Neuromuscular compartmentalization of the vastus medialis muscle: comparison of the activity of the vastus medialis obliquus and the vastus medialis longus by high density electromyography / Compartimentación neuromuscular del músculo vasto medial: comparación de la actividad del vasto medial oblicuo y del vasto medial largo mediante electromiografía de alta densidad

SUMMARY: Anatomical studies describe the vastus medialis (VM) as being subdivided into two morphologically distinct components, the vastus medialis obliquus (VMO) and the vastus medialis longus (VML). However, there are discrepancies regarding the functional differentiation of these components. The aim of this study was to compare the levels of activation of the VMO and the VML by high density surface electromyography. Twelve healthy young women (age: 21.4 ± 2.0 years; weight: 58.1 ± 7.5 kg; height: 1.6 ± 0.1 m), performed an open kinetic chain knee exercise during which the EMG activity of the VMO and the VML was recorded with two- dimensional matrices of 32 surface electrodes. The exercises were performed with three levels of resistance (5, 10 and 15 % of the body weight (BW)), considering three phases: concentric, isometric and excentric. In the isometric phase the VMO had greater activation than the VML with the three levels of resistance (p<0.05). In the excentric phase, the VMO also showed greater activation than the VML with the 10 and 15 % BW resistance levels, while in the concentric phase, the VMO showed greater activity than the VML with only the 15 % BW resistance. The results indicated significant differences in the activation level of the two components of the VM. This bears importance in the development of exercises intended to achieve a greater or more selective activation of the VMO. In the sample subjected to evaluation, the EMG recordings describe a greater activation of the VMO in comparison to the VML, which is more important in the isometric and excentric phases of the flexion/extension of the knee in an open kinetic chain. These findings suggest a functional compartmentalization of the VM.

RESUMEN: Los estudios anatómicos describen que el músculo vasto medial (VM) se subdivide en dos componentes morfológicamente distintos, el vasto medial obliquus (VMO) y el vasto medial largo (VML). Sin embargo, existen discrepancias con respecto a la diferenciación funcional de estos componentes. El objetivo de este estudio fue comparar los niveles de activación del VMO y el VML mediante electromiografía de superficie de alta densidad. Doce mujeres jóvenes sanas (edad: 21,4 ± 2,0 años; peso: 58,1 ± 7,5 kg; altura: 1,6 ± 0,1 m), realizaron un ejercicio de rodilla de cadena cinética abierta durante el cual se registró la actividad EMG de la VMO y la VML con dos matrices dimensionales de 32 electrodos de superficie. Los ejercicios se realizaron con tres niveles de resistencia (5, 10 y 15% del peso corporal (PC)), considerando tres fases: concéntrica, isométrica y excéntrica. En la fase isométrica el VMO tuvo mayor activación que el VML con los tres niveles de resistencia (p <0,05). En la fase excéntrica, el VMO también mostró mayor activación que el VML con los niveles de resistencia de 10 y 15% BW, mientras que en la fase concéntrica, el VMO mostró mayor actividad que el VML con solo el 15 % de resistencia al BW. Los resultados indicaron diferencias significativas en el nivel de activación de los dos componentes de la VM. Esto tiene importancia en el desarrollo de ejercicios destinados a lograr una activación mayor o más selectiva del VMO. En la muestra sometida a evaluación, los registros EMG describen una mayor activación del VMO en comparación con el VML, que es más importante en las fases isométrica y excéntrica de la flexión / extensión de la rodilla en cadena cinética abierta. Estos hallazgos sugieren una compartimentación funcional de la VM.

Concentración de bupivacaína y preservación de fuerza de cuádriceps en bloqueo femoral para artroplastía total de rodilla / Bupivacaine concentration and quadriceps strength preservation in femoral nerve block for total

