibility of this technique of repair in cases of bilateral perineal hernia. Eleven dogs were operated with diagnosis of bilateral perineal hernia, on the Surgery Service of the animal small of the Veterinary Hospital of the Faculty of Veterinary Medicine, University of São Paulo (HOVET-FMVZ / USP). All patients underwent the technique of muscle transposition and evaluated baropodometric examinations before and after surgery, in periods of 30, 60 and 90 days postoperatively. The variables peak vertical force (PFV) and vertical impulse (VI) were used as parameters for the analysis of changes in locomotion. The PFV and IV showed no statistical difference (p> 0.05) between the operated and non operated limbs, respectively (18.62 &plusmn 4.93 and 18.51 &plusmn 3.75), indicating that there was no change in locomotion dogs after the transposition of the semitendinosus muscle. The difference in behavior of these variables in the preoperative period allowed us to infer that the discomfort caused by perineal hernia can interfere with the locomotion of the asymmetry animal generating, whereas after the operative procedure, the symmetry of locomotion showed more next values of the normal. The difference in PFV and IV, although not significant, gives us an idea of the recovery of these dogs and suggests that the transposition does not affect the motor function of the limb.

Orientador: Antonio Carlos de Moraes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação Fisica / Made available in DSpace on 2018-08-06T00:40:44Z (GMT). No. of bitstreams: 1 Rodrigues_CarlosEduardoBassi_M.pdf: 2031180 bytes, checksum: f6f3b959e94c9e434232c8d18c9436d2 (MD5) Previous issue date: 2005 / Resumo: Os estudos envolvendo a eletromiografia associada ao dinamômetro isocinético tem sido fundamental para o conhecimento da participação dos músculos e quantificação do torque relacionado à articulação do joelho em atletas que praticam a modalidade futebol em nível competitivo. Esta modalidade é caracterizada por movimentos explosivos e dinâmicos que exigem força rápida e resistência muscular. Estas características estão intimamente relacionadas com a função desempenhada pelos Ísquiotibiais, o que nos leva a acreditar na importância do conhecimento deste grupo muscular em relação à modalidade esportiva. O presente estudo objetivou analisar o comportamento dos sinais EMG dos músculos Bíceps Femoral (cabeça longa) e Semitendíneo e o torque articular do joelho, durante a realização de movimentos no dinamômetro isocinético. Participaram do estudo 14 atletas de futebol da categoria Juniores (18-20 anos) da Associação Atlética Ponte Preta. Os mesmos foram submetidos a um protocolo de cinco repetições de flexão (ação concêntrica e excêntrica) do joelho esquerdo em 3 velocidades (60, 180 e 300 graus/segundo), as quais foram previamente sorteadas. Entre a realização de cada velocidade houve um período de 3 minutos para repouso. A atividade eletromiográfica (EMG) foi coletada utilizando-se eletrodos de superfície e os dados foram expressos em RMS. Com relação ao RMS houve alteração entre os músculos em algumas repetições na fase concêntrica a 60°/s e de forma geral os valores expresso RMS não se alteraram com a variação da velocidade de execução bem como do tipo de contração realizada. Com relação ao torque, os maiores valores foram obtidos na velocidade de 60°/s durante a fase concêntrica. Na fase excêntrica, não houve alteração do torque com modificação da velocidade de execução. Além disso, independentemente da velocidade ou repetição considerada, os valores de torque foram maiores durante a fase excêntrica. A relação RMS/Torque não foi linear nestas condições de avaliação, pois enquanto os valores de torque variaram entre as velocidades e entre os dois tipos de contração, o RMS manteve-se praticamente estável / Abstract: Studies involving electromyography associated with isokinetic dynamometer are important do identify muscles participation and torque quantification related with knees articulation in competitive soccer¿s athlete. Explosive and dynamic movements that demand muscular resistance and explosive strength characterize soccer. These characteristics are related with the role played by isquiotibial muscle, which take us to understand the importance of studding these muscular groups in. This study aimed to analyze the electromyography data of the Biceps Femoris and Semitendinosus muscles and the knee¿s torque during the movements in the isokinetic dynamometer. To participate of the study 14 athletes soccer¿s players wore selected from the Junior¿s category (18-20 years old) of the Ponte Preta Athletic Association. They executed a protocol of 5 repetitions of flexion (concentric and eccentric action) of the left knee in three velocities (60, 80 and 120 degrees/seconds) randomly. There was a 3 minutes rest between the executions. The electromyography data was collected with surface electrodes and data expressed with RMS. The RMS data had some variation between the two muscles in some repetitions of the concentric phase at 60º/s and generally the RMS data had no variation in the three velocities or in the two different muscle¿s contraction. For the torque, the highest data was from the 60º/s velocity in concentric contraction. For the eccentric contraction there was no torque¿s variation in the different velocities. Moreover, independent of velocities or repetitions eccentric phase had higher data for the torque. The relation RMS/torque was not constant because torque data changed during different velocities and different contraction and RMS kept almost stabled. / Mestrado / Mestre em Educação Física

No description available.

