Reaching task performance is associated to neuromuscular junction adaptations in rats with induced diabetes mellitus

Upper limb performance is affected by diabetes mellitus (DM). Neuromuscular junction (NMJ) is a key structure to understand the relationship between performance and morphology in DM. The aim of the study was to analyze NMJ plasticity due to DM in an animal model and its relationship with the function of forelimbs in rats. Twelve Wistar rats were divided into control (C) and DM groups. Animals were trained to perform a grasping task, following procedures of habituation, shaping, and reaching task. DM was induced using streptozotocin. Forelimb neuromuscular performance for dexterity was evaluated one day before DM induction and five weeks following induction. After that, biceps, triceps, and finger flexors and extensors were removed. Connective tissue and muscle fiber cross-sectional area (CSA) were measured. NMJ was assessed by its morphometric characteristics (area, perimeter, and maximum diameter), using ImageJ software. Motor performance analyses were made using single pellet retrieval task performance test. Student's t-test was used for comparisons between groups. A significant decrease in all NMJ morphometric parameters was observed in the DM group compared with the C group. Results showed that DM generated NMJ retraction in muscles involved in a reaching task. These alterations are related to signs of muscular atrophy and to poor reaching task performance. In conclusion, induced DM caused NMJ retraction and muscular atrophy in muscles involved in reaching task performance. Induced DM caused significantly lower motor performance, especially in the final moments of evaluation, when DM compromised the tropism of the muscular tissue.

Decreased muscle strength is associated with proinflammatory cytokines but not testosterone levels in men with diabetes

The aim of this study was to compare muscle strength in male subjects with type 2 diabetes mellitus (DM2) with and without low plasma testosterone levels and assess the relationship between muscle strength, testosterone levels, and proinflammatory cytokines. Males (75) aged between 18 and 65 years were divided into 3 groups: control group that did not have diabetes and had a normal testosterone plasma level (>250 ng/dL), DnormalTT group that had DM2 with normal testosterone levels, and the DlowTT group that had DM2 and low plasma testosterone levels (<250 ng/dL). The age (means±SD) of the groups was 48.4±10, 52.6±7, and 54.6±7 years, respectively. Isokinetic concentric and isometric torque of knee flexors and extensors were analyzed by an isokinetic dynamometer. Plasma testosterone and proinflammatory cytokine levels were determined by chemiluminescence and ELISA, respectively. Glycemic control was analyzed by glycated hemoglobin (HbA1C). In general, concentric and isometric torques were lower and tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β plasma levels were higher in the groups with diabetes than in controls. There was no correlation between testosterone level and knee torques or proinflammatory cytokines. Concentric and isometric knee flexion and extension torque were negatively correlated with TNF-α, IL-6, and HbA1C. IL-6 and TNF-α were positively correlated with HbA1C. The results of this study demonstrated that muscle strength was not associated with testosterone levels in men with DM2. Low muscle strength was associated with inflammatory markers and poor glycemic control.

Effects of exercise training on atrophy gene expression in skeletal muscle of mice with chronic allergic lung inflammation

We evaluated the effects of chronic allergic airway inflammation and of treadmill training (12 weeks) of low and moderate intensity on muscle fiber cross-sectional area and mRNA levels of atrogin-1 and MuRF1 in the mouse tibialis anterior muscle. Six 4-month-old male BALB/c mice (28.5 ± 0.8 g) per group were examined: 1) control, non-sensitized and non-trained (C); 2) ovalbumin sensitized (OA, 20 µg per mouse); 3) non-sensitized and trained at 50 percent maximum speed _ low intensity (PT50 percent); 4) non-sensitized and trained at 75 percent maximum speed _ moderate intensity (PT75 percent); 5) OA-sensitized and trained at 50 percent (OA+PT50 percent), 6) OA-sensitized and trained at 75 percent (OA+PT75 percent). There was no difference in muscle fiber cross-sectional area among groups and no difference in atrogin-1 and MuRF1 expression between C and OA groups. All exercised groups showed significantly decreased expression of atrogin-1 compared to C (1.01 ± 0.2-fold): PT50 percent = 0.71 ± 0.12-fold; OA+PT50 percent = 0.74 ± 0.03-fold; PT75 percent = 0.71 ± 0.09-fold; OA+PT75 percent = 0.74 ± 0.09-fold. Similarly significant results were obtained regarding MuRF1 gene expression compared to C (1.01 ± 0.23-fold): PT50 percent = 0.53 ± 0.20-fold; OA+PT50 percent = 0.55 ± 0.11-fold; PT75 percent = 0.35 ± 0.15-fold; OA+PT75 percent = 0.37 ± 0.08-fold. A short period of OA did not induce skeletal muscle atrophy in the mouse tibialis anterior muscle and aerobic training at low and moderate intensity negatively regulates the atrophy pathway in skeletal muscle of healthy mice or mice with allergic lung inflammation.