INTRODUCTION: The commonly used concentrations of local anesthetics (LA) for femoral nerve block (FNB) cause a significant decrease in the quadriceps strength (QS), limiting physiotherapy and determining a risk factor for patient's falls. The use of more dilute solutions could determine the preservation of motor function without impairing analgesia. METHODS: Five patients scheduled for total knee arthroplasty (TKA) received a preoperative FNB with 20 mL of bupivacaine in decreasing concentrations (0.0875%, 0.075%, 0.0625%, 0.050%, 0.0375%). Sensory block to cold in the anterior knee region, QS, surface electromyography (SEMG) of vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) plus were recorded before and 30 minutes after the blockage. Posteriorly, the clinical data of 20 patients who underwent TKA and received a continuous femoral nerve block (CFNB) with bupivacaine in the most dilute concentration that granted sensory blockade and significantly preserved the QS in the previous analysis were retrospectively analyzed. Postoperative pain at 24 and 48 hours, morphine consumption at 24 hours, the ability to successfully perform physiotherapy on the first postoperative day (POD) and reports of falls were rescued from the patients' files. Finally, seventy-five patients that underwent TKA during 2018 who received a CFNB with a similar dilution, but using levobupivacaine, were also retrospectively analyzed. Postoperative pain, need for advanced rescue analgesia, ability to perform physiotherapy, CFNB related complications and reports of patients falls during the first 72 hours post-surgery were obtained. RESULTS: Biomechanical study: of the 5 concentrations analyzed, either 0.050% or 0.0375% bupivacaine were adequate producing sensory block and preserving 94% and 100% of the basal QS, respectively. With both concentrations, the SEMG showed a similar range of activation with respect to baseline values. Bupivacaine case series: Twenty patients undergoing TKA received a 5-8 mL/hr infusion of 0.037% bupivacaine. The average consumption of morphine at 24 hours was 3.9 (3.6) mg. The median [IQR] of dynamic postoperative pain at 24 and 48 hours was 3 [1-4] and 3 [2-5]. All patients had adequate active joint ranges at 24 hours and physiotherapy was not limited by significant motor block. No falls were reported during the stay. Levobupivacaine case series: seventy-five patients undergoing TKA received a 5-8 mL/hr infusion of 0.037% levobupivacaine. The median [IQR] of at rest (R) and dynamic (D) postoperative pain at 24, 48 and 72 hours were R24: 0 [0-3]; D24: 3 [1-5]; R48: 0 [0-2]; D48: 3 [1.5-5]; R72: 0 [0-1]; D72: 3 [1-4]. 21% of patients required adding a PCA mode to the CFNB and a 7% a morphine PCA. On POD 1, 4% of patients were not able to adequately perform rehabilitation. On POD 2 and 3, all patients had adequate active joint ranges and physiotherapy was not limited by significant motor block. There were also no falls during hospitalization. CONCLUSIONS: The use of diluted solutions of bupivacaine and levobupivacaine for CFNB may represent a good alternative for TKA postoperative analgesia while avoiding significant quadriceps paresis. Additional studies are necessary to determine the ideal concentration and administration regimen to then compare with other quadriceps sparing analgesic alternatives.