Musculoskeletal injuries are commonly associated with muscle atrophy as a function of immobilization or change of normal function. For example, injuries to the anterior cruciate ligament (ACL) which may involve ligament reconstruction, results in the "quadriceps avoidance" gait which leads to atrophy of the knee extensormuscles. In these situations it is not clear whether or not the atrophy is associated with loss of specific muscle fibre types with accompanying functional deficits. Such knowledge would be helpful in implementing exercise regimes designed to compensate for loss of particular fibre types. It is believed that isokinetic exercise performed at speeds below 180° per second strengthens type I muscle fibres, and type II fibres at fast speeds. However, there is no evidence to indicate the specific muscle fibre response to different rates of muscle contraction. Identification of muscle fibre type is most directly determined by biopsy technique but is too invasive for a routine measurement. Electromyography median frequency has been used as a non-invasive measure to infer muscle fibre composition in various studies. However, the reliability and accuracy of this technique has been questioned and improvement is necessary. This research was designed to provide a more accurate and reliable protocol for the determination of EMG median frequency which may be used, after validation against more direct biopsy techniques, as a routine method for inferring muscle fibre composition. The investigation also explored the muscular response as measured by EMG median frequency to varying speeds of muscle contraction, fatiguing exercise and atrophy following ACL reconstruction. The ultimate aim of this research was to improve the reliability of the determination of EMG median frequency to enhance its application as a predictor of muscle fibre composition. This provides information which may improve ACL rehabilitation programs designed to restore and prevent specific muscle fibre types loss that have not previously been targeted by current rehabilitation programs. This research was conducted in three studies. Study one determined the stability of the EMG median frequency bilaterally for the quadriceps and hamstrings muscles and identified the mode of contraction associated with the greatest reliability. The strength and EMG median frequency of the vastus lateralis, medial hamstrings and vastus medialis of 55 subjects was determined across 5 speeds from 0° to 240° per second using a Kin-Com isokinetic dynamometer and an EMG data acquisition system. Isometric contraction was found to have the least bilateral discrepancy (4.01% ±3.06) and between trials standard deviation (4.50) in the vastus lateralis, medial hamstrings and vastus medialis. Study two investigated the EMG median frequency changes in the vastus lateralis which occur immediately following different speeds of isokinetic exercise to the point of fatigue in normal subjects. Thirty-four subjects participated in the study, and performed a 90-second period of isokinetic exercise to activate the knee extensors at either 30° or 300° per second. EMG median frequency of the vastus lateralis was determined before, immediately after and 7 minutes after the fatiguing exercise. The percentage drop in EMG median frequency of the vastus medialis was gnificantly (p<0.05) greater after slow speed (27.9%) than fast speed (20.25%) exercise, while no significant difference was found for the percentage drop in extension torque. Full recovery was found 7 minutes after the fatiguing exercise. By reference to previous research showing a relationship between EMG median frequency and muscle fibre type, an increase in activation of type I muscle fibres with slow speed exercise and an increase in type II muscle fibres with fast speed exercise was observed. Study three identified the changes in EMG median frequency following ACL reconstruction and evaluated the bilateral differences in EMG median frequency of the knee muscles. The relationships between EMG median frequency and the measures of knee functional ability, knee muscle strength, age and time since surgery were also investigated. Twelve subjects who had undergone ACL reconstruction using a semitendinosus and gracilis graft 6 to 12 months earlier, participated in the study. EMG median frequency was determined from an 8-second isometric contraction and knee functional ability was assessed using the Cincinnati Rating Scale. Bilateral EMG median frequency shifts were inconsistent among subjects. On the basis of previous research which indicated a relationship between EMG median frequency and fibre type, no consistent pattern of muscular fibre type atrophy subsequent to ACL reconstruction occurred within 6 to 12 months (ranged from -43 to 57 Hz). Additionally, no significant correlations were found between the EMG median frequency and the knee functional score and knee extension and flexion torques, age, time since operation and the bilateral differences in EMG median frequency. The results of this investigation will serve to improve the reliability of EMG median frequency across a range of conditions in which it has been evaluated. Further research is needed to confirm the relationship between EMG median frequency and direct observations of muscle fibre composition to improve the predictive value of this measure. Following this validation it will be possible to evaluate the bilateral EMG median frequency shift to infer the type of muscle fibre atrophy, and use this measure in determining the efficacy of specific rehabilitation programs. In conclusion * An 8-second isometric contraction is recommended for determining EMG median frequency. * EMG median frequency of a muscle decreases significantly more after slow fatiguing exercise than after fast speed fatiguing exercise. * There was no generalised bilateral EMG median frequency shift found in a group of subjects 6 to 12 months following semitendinosus and gracilis graft ACL reconstruction. * The results of this study will serve to improve the reliability of procedures used to determine EMG median frequency under a range of different contractile conditions. The EMG median frequency changes in response to these conditions require further validations with muscle biopsy in future.

No description available.