Electrical stimulation and isokinetic training: effects on strength and neuromuscular properties of healthy young adults / Estimulação elétrica e treinamento isocinético: efeitos na força e propriedades neuromusculares de adultos jovens sadios

OBJECTIVE: To assess the effects of neuromuscular electrical stimulation (NMES) associated with an isokinetic training program in healthy young men and women. METHODS: Twenty participants (ten men, ten women; 21±1.5 years) underwent an isokinetic training program for knee extensors of both sides (three sets of ten concentric repetitions at 30°/s) twice a week for four weeks. One limb underwent only the isokinetic strength training (Ex) while the other underwent the same training but with NMES associated with each contraction (Ex+NMES). The current used for NMES was the Russian current (frequency of 2,500Hz, 50 bursts/s and pulse duration of 200µs). Isometric and isokinetic concentric extensor torque at 30°/s were evaluated. RESULTS: The groups increased their peak torque in both test procedures, with no difference between Ex and Ex+NMES. The angle of peak torque increased for the Ex limb, thus showing a change in the tension-length relationship of the muscle group tested, which did not occur for the Ex+NMES limb. There was also a decrease in acceleration time in both limbs, without any effects from NMES on this variable. CONCLUSIONS: These results showed that the association between NMES and isokinetic concentric voluntary strength training did not improve the strength gains and neuromuscular properties of voluntary strength training itself for healthy young participants of both genders.

OBJETIVO: Verificar os efeitos da estimulação elétrica neuromuscular (EENM) associada a um programa de treinamento isocinético em homens e mulheres jovens e sadios. MÉTODOS: Vinte indivíduos (dez homens, dez mulheres, 21±1,5 anos) submeteram-se a um programa de treinamento isocinético de ambos os seus extensores de joelho (três séries de dez repetições concêntricas a 30°/s) duas vezes por semana por quatro semanas. Um membro foi submetido apenas ao treinamento de força isocinético (Ex) enquanto o outro foi submetido ao mesmo treinamento, mas com EENM associada a cada contração (Ex+EENM). A corrente utilizada para a EENM foi a corrente russa (frequência de 2.500Hz, 50 bursts/s, duração de pulso de 200µs). O protocolo de avaliação incluiu o torque extensor isométrico e isocinético concêntrico a 30°/s. RESULTADOS: Os grupos aumentaram seu pico de torque em ambas as modalidades testadas, sem diferença entre Ex e Ex+EENM. O ângulo do pico de torque aumentou para o membro Ex, mostrando uma alteração da relação comprimento-tensão do grupo muscular testado, o que não aconteceu com o membro Ex+EENM. Houve também uma diminuição no tempo de aceleração de ambos os membros, sem efeito da EENM sobre este parâmetro. CONCLUSÕES: Estes resultados mostraram que a associação entre a EENM e o treinamento voluntário isocinético concêntrico não melhorou os ganhos de força e de propriedades neuromusculares do próprio treinamento de força voluntário para sujeitos jovens e sadios de ambos os gêneros.

Changes in types of muscle fibers induced by transcutaneous electrical stimulation of the diaphragm of rats

The objective of the present study was to assess the effect of transcutaneous electrical diaphragmatic stimulation (TEDS) on different types of diaphragm muscle fibers. Male Wistar rats (8-12 weeks old) were divided into 2 experimental groups (N = 8 in each group): 1) control, 2) animals submitted to TEDS [frequency = 50 Hz; T ON/T OFF (contraction/relaxation time) = 2/2 s; pulse duration = 0.4 ms, intensity = 5 mA with a 1 mA increase every 3 min for 20 min] for 7 days. After completing this treatment period, the I, IIA, IIB, and IID diaphragm muscle fibers were identified using the mATPase technique. Statistical analysis consisted of the normality, homoscedasticity and t-tests (P < 0.05). There was a 19.6 percent (P < 0.05) reduction in the number of type I fibers and a 49.7 percent increase (P < 0.05) in type IID fibers in the TEDS group compared with the control group. An important result of the present study was that electrical stimulation with surface electrodes was efficient in altering the distribution of fibers in diaphragm muscle. This therapeutic resource could be used in the treatment of respiratory muscle alterations.

Peak torque and knee kinematics during gait after eccentric isokinetic training of quadriceps in healthy subjects / O pico de torque e a cinemática do joelho durante a marcha após treino isocinético excêntrico do quadríceps em sujeitos saudáveis

OBJECTIVE: To evaluate the effects of eccentric isokinetic training on knee range of motion (ROM) of healthy subjects. METHODS: The knee extensor and flexor isokinetic peak torques and ROM of flexion/extension and varus/valgus knee movements during gait of 18 healthy men (21.7±2.2 years; 1.73±0.10m; 68.7±9.4kg; body mass index: 22.6±2kg/m²) were analyzed, before and after six weeks of bilateral eccentric isokinetic training of the knee extensors at 30º/s. RESULTS: The knee extensor torque increased in both limbs (right, from 229±54 to 304±53Nm; p<0.01; and left, from 228±59 to 311±63Nm; p<0.01), without any difference in torque gain between them. The knee flexor peak torque increased (from 114±30 to 123±22Nm; p<0.05), but the hamstrings/quadriceps (H/Q) ratio decreased (from 0.5±0.08 to 0.39±0.07; p<0.01) after the training. There were no differences in the flexion/extension and varus/valgus movements after the training, except for a small change (4°) in valgus for the left knee. CONCLUSIONS: The eccentric isokinetic training of the knee extensors increased the extensor torque and decreased the H/Q ratio, although the effect on the gait pattern seemed negligible in healthy subjects. Associated training for flexors, complementary to the extensor training, seems to be necessary for balance between knee agonists and antagonists.