INTRODUCCIÓN: Las concentraciones habituales de anestésicos locales (AL) utilizadas para el bloqueo del nervio femoral (BNF) provocan una disminución significativa de la fuerza del cuádriceps (FC), limitando la fisioterapia y constituyendo un factor de riesgo de caídas de pacientes. El uso de soluciones más diluidas podría determinar preservación de la función motora sin perjudicar la analgesia. MÉTODOS: Cinco pacientes programados para artroplastía total de rodilla (ATR) recibieron un BNF preoperatorio con 20 mL de bupivacaína en concentraciones decrecientes (0,0875%, 0,075%, 0,0625%, 0,050%, 0,0375%). Se registró la FC, electromiografía de superficie (EMGS) de vasto lateral (VL), vasto medial (VM) y recto femoral (RF) y el bloqueo sensitivo al frío antes y 30 minutos después del bloqueo. Posteriormente, se analizó retrospectivamente 20 casos sometidos a ATR que recibieron un bloqueo continuo del nervio femoral (BCNF) con bupivacaína en la concentración más diluida que otorgó bloqueo sensitivo y preservó significativamente la fuerza basal del cuádriceps durante el análisis anterior. El dolor postoperatorio a las 24 y 48 horas, el consumo de morfina las primeras 24 horas, la capacidad de realizar con éxito la fisioterapia el primer día postoperatorio (DPO) y reporte de caídas fueron rescatados de los expedientes. Por último, también se analizó retrospectivamente un grupo de 75 pacientes sometidos a ATR durante el 2018 y que recibieron un BCNF con una dilución similar, pero de levobupivacaína. Se obtuvieron datos de dolor, requerimientos de rescate analgésico, capacidad de realizar rehabilitación, complicaciones del BCNF y reporte de caídas durante las primeras 72 horas postoperatorias. RESULTADOS: Estudio biomecánico: de las 5 concentraciones analizadas, tanto bupivacaína 0,05% como 0,0375% produjeron adecuado bloqueo sensorial preservando el 94% y el 100% de la FC, respectivamente. Con ambas concentraciones la EMGS mostró similar rango de activación respecto a valores basales. Serie de casos con bupivacaína: veinte pacientes sometidos a ATR recibieron una infusión de bupivacaína 0,037% a 5-8 mL/h. El consumo promedio de morfina a las 24 horas fue 3,9 (3,6) mg. La mediana [RIC] del dolor dinámico postoperatorio a las 24 y 48 horas fue 3 [1-4] y 3 [2-5]. Todos los pacientes tuvieron rangos articulares activos adecuados a las 24 horas y la fisioterapia no fue limitada por bloqueo motor significativo. No se registraron caídas durante la hospitalización. Serie de casos levobupivacaína: setenta y cinco pacientes sometidos a ATR recibieron una infusión de levobupivacaína 0,037% a 5-8 mL/h. La mediana [RIC] de dolor postoperatorio en reposo (R) y dinámico (D) a las 24, 48 y 72 horas fue R24: 0 [0-3]; D24: 3 [1-5]; R48: 0 [0-2]; D48: 3 [1.5-5]; R72: 0 [0-1]; D72: 3 [1-4]. Un 21% requirió agregar modo PCA al BCNF y 7% una PCA de morfina. En DPO 1, un 4% de pacientes no pudo realizar adecuadamente la rehabilitación. En DPO 2 y 3 todos los pacientes tuvieron rangos articulares activos adecuados y fisioterapia no fue limitada por bloqueo motor significativo. Tampoco se registraron caídas durante la hospitalización. CONCLUSIONES: El uso de soluciones diluidas de bupivacaína y levobupivacaína en BCNF podría representar una buena opción para analgesia postoperatoria en ATR evitando la paresia significativa del cuádriceps. Estudios adicionales son necesarios para determinar la concentración y régimen de administración ideal para luego comparar con otras alternativas analgésicas preservantes del cuádriceps.

Effects of training volume on lower-body muscle strength in untrained young men: a contralateral control study

The purpose of this study was to examine the effects of training volume (1 vs. 3 sets) on lower-body muscle strength in untrained young men. Methodsː Eighteen untrained young men were recruited and their legs were trained with 1 or 3 sets (in a contralateral design) for 6 weeks, using a knee extension machine. Isokinetic peak torque and one repetition maximum (1RM) were assessed at pre- and post-training. Resultsː There was a similar improvement in the 1RM strength (1SET: +14.8% vs. 3SET: 16.3%, P > 0.05) and peak torque (1SET: +8.1% vs. 3SET: 9.3%, P > 0.05) for both conditions from pre- to post-training. The effect size (ES) for the change in 1RM was moderate for both conditions (1SET: 1.39 vs. 3SET: 1.41), and peak torque was trivial and small for 1SET (0.47) and 3SET (0.55), respectively. Additionally, there were no significant (P > 0.05) differences in the dietary intakes from pre- to post-training. Conclusionsː Our results indicate that 1 set is as effective as 3 sets for increasing lower-body muscle strength after a short-term RT period (6 weeks) in untrained young men.(AU)

Time to task failure of the contralateral untrained limb after high load-low repetition eccentric and low load-high repetition resistance training

Abstract Aims: Cross-training is the process whereby training of one limb gives rise to enhancements in the performance of the opposite, untrained limb and may be dependent on type of muscle contractions performed. The aim of this study was to investigate whether unilateral resistance training using eccentric contraction is more effective than concentric resistance training to improve time to task failure in the contralateral untrained limb. Methods:Subjects completed 12 weeks of resistance training consisting of 36 sessions, using unilateral leg exercise. Sustained isometric knee extension performed at 50% of maxmal force until task failure for the contralateral untrained leg. Surface electromyography (EMG) signals were simultaneously recorded from contralateral untrained quadriceps (vastusmedialis, rectus femoris, and vastuslateralis). Results: Time to task failure of the contralateraluntrained leg and associated EMG activitiessignificantly increased after 12 weeks ofunilateral resistance training(p<0.05). However, percent increase in time to task failure and EMG amplitude after eccentric resistance training was significantly higher than concentric resistance training (p<0.05). Conclusion: This study concluded that unilateral eccentric resistancetraining is superior to concentric resistance training to increase time to task failure in the contralateral untrained limb.(AU)

