Introduction: It has been proposed that inadequate rest intervals may contribute to decreased performance of activities. However, previous research has not investigated the effect of rest interval on performance of the Star Excursion Balance Test (SEBT) in individuals with and without chronic ankle instability. Objective: To determine whether rest interval affects performance of the SEBT associated with chronic ankle instability (CAI) and whether neuromuscular function, postural control or biomechanics can be associated factors which may help discriminate between healthy individuals and those with CAI during the SEBT. Design: 2-group counterbalanced study. Participants: Participants included 24 individuals with a history of at least one ankle sprain in the past year and at least 2 episodes of giving way in the past 6 month prior to study enrollment, and 24 individuals with no history of ankle sprain or instability in their lifetime. Methods: Subjects completed 3 trials in each of the 3 reach directions (anteromedial, medial, posteromedial) in random order. A total of three visits were required in order to complete the 3 rest intervals (10, 20, 40 seconds). Normalized maximum reach distance, electromyographic (EMG) activation of tibialis anterior, peroneus longus, and medial gastrocnemius muscles, multiplanar motion of the lower extremity, coupling angles (CA) of lower extremity segments and maximum lateral center of pressure velocity were calculated and compared between groups in each direction for each rest interval. Results: Rest interval did not influence differences of reach distance, EMG ankle muscle activation, kinematics and center of pressure velocity between healthy individuals and those with CAI during the SEBT. However, the rest interval of 20 seconds demonstrated differences in CAs of tibial internal rotation/dorsiflexion (TIR/DF) and tibial internal rotation/eversion (TIR/EV) between healthy individuals and those with CAI during the SEBT. Overall, reach distance, mean amplitude of EMG ankle muscles, kinematics and joint CAs were different between healthy individuals and those with CAI during the SEBT regardless of rest interval. Discussion: Based on these results, differences exist in neuromuscular functions and biomechanics between healthy individuals and those with CAI when performing the SEBT. A rest interval time of 20 seconds between trials during the SEBT is an appropriate time to discriminate joint CAs of TIR/DF and TIR/EV between healthy individuals and those with CAI during the SEBT. These findings have implications for treatment and possible prevention of CAI.

A fadiga neuromuscular pode ser induzida por contrações isométricas sustentadas para determinar o desempenho funcional muscular do organismo humano ao longo dos anos. A finalidade desta pesquisa foi determinar o limiar de fadiga eletromiográfica dos músculos masseter e temporal (bilateral), por meio do espectro da frequência mediana (FM), de crianças, jovens, adultos e idosos, com intuito de traçar parâmetros que possam ser considerados normais em função da idade. Cento e setenta indivíduos brasileiros dentados completos (exceto o Grupo I com dentição mista) sem disfunção temporomandibular foram distribuídos em cinco Grupos Etários: I (7-12 anos, n=38), II (13-20 anos, n=36), III (21-40 anos, n=40), IV (41-60 anos, n=40) e V (61-80 anos, n=16). Foi utilizado o eletromiógrafo Myosystem-Br1 para análise do sinal EMG normalizado na condição de fadiga muscular. Os dados da FM do sinal EMG foram obtidos pelos valores do janelamento de 5s durante o período inicial (PI), médio (PM) e final (PF) do sinal EMG. O apertamento dental em contração voluntária máxima foi o fator que determinou a fadiga muscular e normalizou os dados EMG que foram tabulados e submetidos para análise estatística (ANOVA e medidas repetidas; SPSS 22.0; p < 0,05). Foram encontradas diferenças estatísticas significantes entre as faixas etárias no PM (p=0,05) para o músculo temporal direito; PI (p=0,02) e PF (p=0,01) para o músculo temporal esquerdo. Houve decréscimo linear da FM entre os períodos do sinal EMG para todos os grupos etários em relação aos músculos masseteres e temporais, com diferenças estatísticas significantes, exceto masseter esquerdo Grupo V (p=0,00 para cada análise). Baseados nos resultados desta pesquisa, o fator idade influenciou o sinal eletromiográfico normalizado no processo de fadiga neuromuscular e demonstrou que existe declínio linear no decorrer do sinal eletromiográfico para os músculos masseter e temporal. Este estudo contribuiu para a comunidade científica, porque demonstrou parâmetros do sinal eletromiográfico de indivíduos saudáveis na condição de fadiga durante