OBJETIVO: Avaliar os efeitos do treino isocinético excêntrico sobre a amplitude de movimento (ADM) do joelho em sujeitos saudáveis. MÉTODOS: Foram analisados os picos de torque isocinético dos extensores e flexores do joelho e a ADM de flexo/extensão e valgo/varo, durante a marcha, de 18 homens saudáveis (21,7±2,2 anos; 1,73±0,10m; 68,7±9,4kg; índice de massa corpórea: 22,6±2kg/m²) antes e após seis semanas de treino isocinético excêntrico bilateral dos extensores do joelho a 30º/s. RESULTADOS: O torque extensor do joelho aumentou em ambos os membros, direito (de 229±54 para 304±53Nm; p<0,01) e esquerdo (de 228±59 para 311±63Nm; p<0,01) sem diferença de ganho de torque entre eles. O pico de torque flexor aumentou (de 114±30 para 123±22Nm; p<0,05), mas a razão isquiotibiais/quadríceps (I/Q) diminuiu (de 0,5±0,08 para 0,39±0,07; p<0,01) após o treino. Não houve diferença para os movimentos de flexo/extensão e valgo/varo após o treino, exceto uma pequena mudança (4°) no valgo para o joelho esquerdo. CONCLUSÕES: O treino isocinético excêntrico dos extensores do joelho aumentou o torque extensor e diminuiu a razão I/Q, entretanto o efeito sobre o padrão da marcha parece desprezível em sujeitos saudáveis. Um treino associado dos flexores, complementar ao treino dos extensores parece ser necessário para o equilíbrio entre agonistas e antagonistas do joelho.

Efeitos do alongamento ativo excêntrico dos músculos flexores do joelho na amplitude de movimento e torque / Effects of an active eccentric stretching program for the knee flexor muscles on range of motion and torque

OBJETIVO: Avaliar a amplitude de movimento (ADM) e o torque flexor e extensor do joelho após a realização de um programa de alongamento ativo excêntrico dos músculos flexores do joelho. MATERIAIS E MÉTODOS: Trinta e quatro voluntários (23 mulheres e 11 homens), 34,42±9,3 anos, realizaram um programa de alongamento ativo excêntrico dos músculos flexores do joelho na postura em pé, que consistiu de sete repetições de um minuto com 30 segundos de descanso entre as repetições. O programa de alongamento foi realizado duas vezes por semana, durante quatro semanas. A ADM de extensão e o torque flexor e extensor do joelho foram avaliados no dinamômetro isocinético pré e pós-programa de alongamento. O torque foi avaliado nos modos isométrico e isocinético concêntrico e excêntrico a 30º/s e 60º/s. RESULTADOS: Houve aumento na ADM de 53,7±13º para 30,1±16º (p=0,0001), no torque isométrico flexor de 89±32Nm para 93±33Nm (p=0,01) e extensor de 178±67Nm para 187±73Nm (p=0,006). O torque flexor concêntrico e excêntrico a 30º/s aumentou de 90±31Nm para 96±31Nm (p=0,001) e de 100±34Nm para 105±35Nm (p=0,01), respectivamente. O torque extensor concêntrico a 60º/s aumentou de 144±51Nm para 151±58Nm (p=0,02) e o excêntrico a 30º/s de 175±71Nm para 189±73Nm (p=0,01). CONCLUSÕES: O programa de alongamento proposto foi efetivo para aumentar a flexibilidade dos músculos alongados e torque dos grupos musculares agonistas (alongados) e seus antagonistas.

OBJECTIVE: To evaluate the changes in knee range of motion (ROM) and torque of knee flexor and extensor muscles after an active eccentric stretching program for the knee flexor muscles. METHODS: Thirty-four volunteers (23 women and 11 men), aged 34.42±9.3 years, performed an active eccentric stretching program for the knee flexor muscles in the standing posture, consisting of seven repetitions of one minute each, with 30 seconds of resting between them. The stretching program was performed twice a week, for four weeks. Knee extension ROM and the torque of the knee flexor and extensor muscles were evaluated using an isokinetic dynamometer before and after the stretching program. The torque was evaluated in the isometric, isokinetic concentric and eccentric modes at 30º/s and 60º/s. RESULTS: There was an increase in ROM from 53.7±13º to 30.1±16º (p=0.0001), in isometric torque of the flexors from 89±32Nm to 93±33Nm (p=0.01) and of the extensors from 178±67Nm to 187±73Nm (p=0.006). The concentric and eccentric torque of the flexors at 30º/s increased from 90±31Nm to 96±31Nm (p=0.001) and from 100±34Nm to 105±35Nm (p=0.01), respectively. The concentric torque of the extensors at 60º/s increased from 144±51Nm to 151±58Nm (p=0.02), and the eccentric torque at 30º/s increased from 175±71Nm to 189±73Nm (p=0.01). CONCLUSIONS: The stretching program proposed was effective for increasing the flexibility of the stretched muscles and the torque of the agonist (stretched) muscle groups and their antagonists.