Delayed effect of Kinesio Taping on neuromuscular performance, balance, and lower limb function in healthy individuals: a randomized controlled trial

ABSTRACT Background Kinesio Taping (KT) is an elastic bandage that aims to improve neuromuscular performance, although there is no consensus as to its benefits. Objective To analyze the immediate and delayed effects of KT on the neuromuscular performance of the femoral quadriceps, on balance, and lower limb function in healthy subjects. Method This is a randomized controlled trial. Thirty-six women with a mean age of 22.2±3.6 years and BMI of 22.5±2.3 Kg/m2 were divided into three groups: control, with ten minutes of rest (control, n=12), application of Kinesio Taping without tension (placebo, n=12) and with tension (KT, n=12) on the quadriceps. The primary outcome was isokinetic performance, while secondary outcomes were the single-hop test, one-footed static balance, and electromyographic activity. The evaluations were carried out in five stages: 1) before application of KT, 2) immediately after the application of KT, 3) after 24h, 4) after 48h, and 5) after 72h. Mixed ANOVA was used to determine differences between groups. Results There was no change in one-footed static balance, electromyographic activity of the VL in the lower limb function, nor in isokinetic performance between groups. Conclusion KT promotes neither immediate nor delayed changes in neuromuscular performance of the femoral quadriceps in healthy women.

Skinfold thickness affects the isometric knee extension torque evoked by Neuromuscular Electrical Stimulation

BACKGROUND: Subcutaneous adipose tissue may influence the transmission of electrical stimuli through to the skin, thus affecting both evoked torque and comfort perception associated with neuromuscular electrical stimulation (NMES). This could seriously affect the effectiveness of NMES for either rehabilitation or sports purposes. OBJECTIVE: To investigate the effects of skinfold thickness (SFT) on maximal NMES current intensity, NMES-evoked torque, and NMES-induced discomfort. METHOD: First, we compared NMES current intensity, NMES-induced discomfort, and NMES-evoked torque between two subgroups of subjects with thicker (n=10; 20.7 mm) vs. thinner (n=10; 29.4 mm) SFT. Second, we correlated SFT to NMES current intensity, NMES-induced discomfort, and NMES-evoked knee extension torque in 20 healthy women. The NMES-evoked torque was normalized to the maximal voluntary contraction (MVC) torque. The discomfort induced by NMES was assessed with a visual analog scale (VAS). RESULTS: NMES-evoked torque was 27.5% lower in subjects with thicker SFT (p=0.01) while maximal current intensity was 24.2% lower in subjects with thinner SFT (p=0.01). A positive correlation was found between current intensity and SFT (r=0.540, p=0.017). A negative correlation was found between NMES-evoked torque and SFT (r=-0.563, p=0.012). No significant correlation was observed between discomfort scores and SFT (rs=0.15, p=0.53). CONCLUSION: These results suggest that the amount of subcutaneous adipose tissue (as reflected by skinfold thickness) affected NMES current intensity and NMES-evoked torque, but had no effect on discomfort perception. Our findings may help physical therapists to better understand the impact of SFT on NMES and to design more rational stimulation strategies.

Neural adaptations in isometric contractions with EMG and force biofeedback

This study aimed to evaluate the quadriceps femoris neural adaptations during isometric contractions using force and electromyogram (EMG) signals as visual biofeedback. Forty-two participants were randomly assigned to three groups: EMG group, tested with EMG biofeedback; Force group, tested with force biofeedback; and Control group, tested without biofeedback. Evaluations were performed pre (baseline) and post-tests to determine the maximum force and EMG amplitude during maximal voluntary isometric contraction (MVIC). The tests consisted of series of MVICs in which the participants were encouraged to surpass the force or EMG thresholds determined at baseline. The vastus lateralis EMG amplitude and knee extensor force increased significantly in all groups when compared the baseline and post-test evaluations values ​​(p < .05). EMG percentage gain was significantly different between Force and Control groups (p < .01), while force percentage gain was not different between groups. Force biofeedback was more effective in producing neural adaptations.