o envelhecimento humano, adequados para serem utilizados em trabalhos futuros de comparação do sistema muscular esquelético saudável e com alterações morfofuncionais. / Neuromuscular fatigue can be induced by sustained isometric contractions to determine the functional muscular performance of the human body over the years. The aim of this research was to determine the EMG fatigue threshold of the masseter and temporal muscle (bilateral), through the median frequency (MF) spectrum, of children, young adults and elderly, in order to draw parameters that can be considered normal according to age. A total of 170 full-toothed Brazilian subjects (except Group I with mixed dentition) without temporomandibular dysfunction were distributed in five Age Groups: I (7-12 years, n = 38), II (13-20 years, n = 36), III 21-40 years, n = 40), IV (41-60 years, n = 40) and V (61-80 years, n = 16). The Myosystem-Br1 electromyograph was used to analyze the normalized EMG signal in the muscular fatigue condition. The MF data of the EMG signal were obtained by the windowing values of 5s during the initial period (IP), mean (MP) and final (FP) of the EMG signal. The teeth clenching in maximal voluntary contraction was the factor that determined muscle fatigue and normalized the EMG data that were tabulated and submitted to statistical analysis (ANOVA and repeated measures, SPSS 22.0, P <0.05). Significant statistical differences were found between the age groups in the MP (p = 0.05) for the right temporal muscle; IP (P = 0.02) and FP (P = 0.01) for left temporal muscle. There was a linear decrease in MF between the EMG signal periods for all age groups in relation to the masseter and temporalis muscles, with significant statistical differences, except left masseter - Group V (P = 0.00 for each analysis). Based on the results of this research, the age factor influenced the normalized EMG signal in the process of neuromuscular fatigue and demonstrated that there is a linear decline during the EMG signal for the masseter muscle and temporal muscle. This study should be useful for the scientific community because it demonstrates parameters of the EMG signal of healthy individuals in fatigue condition during human aging, suitable for use in future studies of comparison of healthy skeletal muscle system with morphofunctional changes

A osteoporose é uma das doenças mais comuns que atinge a população idosa, que afeta todos os ossos, inclusive a maxila e mandíbula. Esta é definida como uma doença óssea metabólica crônica e progressiva, em que ocorre uma perda generalizada de massa óssea. Este estudo teve por objetivo avaliar o limiar de fadiga eletromiográfica dos músculos masseter e temporal, bilateralmente, em indivíduos com osteoporose e saudáveis durante o período de cinco segundos inicial, médio e final do sinal coletado. Participaram desta pesquisa 66 indivíduos com idade entre 45 a 75 anos (idade média de 53,9 ± 1,47 anos) de ambos os gêneros. Estes foram divididos igualmente em dois grupos: GO - Grupo Osteoporose e GC - Grupo Controle, constituído por indivíduos saudáveis, pareados sujeito a sujeito, por gênero, idade, peso e estatura. Os participantes desta pesquisa foram submetidos à avaliação eletromiográfica utilizando o aparelho Myosystem - Br1_P84, durante as condições clínicas de contração voluntária máxima por 10 segundos (fator de normalização) e contração voluntária máxima por tempo indeterminado (condição clínica de análise do limiar de fadiga). A fadiga eletromiográfica foi analisada por meio da mensuração do espectro da frequência mediana (Hz). Os dados eletromiográficos normalizados foram tabulados e analisados utilizando o programa estatístico SigmaPlot 11.0. (p<0,05). Observou-se que houve redução do tempo de fadiga no grupo GO - Osteoporose. Na análise do limiar de fadiga eletromiográfica comparando os períodos inicial, médio e final, verificou-se que houve fadiga muscular para ambos os grupos. Na análise individual dos períodos inicial, médio e final, comparando os Grupos Osteoporose e Controle, verificou-se que não houve diferença estatística. Na comparação entre os gêneros, para cada um dos períodos, nos Grupos Osteoporose e Controle, também não foi verificada diferença estatística, embora as mulheres tenham apresentado maior valor de frequência mediana. Na análise da porcentagem de diminuição do limiar de fadiga eletromiográfica para os Grupos Osteoporose e Controle observou-se que houve fadiga muscular para os grupos avaliados, com redução significante e de forma desequilibrada para o Grupo Osteoporose. Nossos resultados permitem concluir que a osteoporose nos ossos da face acarreta alterações musculares, afetando desta forma, o funcionamento