O Efeito da crioterapia e compressão interminente no músculo lesado de ratos: uma análise morfométrica / The effect of intermittent cryotherapy and compression on muscle injuries in rats: a morphometric analysis

INTRODUÇÃO: Embora a crioterapia associada à compressão seja recomendada como tratamento imediato após lesão muscular, o efeito de sessões intermitentes desses procedimentos na área de lesão muscular secundária não é bem estabelecido. O objetivo deste estudo foi avaliar o efeito da aplicação intermitente de crioterapia e compressão (três sessões de 30 min a cada 1h30min) na área de lesão do músculo tibialis anterior direito (TAD) do rato. METODOLOGIA: A lesão muscular foi induzida por criolesão no TAD. Vinte e quatro ratos Wistar (340 ± 20g) foram divididos em quatro grupos experimentais: a) O grupo Lesão + Crioterapia (L+C) recebeu tratamentos intermitentes de crioterapia e compressão; b) O grupo Lesão + Placebo (L+P) recebeu tratamento placebo; c) O grupo Lesão (L) não foi submetido a nenhum protocolo de tratamento; e d) o grupo Crioterapia (C) que permaneceu intacto e foi submetido a tratamentos de crioterapia e compressão. Os animais foram sacrificados 24h pós-lesão, sendo os músculos seccionados em criostato e os cortes histológicos corados com Azul de Toluidina para posterior mensuração da área muscular lesada (morfometria). A análise estatística constou da ANOVA e do teste Tukey (p < 0,05). RESULTADOS: A morfometria aplicada 24 horas pós-lesão indicou redução significante da área de lesão muscular no grupo L+C (35,87 ± 4,9 por cento) quando comparado aos grupos L+P (46,4 ± 3,9 por cento; p= 0,001) e L (46,5 ± 4,1 por cento; p= 0,002). CONCLUSÃO: Três sessões de crioterapia e compressão foram eficientes na prevenção do aumento da área de lesão, enquanto somente a compressão não apresentou a mesma efetividade.

INTRODUCTION: Although cryotherapy associated with compression has been recommended as an immediate treatment for muscle injuries, the effect of intermittent sessions of these procedures in the area of secondary muscle injuries has not been clearly established. OBJECTIVE: To evaluate the effect of intermittently applying cryotherapy and compression (three 30-minute sessions at 90-minute intervals) on an injured area of the right tibialis anterior (RTA) muscle in rats. Method: An injury was induced in the RTA muscle by means of cryoinjury. Twenty-four Wistar rats (340 ± 20g) were divided into four experimental groups: a) Injury + Cryotherapy (I+C), which received intermittent cryotherapy and compression; b) Injury + Placebo (I+P), which received placebo treatment; c) Injury (I), which did not undergo any treatment protocols; and d) Cryotherapy, which remained intact and underwent cryotherapy and compression treatment. The animals were sacrificed 24 hours after the injury, and the muscles were sectioned in a cryostat. The histological sections were stained with toluidine blue for subsequent measurement of the area of the muscle injury (morphometry). The statistical analysis consisted of the ANOVA and Tukey tests (p < 0.05). RESULTS: The morphometric analysis 24 hours after the injury indicated that there had been a significant reduction in the area of the muscle injury in the I+C group (35.87 ± 4.9 percent), in comparison with the I+P group (46.4 ± 3.9 percent; p= 0.001) and the I group (46.5 ± 4.1 percent; p= 0.002). CONCLUSION: Three sessions of cryotherapy and compression were efficient in preventing an increase in the injured area, while compression alone did not achieve such effectiveness.

Pain in workers with shoulder impingement syndrome: an assessment using the DASH and McGill pain questionnaires

OBJECTIVE: This study assessed physical function and pain in male and female workers with shoulder impingement syndrome using the Brazilian Portuguese versions of the Disabilities of the Arm, Shoulder and Hand (DASH) and McGill pain questionnaires. METHODS: Twenty-seven assembly line workers (18 men and 9 women; mean age of 33.26 ± 6.49 years) in the school supply industry were evaluated. The duration of the shoulder impingement pain was 31.74 ± 32.92 months and the amount of time of the workers in this industry was 11.08 ± 6.41 years. The DASH questionnaire was used to evaluate functional status and symptoms of the upper limbs of the workers. Using the McGill Pain Questionnaire, the pain was quantified by the number of words chosen and by the pain rating index (PRI). RESULTS: The women presented higher scores (P< 0.05) than the men for both DASH overall and DASH work scores. The women chose more words (17.00 ± 2.59) than the men (13.33 ± 3.16) and also presented the highest total PRI (P< 0.05). CONCLUSIONS: The results obtained in this group of Brazilian workers with shoulder impingement identify the most commonly used descriptors of shoulder pain. Further, this study shows that females are more likely than males to refer physical disability and pain. Also, the DASH and McGill pain questionnaires are important and helpful tools in the clinical evaluation of shoulder impingement syndrome.