Este estudo avaliou as adaptações neurais do quadríceps durante contrações isométricas usando os sinais de força e eletromiografia (EMG) como biofeedback. Quarenta e dois sujeitos foram distribuídos em três grupos: EMG, testado com biofeedback da EMG; Força, testado com biofeedback de força; e Controle, testado sem biofeedback. As avaliações foram realizadas pré/pós-testes para determinar a máxima força e amplitude EMG durante contrações isométricas voluntárias máximas (CIVM). Os testes consistiram em séries de CIVM onde os sujeitos foram encorajados a ultrapassar os limiares de força e EMG inicialmente determinados. A amplitude EMG do vasto lateral e a força extensora do joelho aumentaram significativamente em todos os grupos quando comparadas as avaliações pré e pós-testes (p < 0,05). A porcentagem de ganho EMG foi significativamente diferente entre os grupos Força e Controle (p < 0,01), enquanto que a porcentagem de ganho da força não foi diferente entre os grupos. O biofeedback de força foi mais efetivo em produzir adaptações neurais.

Este estudio evaluó las adaptaciones neurales de cuádriceps durante contracciones isométricas usando los signos de fuerza y ​​electromiografía (EMG) como biofeedback. Cuarenta y dos sujetos fueron divididos en tres grupos: EMG, probado con biofeedback EMG; Fuerza, probado con biofeedback de fuerza; y control, probado sin biofeedback. Las avaluaciones se realizaron pre/post pruebas para determinar la máxima fuerza y amplitud EMG durante contracciones isométricas voluntarias máximas (CIVM). Las pruebas consistieron en series de CIVM en que los sujetos fueron encorajados a cruzar el umbral de fuerza y EMG ​​ inicialmente determinados. La amplitud EMG del vasto lateral y fuerza de los extensores de la rodilla aumentó significativamente en todos los grupos al comparar las avaluaciones pre y post pruebas (p < 0,05). El porcentaje de ganancia EMG fue significativamente diferente entre los grupos Fuerza y ​​control (p < 0,01), mientras que el porcentaje de aumento de la fuerza no fue diferente entre los grupos. Biofeedback de fuerza fue más eficaz en producir adaptaciones neurales.

Muscle strength analysis of hip and knee stabilizers in individuals with Patellofemoral Pain Syndrome / Análisis de la fuerza muscular de los estabilizadores del cuadril y de la rodilla en sujetos con Síndrome de Dolor Patelofemoral / Análise da força muscular dos estabilizadores do quadril e joelho em indivíduos com Síndrome da Dor Femoropatelar

The Patellofemoral Pain Syndrome is one of the most common disorders of the knee, characterized by pain in the frontal part of the knee, which is worsened by activities that increase compressive forces on the joint. Alterations in the muscle strength of the quadriceps and hip stabilizer muscles can change patellar biomechanics, increasing joint stress and exacerbating pain symptoms. The aim of the study was to compare the strength of the hip and knee stabilizing muscles of women without and with Patellofemoral Pain Syndrome. The study included 45 women, 20 volunteers without the syndrome and 25 with Patellofemoral Pain Syndrome. Using an isometric dynamometer, the strength of the knee flexors and extensors, hip abductors and adductors, hip external rotators, medial rotators, hip flexors and hip extensors was evaluated. Women with Patellofemoral Pain Syndrome had 22% less strength of the internal rotators and 23% less strength of the knee extensors compared to healthy ones. As for the other muscle groups assessed, no differences were found. Therefore, the present study emphasizes that the quadriceps muscles are still the most affected muscle in individuals with the Patellofemoral Pain Syndrome.