do sistema estomatognático. / Osteoporosis is one of the most common diseases affecting the elderly population, which affects all bones, including the maxilla and mandible. It is a chronic and progressive metabolic bone disease that causes loss of bone mass. This study evaluated the electromyographic fatigue threshold of masseter and temporal muscles, bilaterally, in individuals with osteoporosis and healthy during three periods: five initial seconds, five middle seconds and five final seconds of the collected signal. A total of 66 individuals aged 45 to 75 years (mean age 53.9 ± 1.47 years) of both genders were divided into two groups: GO - Osteoporosis Group and GC - Control Group, consisting of healthy individuals matched subject to subject, by gender, age, weight and height. It was used Myosystem-electromyographic Br1_P84, during the clinical conditions of maximum voluntary contraction for 10 seconds (normalization factor) and maximum voluntary contraction indefinitely (clinical condition of fatigue threshold analysis). Electromyographic fatigue was analyzed by measuring the spectrum of the median frequency (Hz). The normalized electromyographic data were tabulated and analyzed by the statistical program SigmaPlot 11.0 (p<0.05). Group GO - Osteoporosis presented a reduction in fatigue time. In the analysis of the threshold of electromyographic fatigue by comparing the initial, middle and final periods, it was observed that Osteoporosis and Control groups presented muscle fatigue. Individual analysis of the initial, middle and final periods, comparing the Osteoporosis and Control Groups, showed no statistical difference. The comparison between genders, for each of the periods, in the Osteoporosis and Control Groups, showed no statistical difference too, although the women presented a higher median frequency. The analysis of the percentage decrease of electromyographic fatigue threshold for Osteoporosis and Control Groups revealed muscle fatigue for both groups, with significant reduction and unbalanced for Osteoporosis Group. Our results lead to the conclusion that osteoporosis in the face bones causes muscle changes, affecting the function of the stomatognathic system.

A osteoporose é uma das doenças mais comuns que atinge a população idosa, que afeta todos os ossos, inclusive a maxila e mandíbula. Esta é definida como uma doença óssea metabólica crônica e progressiva, em que ocorre uma perda generalizada de massa óssea. Este estudo teve por objetivo avaliar o limiar de fadiga eletromiográfica dos músculos masseter e temporal, bilateralmente, em indivíduos com osteoporose e saudáveis durante o período de cinco segundos inicial, médio e final do sinal coletado. Participaram desta pesquisa 66 indivíduos com idade entre 45 a 75 anos (idade média de 53,9 ± 1,47 anos) de ambos os gêneros. Estes foram divididos igualmente em dois grupos: GO - Grupo Osteoporose e GC - Grupo Controle, constituído por indivíduos saudáveis, pareados sujeito a sujeito, por gênero, idade, peso e estatura. Os participantes desta pesquisa foram submetidos à avaliação eletromiográfica utilizando o aparelho Myosystem - Br1_P84, durante as condições clínicas de contração voluntária máxima por 10 segundos (fator de normalização) e contração voluntária máxima por tempo indeterminado (condição clínica de análise do limiar de fadiga). A fadiga eletromiográfica foi analisada por meio da mensuração do espectro da frequência mediana (Hz). Os dados eletromiográficos normalizados foram tabulados e analisados utilizando o programa estatístico SigmaPlot 11.0. (p<0,05). Observou-se que houve redução do tempo de fadiga no grupo GO - Osteoporose. Na análise do limiar de fadiga eletromiográfica comparando os períodos inicial, médio e final, verificou-se que houve fadiga muscular para ambos os grupos. Na análise individual dos períodos inicial, médio e final, comparando os Grupos Osteoporose e Controle, verificou-se que não houve diferença estatística. Na comparação entre os gêneros, para cada um dos períodos, nos Grupos Osteoporose e Controle, também não foi verificada diferença estatística, embora as mulheres tenham apresentado maior valor de frequência mediana. Na análise da porcentagem de diminuição do limiar de fadiga eletromiográfica para os Grupos Osteoporose e Controle observou-se que houve fadiga muscular para os grupos avaliados, com redução significante e de forma desequilibrada para o Grupo Osteoporose. Nossos resultados permitem concluir que a osteoporose nos ossos da face acarreta alterações musculares, afetando desta forma, o funcionamento do sistema estomatognático. / Osteoporosis is one of the most common diseases affecting the elderly population, which affects