OBJETIVO: Este estudo avaliou função física e dor em trabalhadores com síndrome do impacto através das versões brasileiras dos questionários "Disabilities of the Arm, Shoulder and Hand" (DASH) e McGill de dor. MÉTODO: Vinte e sete trabalhadores (18 homens e 9 mulheres; idade média de 33,26 ± 6,49 anos) de uma linha de produção de uma indústria de material escolar foram avaliados. O tempo de duração de dor no ombro era de 31,74 ± 32,92 meses e o tempo de trabalho na indústria era de 11,08 ± 6,41 anos. O questionário DASH foi utilizado para avaliar o estado funcional e os sintomas dos membros superiores dos trabalhadores. Através do questionário McGill de dor, a dor foi quantificada pelo número de palavras escolhidas e pelo índice de classificação da dor (ICD). RESULTADOS: As mulheres apresentaram maiores escores (P< 0,05) que os homens para ambos os módulos do DASH. As mulheres escolheram mais palavras (17,00 ± 2,59) que os homens (13,33 ± 3,16) e também apresentaram o maior ICD total (P< 0,05). CONCLUSÃO: Os resultados obtidos neste grupo de trabalhadores brasileiros com síndrome do impacto do ombro identificam os mais comuns descritores utilizados para dor no ombro. Além disso, este estudo mostra que as mulheres estão mais propensas a relatarem incapacidade física e dor quando comparadas aos homens. Os questionários DASH e McGill de dor são ferramentas importantes e úteis na avaliação clínica da síndrome do impacto do ombro.

Cyclosporin-A does not affect skeletal muscle mass during disuse and recovery

Cyclosporin-A (CsA) is an immunosuppressive drug that acts as an inhibitor of calcineurin, a calcium phosphatase that has been suggested to play a role in skeletal muscle hypertrophy. The aim of the present study was to determine the effect of CsA administration (25 mg kg-1 day-1) on skeletal muscle mass and phenotype during disuse and recovery. Male Wistar rats received vehicle (N = 8) or CsA (N = 8) during hind limb immobilization (N = 8) and recovery (N = 8). Muscle weight (dry/wet) and cross-sectional area were evaluated to verify the effect of CsA treatment on muscle mass. Muscle phenotype was assessed by histochemistry of myosin ATPase. CsA administration during immobilization and recovery did not change muscle/body weight ratio in the soleus (SOL) or plantaris (PL). Regarding muscle phenotype, we observed a consistent slow-to-fast shift in all experimental groups (immobilized only, receiving CsA only, and immobilized receiving CsA) as compared to control in both SOL and PL (P < 0.05). During recovery, no difference was observed in SOL or PL fiber type composition between the experimental recovered group and recovered group receiving CsA compared to their respective controls. Considering the muscle/body weight ratio, CsA administration does not maximize muscle mass loss induced by immobilization. Our results also indicate that CsA fails to block skeletal muscle regrowth after disuse. The present data suggest that calcineurin inhibition by CsA modulates muscle phenotype rather than muscle mass.

Avaliação da amplitude articular do joelho: correlação entre as medidas realizadas com o goniômetro universal e no dinamômetro isocinético / Knee joint range-of-motion evaluation: correlation between measurements achieved using a universal goniometer and an isokinetic dynamometer

CONTEXTUALIZAÇÃO: O instrumento mais utilizado pelos terapeutas para mensuração da amplitude de movimento (ADM) articular é o goniômetro universal. No entanto, há carência de estudos que analisem a confiabilidade das medidas da ADM do joelho realizadas no dinamômetro isocinético. OBJETIVO: O objetivo deste estudo foi analisar a correlação entre as medidas de ADM na articulação do joelho, realizadas com o goniômetro universal e no dinamômetro isocinético. MÉTODO: Foram avaliados 38 voluntários saudáveis (27 mulheres, 11 homens), com idade de 36 ± 11 anos, com limitação mínima de 20° na ADM de extensão do joelho. No membro dominante de cada sujeito foram realizadas três mensurações da ADM do joelho com o goniômetro e três mensurações no dinamômetro. RESULTADOS: Os resultados deste estudo mostraram que há alto grau de correlação entre as medidas da ADM do joelho obtidas com o goniômetro universal e no dinamômetro isocinético (Coeficiente de Correlação de Pearson = 0,90). CONCLUSÃO: Com os procedimentos realizados, tanto o goniômetro universal como o dinamômetro isocinético podem ser utilizados para avaliação da ADM do joelho, pois ambos apresentam mensurações confiáveis.