El Síndrome de Dolor Patelofemoral es uno de los trastornos más frecuentes de la rodilla, caracterizado por dolor anterior en la rodilla, que se agrava con actividades que aumentan las fuerzas compresivas en la articulación. Alteraciones en el estándar de fuerza muscular del cuádriceps o de la musculatura estabilizadora del cuadril podrían cambiar la biomecánica de la articulación patelofemoral y así aumentar el estrés articular y exacerbar los síntomas de dolor. El objetivo de eso estudio fue relacionar la fuerza de la musculatura del cuadril y de la rodilla en mujeres con y sin el síndrome. Eso estudio incluyó 45 voluntarias, 20 sin y 25 con el Síndrome de Dolor Patelofemoral. La fuerza isométrica de los músculos flexores y extensores de la rodilla, abductores, aductores, flexores, extensores, rotadores laterales y mediales del cuadril fue evaluada por una célula de carga ajustada. Mujeres con el Síndrome de Dolor Patelofemoral presentaron reducción del 22% de la fuerza de los rotadores mediales de cuadril y un 23% de los extensores de la rodilla, cuando comparadas con las sin el Síndrome de Dolor Patelofemoral. No fueron observadas diferencias en la fuerza isométrica entre los otros grupos musculares. Por lo tanto, los datos de eso trabajo resaltan que la musculatura quadricipital y los rotadores mediales del cuadril son los más comprometidos en sujetos con el Síndrome de Dolor Patelofemoral.

A Síndrome da Dor Femoropatelar é uma das desordens mais frequentes do joelho, caracterizada por dor anterior no joelho, que se agrava com atividades que aumentam as forças compressivas na articulação. Alterações no padrão de força muscular do quadríceps ou da musculatura estabilizadora do quadril poderiam alterar a biomecânica da articulação femoropatelar e, assim, aumentar o estresse articular e exacerbar sintomas de dor. O objetivo deste estudo foi comparar a força da musculatura de quadril e joelho em mulheres com e sem tal síndrome. Participaram deste estudo 45 voluntárias, sendo 20 sem e 25 com a Síndrome da Dor Femoropatelar. A força isométrica dos músculos flexores e extensores de joelho, abdutores, adutores, flexores, extensores, rotadores laterais e mediais do quadril foi avaliada por uma célula de carga adaptada. Mulheres com Síndrome da Dor Femoropatelar apresentaram redução de 22% da força dos rotadores mediais de quadril e 23% dos extensores de joelho, em comparação àquelas sem a Síndrome da Dor Femoropatelar. Não foram observadas diferenças na força isométrica entre os outros grupos musculares. Portanto, os dados deste trabalho reforçam que a musculatura quadricipital e os rotadores mediais do quadril são os mais comprometidos em indivíduos com Síndrome da Dor Femoropatelar.

Exploratory study of electromyographic behavior of the vastus medialis and vastus lateralis at neuromuscular fatigue onset / Estudo exploratório do comportamento eletromiográfico do músculo vasto medial e vasto lateral no início da fadiga neuromuscular / Estudio exploratorio de la conducta electromiográfica del vasto medial y vasto lateral en la aparición de fatiga neuromuscular

This study aimed to determine and analyze the neuromuscular fatigue onset by median frequency (MDF) and the root mean square (RMS) behavior of an electromyographic signal (EMG). Eighteen healthy men with no prior knee problems initially performed three maximum voluntary isometric contractions (MVIC). After two days of MVIC test, participants performed a fatiguing protocol in which they performed submaximal knee-extension contractions at 20% and 70% MVIC held to exhaustion. The MDF and RMS values from the EMG signals were recorded from the vastus medialis (VM) and the vastus lateralis (VL). Analysis of the MDF and RMS behavior enabled identification of neuromuscular fatigue onset for VM and VL muscles in 20% and 70% loads. Alterations between the VM and VL in the neuromuscular fatigue onset, at 20% and 70% MVIC, were not significant. These findings suggest that the methodology proposal was capable of indicating minute differences sensible to alterations in the EMG signals, allowing identification of the moment when the MDF and the RMS showed significant changes in behavior. The methodology used was also a viable one for describing and identifying the neuromuscular fatigue onset by means of the analysis of EMG signals...

Este estudo teve como objetivo determinar e analisar o início da fadiga neuromuscular pelo comportamento do sinal de eletromiográfico (EMG) da frequência mediana (FM) e do root mean square (RMS). Dezoito homens saudáveis, sem problemas no joelho, realizaram inicialmente três contrações isométricas voluntárias máximas (CVMs). Após dois dias de CVM os sujeitos realizaram um protocolo de fadiga em que realizaram contrações submáximas de extensão do joelho em 20% e 70% da CVM até a exaustão. Os valores dos sinais de FM e RMS foram registrados a partir do vasto medial (VM) e vasto lateral (VL). A análise do comportamento da FM e RMS permitiu a identificação do início da fadiga neuromuscular para os músculos VM e VL em 20% e 70% da carga máxima. Alterações entre o VM e VL no início da fadiga neuromuscular, com 20% e 70% do MVIC, não foram significativas. Estes resultados sugerem que a metodologia proposta foi capaz de indicar diferenças mínimas sensíveis a alterações nos sinais EMG, permitindo a identificação do momento em que a FM e o RMS apresentaram mudanças significativas no seu comportamento. A metodologia utilizada também foi viável para descrever e identificar o aparecimento da fadiga neuromuscular por meio de análise de sinais de EMG...