all bones, including the maxilla and mandible. It is a chronic and progressive metabolic bone disease that causes loss of bone mass. This study evaluated the electromyographic fatigue threshold of masseter and temporal muscles, bilaterally, in individuals with osteoporosis and healthy during three periods: five initial seconds, five middle seconds and five final seconds of the collected signal. A total of 66 individuals aged 45 to 75 years (mean age 53.9 ± 1.47 years) of both genders were divided into two groups: GO - Osteoporosis Group and GC - Control Group, consisting of healthy individuals matched subject to subject, by gender, age, weight and height. It was used Myosystem-electromyographic Br1_P84, during the clinical conditions of maximum voluntary contraction for 10 seconds (normalization factor) and maximum voluntary contraction indefinitely (clinical condition of fatigue threshold analysis). Electromyographic fatigue was analyzed by measuring the spectrum of the median frequency (Hz). The normalized electromyographic data were tabulated and analyzed by the statistical program SigmaPlot 11.0 (p<0.05). Group GO - Osteoporosis presented a reduction in fatigue time. In the analysis of the threshold of electromyographic fatigue by comparing the initial, middle and final periods, it was observed that Osteoporosis and Control groups presented muscle fatigue. Individual analysis of the initial, middle and final periods, comparing the Osteoporosis and Control Groups, showed no statistical difference. The comparison between genders, for each of the periods, in the Osteoporosis and Control Groups, showed no statistical difference too, although the women presented a higher median frequency. The analysis of the percentage decrease of electromyographic fatigue threshold for Osteoporosis and Control Groups revealed muscle fatigue for both groups, with significant reduction and unbalanced for Osteoporosis Group. Our results lead to the conclusion that osteoporosis in the face bones causes muscle changes, affecting the function of the stomatognathic system.

A fadiga neuromuscular pode ser induzida por contrações isométricas sustentadas para determinar o desempenho funcional muscular do organismo humano ao longo dos anos. A finalidade desta pesquisa foi determinar o limiar de fadiga eletromiográfica dos músculos masseter e temporal (bilateral), por meio do espectro da frequência mediana (FM), de crianças, jovens, adultos e idosos, com intuito de traçar parâmetros que possam ser considerados normais em função da idade. Cento e setenta indivíduos brasileiros dentados completos (exceto o Grupo I com dentição mista) sem disfunção temporomandibular foram distribuídos em cinco Grupos Etários: I (7-12 anos, n=38), II (13-20 anos, n=36), III (21-40 anos, n=40), IV (41-60 anos, n=40) e V (61-80 anos, n=16). Foi utilizado o eletromiógrafo Myosystem-Br1 para análise do sinal EMG normalizado na condição de fadiga muscular. Os dados da FM do sinal EMG foram obtidos pelos valores do janelamento de 5s durante o período inicial (PI), médio (PM) e final (PF) do sinal EMG. O apertamento dental em contração voluntária máxima foi o fator que determinou a fadiga muscular e normalizou os dados EMG que foram tabulados e submetidos para análise estatística (ANOVA e medidas repetidas; SPSS 22.0; p < 0,05). Foram encontradas diferenças estatísticas significantes entre as faixas etárias no PM (p=0,05) para o músculo temporal direito; PI (p=0,02) e PF (p=0,01) para o músculo temporal esquerdo. Houve decréscimo linear da FM entre os períodos do sinal EMG para todos os grupos etários em relação aos músculos masseteres e temporais, com diferenças estatísticas significantes, exceto masseter esquerdo Grupo V (p=0,00 para cada análise). Baseados nos resultados desta pesquisa, o fator idade influenciou o sinal eletromiográfico normalizado no processo de fadiga neuromuscular e demonstrou que existe declínio linear no decorrer do sinal eletromiográfico para os músculos masseter e temporal. Este estudo contribuiu para a comunidade científica, porque demonstrou parâmetros do sinal eletromiográfico de indivíduos saudáveis na condição de fadiga durante o envelhecimento humano, adequados para serem utilizados em trabalhos futuros de comparação do sistema muscular esquelético saudável e com alterações morfofuncionais. / Neuromuscular fatigue can be induced by sustained isometric contractions to determine the functional muscular performance of the human body over the years. The aim of this research was to determine the EMG fatigue threshold of the masseter and temporal muscle (bilateral), through the median frequency (MF) spectrum, of children, young adults and elderly, in order to