A influencia da estimulacao eletrica funcional associada ao treinamento em esteira com suporte parcial de peso na marcha de Hemipareticos / Influence on hemiparetic patients gait abilities from electrial functional stimulation during treadmill training with partial weight support

Avaliar os efeitos do treino em esteira eletrica com suporte parcial de peso associado a estimulacao eletrica funcional na marcha de sujeitos hemiplegicos por meio da analise de variaveis espaco-temporais. Metodo: para tal proposito foi utilizado o sistema A1-B-A2,no qual A1 e A2 correspondem ao treinamento em esteira eletrica com suporte parcial de peso e B, ao mesmo treinamento associado a estimulacao eletrica funcional. participaram deste estudo dois pacientes hemiparetcos cronicos que foram submetidos a treinamento durante 45 minutos, tres vezes por semana durante 9 semanas...

Analise do torque isometrico e da atividade elétrica apos lesão muscular induzida por exercício excentrico em humanos / Analysis of isometrci torque and of the electrical activity after induced muscle damage by eccentric exercise human

Este estudo avaliou e relacionou as alteracoes funcionais domusculo quadriceps femoral apos lesao induzida pelo exercicio excentrico. O torque isometrico maximo medio desse musculo e a eletromiografia de superficie (raiz quadrada da media dos quadrados, root meam square - RMS; frequencia mediana -FM) dos musculos vasto medial obliquo(VMO) e vasto lateral(VL) foram avaliados antes, imediatamente apos e durante os 7 dias apos o exercicio excentrico. As imagens de ressonancia magnetica nuclearRMN) de tres voluntarias foram usadas para evidenciar a presenca de lesao muscular. Nove mulheres (21,7+-1,48 anos), sedentarias e saudaveis, foram avaliadas. A lesao foi induzida por meio de contracoes isocineticas excentricas. O torque isometrico maximo medio e a atividade eletrica foram mensurados por meio da contracao isometrica maxima com o joelho a 90 graus de flexao. O torque isometrico maximo medio diminiu imediatamente apos o exercicio excentrico (p<0,01), com recuperacao gradual na primeira semana. O RMS do musculo VL diminuiu imediatamente apos o exercicio excentrico (p<0,05). Por outro lado, somente o musculo VMO ocorreu aumento na FM imediatamente apos o exercicio excentrico (p<0,01). Correlacao significativa foi observada entre o torque isometrico maximo medio e a FM do musculo VMO entre o 1o. e 7o. dia apos o exercicio (r=0,32, p<0,05). Extensas areas de lesao no musculo quadriceps femoral foram identificadas pela RMN. Em conclusao, o exercicio excentrico diminuiu o torque isometrico maximo medio e alterou o sinal eletromiografico, os quais se recuperaram gradualmente na primeira semana, apesar da presenca de lesao muscular

Effect of passive stretching on the immobilized soleus muscle fiber morphology

The aim of the present study was to determine the effect of stretching applied every 3 days to the soleus muscle immobilized in the shortened position on muscle fiber morphology. Eighteen 16-week-old Wistar rats were used and divided into three groups of 6 animals each: a) the left soleus muscle was immobilized in the shortened position for 3 weeks; b) during immobilization, the soleus was stretched for 40 min every 3 days; c) the non-immobilized soleus was only stretched. Left and right soleus muscles were examined. One portion of the soleus was frozen for histology and muscle fiber area evaluation, while the other portion was used to identify the number and length of serial sarcomeres. Immobilized muscles (group A) showed a significant decrease in weight (44 ± 6 percent), length (19 ± 7 percent), serial sarcomere number (23 ± 15 percent), and fiber area (37 ± 31 percent) compared to the contralateral muscles (P < 0.05, paired Student t-test). The immobilized and stretched soleus (group B) showed a similar reduction but milder muscle fiber atrophy compared to the only immobilized group (22 ± 40 vs 37 ± 31 percent, respectively; P < 0.001, ANOVA test). Muscles submitted only to stretching (group C) significantly increased the length (5 ± 2 percent), serial sarcomere number (4 ± 4 percent), and fiber area (16 ± 44 percent) compared to the contralateral muscles (P < 0.05, paired Student t-test). In conclusion, stretching applied every 3 days to immobilized muscles did not prevent the muscle shortening, but reduced muscle atrophy. Stretching sessions induced hypertrophic effects in the control muscles. These results support the use of muscle stretching in sports and rehabilitation.