Este estudio tieve como objetivo determinar y analizar la aparición de fatiga neuromuscular por la frecuencia media (FM) y la media de la raíz cuadrada (RMS) de lo señal electromiográfico (EMG). Dieciocho hombres saludables que no tienen problemas de rodilla previas inicialmente realizaron tres contracciones máximas voluntarias (CVM). Después de dos días de CVM los sujetos realizaron un protocolo de fatiga en la que se presentaron submáximas de extensión de rodilla en 20% y el 70% CVM hasta el agotamiento. Los valores de FM y RMS de las señales EMG se registraron desde el vasto medial (VM) y el vasto lateral (VL). Análisis del comportamiento de FM y RMS activado identificación de inicio fatiga neuromuscular para VM y músculos VL y 20% y el 70 % de la carga maxima. Las alteraciones entre el VM y VL en el inicio de la fatiga neuromuscular, en el 20% y el 70% de la CVM, no fueron significativas. Estos hallazgos sugieren que la propuesta de metodología fue capaz de indicar las diferencias minutos sensibles a las alteraciones en las señales de EMG, que permitan identificar el momento en que el FM y el RMS mostraron cambios significativos en el comportamiento. La metodología utilizada fue también una opción viable para la descripción y la identificación de la aparición de fatiga neuromuscular por medio del análisis de las señales de EMG...

The influence of stimulus phase duration on discomfort and electrically induced torque of quadriceps femoris

BACKGROUND: Although a number of studies have compared the influence of different electrical pulse parameters on maximum electrically induced torque (MEIT) and discomfort, the role of phase duration has been poorly investigated. OBJECTIVE: To examine the variation in muscle torque and discomfort produced when electrically stimulating quadriceps femoris using pulsed current with three different phase durations in order to establish whether there are any advantages or disadvantages in varying the phase duration over the range examined. METHOD: This is a two repeated-measures, within-subject study conducted in a research laboratory. The study was divided into 2 parts with 19 healthy young adults in each part.In part 1, MEIT was determined for each phase duration (400, 700, and 1000 µs), using a biphasic pulsed current at a frequency of 50 Hz. In part 2, stimulus amplitude was increased until the contractions reached 40% of maximum voluntary isometric contraction (MVIC) and the associated discomfort produced by each phase duration was measured. RESULTS: In part 1 of the study, we found that the average MEITs generated with each phase duration (400, 700, and 1000 µs) were 55.0, 56.3, and 58.0% of MVIC respectively, but the differences were not statistically significant (p=.45). In part 2, we found a statistically significant increase in discomfort over the same range of phase durations. The results indicate that, for a given level of torque production, discomfort increases with increasing phase duration (p=.008). CONCLUSIONS: Greater muscle torque cannot be produced by increasing the stimulus phase duration over the range examined. Greater discomfort is produced by increasing the stimulus phase duration. .

Análise da reprodutibilidade de parâmetros no domínio da frequência do sinal EMG utilizados na caracterização da fadiga muscular localizada / Analysis of reliability of EMG signal frequency domain parameters used in the characterization of localized muscle fatigue