draw parameters that can be considered normal according to age. A total of 170 full-toothed Brazilian subjects (except Group I with mixed dentition) without temporomandibular dysfunction were distributed in five Age Groups: I (7-12 years, n = 38), II (13-20 years, n = 36), III 21-40 years, n = 40), IV (41-60 years, n = 40) and V (61-80 years, n = 16). The Myosystem-Br1 electromyograph was used to analyze the normalized EMG signal in the muscular fatigue condition. The MF data of the EMG signal were obtained by the windowing values of 5s during the initial period (IP), mean (MP) and final (FP) of the EMG signal. The teeth clenching in maximal voluntary contraction was the factor that determined muscle fatigue and normalized the EMG data that were tabulated and submitted to statistical analysis (ANOVA and repeated measures, SPSS 22.0, P <0.05). Significant statistical differences were found between the age groups in the MP (p = 0.05) for the right temporal muscle; IP (P = 0.02) and FP (P = 0.01) for left temporal muscle. There was a linear decrease in MF between the EMG signal periods for all age groups in relation to the masseter and temporalis muscles, with significant statistical differences, except left masseter - Group V (P = 0.00 for each analysis). Based on the results of this research, the age factor influenced the normalized EMG signal in the process of neuromuscular fatigue and demonstrated that there is a linear decline during the EMG signal for the masseter muscle and temporal muscle. This study should be useful for the scientific community because it demonstrates parameters of the EMG signal of healthy individuals in fatigue condition during human aging, suitable for use in future studies of comparison of healthy skeletal muscle system with morphofunctional changes

Background: Individuals with cerebral palsy (CP) are prone to sedentary life with limited recreational- and physical activity. RaceRunning (RR) is a sport for individuals with disabilities such as motor impairment that allow them to move independently and enjoy physical activity. The aim of the study was to investigate muscle fatigue of RR athletes with different classiffcation of CP during six minuteRaceRunning test (6MRRT). The Cerebral Palsy International Sports and RecreationAssociation has the goal to make RR a Paralympic sport. For a sport to be included in the Paralympics a classiffcation system has to be made. Information about muscle function during RR could give vital physical information about athletes with CP and contribute to the development of such classiffcation system. Method: Median frequency of the power spectrum from surface electromyography(sEMG) of four muscles (vastus lateralis, biceps femoris, gluteus medius, gastrocnemius lateralis) was computed along with amplitude changes (root mean square) in order to assess muscle fatigue. Results: Indications of muscle fatigue were observed from one out of five athletes for athlete's less affected side. Further sEMG studies with more subjects have to be conducted on CP RR athletes to give more conclusive results of muscle fatigue.

Electric muscle stimulation (EMS) has been widely used in the rehabilitation of musculoskeletal injuries. Patterned electrical neuromuscular stimulation (PENS), a specific form of EMS, has been developed to better educate muscles to contract properly. The physiological efficacy of PENS has not been quantifiably identified. OBJECTIVES: The aim of this study is to determine the acute effect of one PENS training session (3 sets of 10 1-sec repetitions) on maximal isometric knee extensor (MVIC) torque production and surface EMG (sEMG) in healthy nonathlete college students. DESIGN: A randomized repeated-measures design was used in this study. METHODS: Twenty-two male college students participated in the study. All participants completed two training sessions, one with PENS and one without, in a randomized crossover design. RESULTS: One bout of PENS training significantly increased MVIC (3.1% ± 1.7%, p = 0.03) which was greater than the change in MVIC of the control group (p = 0.03). Control training did not alter MVIC but resulted in significant decrease in average sEMG amplitude (-7.8% ± 1.6%, p ≤ 0.01) and peak sEMG amplitude (-10.4% ± 2.7%, p ≤ 0.01). These reductions in sEMG following control training were significantly different from the PENS group (p = 0.03 and p ≤ 0.01). CONCLUSIONS: The findings suggest that strength training in conjunction with PENS can enhance torque production after just one bout of training. The increase in torque with no change in sEMG amplitude can be explained by increased motor unit synchronization or decreased cocontraction of antagonist muscles.