Effect of one stretch a week applied to the immobilized soleus muscle on rat muscle fiber morphology

We determined the effect of stretching applied once a week to the soleus muscle immobilized in the shortened position on muscle fiber morphology. Twenty-six male Wistar rats weighing 269 ± 26 g were divided into three groups. Group I, the left soleus was immobilized in the shortened position for 3 weeks; group II, the soleus was immobilized in the shortened position and stretched once a week for 3 weeks; group III, the soleus was submitted only to stretching once a week for 3 weeks. The medial part of the soleus muscle was frozen for histology and muscle fiber area evaluation and the lateral part was used for the determination of number and length of serial sarcomeres. Soleus muscle submitted only to immobilization showed a reduction in weight (44 ± 6 percent, P = 0.002), in serial sarcomere number (23 ± 15 percent) and in cross-sectional area of the fibers (37 ± 31 percent, P < 0.001) compared to the contralateral muscles. The muscle that was immobilized and stretched showed less muscle fiber atrophy than the muscles only immobilized (P < 0.05). Surprisingly, in the muscles submitted only to stretching, fiber area was decreased compared to the contralateral muscle (2548 ± 659 vs 2961 ± 806 µm², respectively, P < 0.05). In conclusion, stretching applied once a week for 40 min to the soleus muscle immobilized in the shortened position was not sufficient to prevent the reduction of muscle weight and of serial sarcomere number, but provided significant protection against muscle fiber atrophy. In contrast, stretching normal muscles once a week caused a reduction in muscle fiber area.

Remodelamento muscular induzido por treinamento: expressao de miosina em musculo esqueletico de rato: uma anlise qualitativa / Effects of training in muscular remodeling: myosin expression in rat skeletal muscle - a qualitative analysis

O musculo possui uma habiliade inerente de adpatacao diante de variadas condicoes, como tipo de inervacao, atuacao de hormonios, atividade contratil (treinamento), condicao de alongamento, o proprio crescimento pos-natal, entre outros. Ha grande correlacao entre a isoforma de cadeia pesada de miosina (CPM) expressa e a funcao muscular. O presente estudo teve por objetivo estudar o remodelamento muscular por meioda analise da expressao das diferentes isoformas de CPM de musculo esqueletico em ratos submetidos a treinamento fisico. A metodologia utilizada consistiu em treinamento de ratos albinos (n=10), machos, em protocolo de natacao, em um periodo de 6 horas/dia, em 3 sessoes de 2 horas, com intervalos de 30 minutos entre cadasessao, totalizando 5 dias de treinamento. Ao termino do treinamento, os animais foram sacrificados para extracao do musculo soleo. Foi feita extracao de RNA total e posterior reacao de RT-PCR utilizando oligonucleotideos iniciadores especificos para as diferentes isoformas de CPM. Tambem foi realizada, a partir de extratos proteicos do musculo retirado, a separacao eletroforetica das isiformas de CPM, utilizando SDS-PAGE com gradiente de (7 - 10 por cento). Os resultados obtidos com a tecnica de RT-PCR demonstrarm expressao de todas as isoformas de CPM, tanto em ratos sedentarios como nos treinados. Apesar de a analise nao ter sido feita de forma quantitativa, parece haver tendencia de aumento especialmente das isiformas IIa e IIx com a evolucao do treinamento. A separacao eletroforetica das isoformas mostrou que nao houve alteracao na expressao das isoformas de CPM (I, IIa, IIb e IIx) com o treinamento

Alteracoes da cronaxia, da reobase e da acomodacao no musculo esqueletico desnervado submetido a eletroestimulacao / Alterations of the chronaxie, reobase and accomodation in denervated skeletal muscle submitted to electrical stimulation

O uso da eletroestimulacao (EE) no tratamento das lesoes nervosas perifericas e controverso. Este estudo avaliou a alteracao da cronaxia, da reobase e da acomodacao no musculo tibial anterior (TA) desnervado de ratos submetidos a EE. Quatro grupos de ratos forma divididos: TA desnervado com eletrodiagnostico (ED) semanal (DSN+ED); TA desnervado com EE em dias alternados (DSN+EE+ED); TA direito desnervado (DSN); e TA inervado (INV). O eletrodiagnostico do grupo DSN+EE+ED forneceu os parametros EE (20 contracoes intensas com corrente monopolar, exponencial; periodo de pulso igual a 2x o valor da cronaxia; frequencia de 20Hz; amplitude em nivel motor; e tempo ON 3,0 s e OFF 6,0 s). Apos 4 semanas, nota-se, em todos os musculos desnervados, diminuicao na reobase, caracterizando hiperexcitabilidade muscular. A reobase foi mairo no musculo so desnervado (1+0 mA), se comparada ao DSN+ED (0,5+0mA, p=0,00006) e ao DSN+EE+ED (0,58+0,19mA, P=0,0001). A cronaxia do grupo DSN+EE+ED foi melhor (4,06+2,1ms) se comparada aos grupos DNS+ED (8,4+0,93MS,P=0006) e DSN (5,31+0,53ms, p=0,45). A acomodacao diminuiu nos grupos DSN+ED (0,75+0,42mA) e DSN+EE+ED (0,75+0,6mA), mantendo-se com valores proximos a pre-desnervacao no grupo somente desnervado (DSN 1,8+0,45mA). Concluiu-se que, embora a EE e o ED tenha atrasado a recuperacao da reobase e da acomodacao, sua utilizacao conjunta favoreceu a rcuperacao da cronaxia. Esse resultado indica o efeito benefico no tratamento do musculo desnervado