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.

O sinal EEG, cujas informações descrevem o comportamento elétrico do córtex cerebral, apesar de ser bastante utilizado para diagnósticos, principalmente de patologias como epilepsia, no Brasil ainda não é usual o monitoramento contínuo em ambiente de UTI em hospitais públicos. Diante disso, e partindo do pressuposto que estudos sobre o EEG normal, registrado em pessoas sem problemas neurológicos, são escassos, a criação de uma base de registros de EEG normal e análise quantitativa da mesma se faz necessária para que, por meio dos resultados obtidos, padrões normais possam ser estabelecidos e por meio deles a identificação de parâmetros patológicos se torne mais eficaz. Nesse projeto foi elaborada uma base de dados de EEG, com total de 100 registros válidos, advindos de voluntários normais e saudáveis. E a partir desses registros a situação de vigília e olhos fechados foi analisada sob o aspecto de três quantificadores distintos, sendo eles, Porcentagem de Contribuição de Potência (PCP), Frequência Mediana (FM) e Coerência, ambos avaliando o sinal no domínio da frequência. A fim de obter comparações para os resultados obtidos pela análise dos dados do EEG normal, foram utilizados 128 registros de EEG em situação de coma, com diferentes tipos de etiologias e desfechos. Os ritmos que apresentaram maiores distinções entre normal e coma foram Delta e Alfa, principalmente para o quantificador FM. Notou-se que o PCP avaliou características de potência e portanto sintetizou as informações de energia de cada ritmo cerebral tanto em EEG normal quanto em EEG coma. Já FM traz informações de valores de frequências em que há maior concentração de potência, e por fim o quantificador coerência informa o grau de semelhança entre o hemisfério direito e o esquerdo do cérebro. Sendo assim não foi possível afirmar qual dos quantificadores apresentou melhores resultados, visto que cada um trata-se de uma características distintas. / The EEG signal, whose information describes the electrical behavior of the cerebral cortex, although it is widely used for diagnoses, mainly of pathologies such as epilepsy, in Brazil it is still not usual to monitor the ICU environment in public hospitals. Considering this, and assuming that studies on normal EEG, registered in people without neurological problems, are scarce, the creation of a base of normal EEG registers and quantitative analysis of it is necessary so that, through the obtained results, Normal patterns can be established and through them, the identification of pathological parameters becomes more effective. In this project, an EEG database was developed, with 100 valid records from normal and healthy volunteers. In addition, from these records, the waking and closed eyes situation was analyzed under the aspect of three distinct quantifiers, being: Power Contribution Percentage (PCP), Median Frequency (FM) and Coherence, both evaluating the signal in the frequency domain. In order to obtain comparisons for the results obtained by the analysis of the normal EEG data, 128 EEG records were used in coma, with different types of etiologies and outcomes. The rhythms that presented the highest distinctions between normal and coma were Delta and Alpha, mainly for the FM quantifier. It was noted that PCP evaluated power characteristics and therefore synthesized the energy information of each brain rhythm in both normal EEG and EEG coma. Already FM brings information of values of frequencies in which there is greater concentration of power, and finally the quantifier coherence informs the degree of similarity between the right and left hemisphere of the brain. Thus, it was not possible to say which of the quantifiers presented better results, since each one is a distinct characterization. / Dissertação (Mestrado)

This Diploma thesis deals with assessment of the influence of two fundamental types of resistance welders operation on chosen power quality parameters at the point of common coupling (PCC) of the power network. The assessed parameters of power quality are the total harmonic distortion of the supply voltage, asymmetry of the supply voltage and the level of short term flicker at the point of common coupling. The assessment is based on the comparison of the results of computer simulations done in PSCad 4.2.0 with the requirements of technical standards. The outcome of this thesis is the determination of allowable limits for physical and operation parameters for the general arrangement of a power distribution network and a resistance welder that should guarantee the power quality compliance.