Functional changes of human quadriceps muscle injured by eccentric exercise

The present study evaluated functional changes of quadriceps muscle after injury induced by eccentric exercise. Maximal isometric torque of quadriceps and the surface electromyography (root mean square, RMS, and median frequency, MDF) of the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles were examined before, immediately after and during the first 7 days after injury. Serum creatine kinase (CK) levels and magnetic resonance imaging (MRI) were used to identify muscle injury. The subject was used as her own control and percent refers to pre-injury data. Experiments were carried out with a sedentary 23-year-old female. Injury was induced by 4 bouts of 15 maximal isokinetic eccentric contractions (angular velocity of 5º/s; range of motion from 40º to 110º of knee flexion). The isometric torque of the quadriceps (knee at 90º flexion) decreased 52 percent immediately after eccentric exercise and recovered on the 5th day. The highest reduction of RMS occurred on the 2nd day after injury in both VL (63 percent) and VMO (66 percent) and only VL recovered to the pre-injury level on the 7th day. Immediately after injury, the MDF decreased by 5 and 3 percent (VMO and VL, respectively) and recovered one day later. Serum CK levels increased by 109 percent on the 2nd day and were still increased by 32 percent on the 7th day. MRI showed large areas of injury especially in the deep region of quadriceps. In conclusion, eccentric exercise decreased the isometric torque and electromyographic signals of quadriceps muscle, which were recovered in one week, despite the muscle regeneration signals

Alteracoes osseas associadas a traumas musculares periodicos / Changes in bone associated to periodic muscle trauma

O objetivo do prosente trabalho foi avaliar a resposta do tecido osseo a traumas musculares periodicos. O trama muscular foi produzido de forma nao-invasiva por um equipamento que libera carga sobre a superficie muscular. Os animais foram divididos aleatoriamente em 2 grupos experimentais: o primeiro foi subemtido a 4 traumas periodicos e avaliacao 7 dias apos (n=5) e o grupo controle nao foi traumatizado (n=5).O trauma foi aplicado na regiao anterior do ventre do musculo tibialis anterior (TA) direito. apos os traumas, alem das tibias direita e esquerda, os musculos TAs direito e esquerdo de ambos os grupos foram analizados. A pata contralateral dos animais do grupo traumatizado foi mantida intacta. apos o sacrificio dos animais, as tibias forma submetidas as seguintes analises. resistencia ossea, peso das cinzas, volume osseo e densidade mineral ossea. as tibias traumatizadas periodicamente apresenta maiores valores de forca maxima ate ate o ponto de fratura ossea quando comparadas as contralaterais (71,78+14,32 N vs. 49,19+17,51 N, respectivamente, p,< 0,03),indicando aumento da resistencia ossea. A analise dos parametro fisicos mostrou qu o peso das cinzas das tibias traumatizadas foi maior que o dascontralaterais intactas (0,313+0,01 vs. 0,276+0,03 g, respectivamente, p= 0,002),tambem quando comprados ao grupo controle (0,313+0,01 g vs. 0,24+0,02 g, respectivamente, p=0,003) No entanto, nao foiram observadas alteracoes nos valores do volume osseo e da densidade mineral ossea entre as tibias traumatizadas e controlaterais do grupo traumatizado periodicamente e entre as tibias de ambos os grupos experimentais. conclusoes. Ccontusoes muscular periodicas promovem alteracoes significativas no conteudo mineral osseo e na resistencia ossea, sem causar mudancas na densidade mineral ossea

A new model for the immobilization of the rat hind limb

An alternative device for the immobilization of the hind limb of the rat was developed to study the effects of chronic disuse on the soleus and tibialis anterior muscles, maintained for 3 weeks in the shortening and the stretching positions, respectively. The proposed device is made of steel mesh and cotton materials, and has some advantages when compared to cast or plaster cast: it is cheaper, lighter (12 g or 4 percent of the body weight of the rat) and the same unit can be easily adjusted and used several times in the same animal or in animals of similar size. Immobilization is also useful to restrain the movements of the hip, knee, and ankle joints. Male rats (291 ± 35 g and aged 14 ± 2 weeks) were used to develop and test the model. The soleus muscle of 18 rats was maintained in a shortened position for 21 consecutive days and lost 19 ± 7 percent of its length (P = 0.008) and 44 ± 6 percent of its weight (P = 0.002) compared to the contralateral intact muscle. No difference (P = 0.67) was found in the stretched tibialis anterior of the same hind limb when compared to the contralateral muscle. No ulcer, sore or foot swelling was observed in the animals. Immobilization was effective in producing chronic muscle disuse in the hind limbs of rats and is an acceptable alternative to the traditional methods of immobilization such as cast or plaster cast