O objetivo deste estudo foi analisar a reprodutibilidade de parâmetros no domínio da frequência do sinal eletromiográfico (EMG) utilizados na caracterização da fadiga muscular localizada. Quinze sujeitos do sexo masculino foram submetidos a um teste de fadiga baseado na extensão isométrica de joelho, sendo realizados em três momentos distintos com intervalos de sete dias. Para avaliar a reprodutibilidade dos dados entres os testes calculou-se o coeficiente de correlação intraclasse (CCI) para a frequência mediana (Fmed) no tempo total de exercício (FmedT), para a Fmed obtida a cada 10% do tempo de exercício (Fmed10%) e para as potências das bandas de frequência, obtidas da divisão do espectro de potência a cada 20 Hz. Os resultados demonstraram: (1) boa reprodutibilidade para a FmedT; (2) boa reprodutibilidade para a Fmed10%; e (3) maior variação no sinal EMG nas bandas de 20 a 120 Hz, no qual se destacam as bandas de 20-40 Hz e de 40-60 Hz, demonstrando maior sensibilidade ao processo de fadiga muscular. Conclui-se que a Fmed é uma variável que apresenta boa reprodutibilidade e que a análise fragmentada do espectro de potência, por meio das bandas de frequência, demonstrou-se sensível as variações que ocorrem no sinal EMG durante a instalação do processo de fadiga, tendo potencial para se tornar um novo método para a caracterização da fadiga muscular localizada.

The aim of this study was to analyze the reproducibility of the electromyography signal's parameters (EMG) in the frequency domain used in the characterization of localized muscle fatigue. Fifteen male subjects underwent a fatigue test based on isometric knee extension, being held at three different times at intervals of seven days. To assess the reproducibility of data between the tests we calculated the correlation coefficient (ICC) for the median frequency (MF) in total exercise time (MF T), MF obtained for every 10% of exercise time (MF10%) and the powers of the frequency bands obtained by dividing the power spectrum at windows of 20 Hz. The results showed: (1) excellent reproducibility for MF T, (2) good reproducibility for MF10%, and (3) greater variation in the signal EMG bands from 20 to 120 Hz, especially at the bands of 20-40 Hz and 40-60 Hz, which showed greater sensitivity to the process of muscle fatigue. We conclude that the MF is a variable that shows good reproducibility and that the fragmented analysis of the power spectrum, by means of frequency bands, showed that significant variations occur in the EMG signal during the installation of the fatigue process, having potential to become a new method for the characterization of localized muscle fatigue.

Anatomic study of the portions long and oblique of the vastus lateralis and vastus muscles: review article

Although not mentioned directly in the classical anatomical literature, the vastus lateralis and vastus medialis, which make up the quadriceps femoris muscle, show variations in their anatomical structures due to the presence of long and oblique portions receiving the designation of vastus lateralis longus, vastus lateralis obliques to the vastus lateralis and vastus medialis oblique and vastus long, for the vastus medialis. The aim of this paper is to review the scientific literature regarding the presence of long and oblique portions of the broad medial and lateral portions recognize these as integral parts, anatomically, the quadriceps femoris. To this end, we used published articles in magazines and journals, located through Medline, and Lilacs Excerpa Medica, and the Portal Capes, with the key words: quadriceps, vastus medialis, vastus lateralis, vastus medialis longus, vastus medialis oblique , vastus lateralis longus and vastus lateralis oblique. Used to, still, a master’s thesis, located at Portal Capes, plus textbooks and atlases of anatomy. Among the 27 surveyed, only two do not recognize these portions as independent structures, considering the differences in fiber orientation. Of the 18 studied anatomy books, no mention such parts. However, eight anatomy books describe differences in trajectory of fiber insertions of the vastus lateralis and vastus medialis. Before this study it was concluded that these portions have not only morphological differences but also in other respects proved through scientific studies being published in some of them considered independent muscle suggesting inclusion of muscles in Anatomical Nomina.

Effectiveness of electrical stimulation on rehabilitation after ligament and meniscal injuries: a systematic review / Efetividade da estimulação elétrica na reabilitação pós-lesões ligamentares e meniscais: uma revisão sistemática

CONTEXT AND OBJECTIVE: Electrical stimulation (ES) is widely used to strengthen muscles following ligament and meniscal injuries. The aim of this study was to evaluate the effectiveness of ES for rehabilitation after soft tissue injuries of the knee treated surgically or conservatively. DESIGN AND SETTING: Systematic review at the Brazilian Cochrane Center. METHODS: We searched the Cochrane Central Register of Controlled Trials (2010, Issue 12), Medline (Medical Analysis and Retrieval System Online) via PubMed (1966 to December 2010), Embase (Excerpta Medica database, 1980 to December 2010), Lilacs (Literatura Latino-Americana e do Caribe em Ciências da Saúde, 1982 to December 2010), and PEDro (Physiotherapy Evidence Database, 1929 to December 2010). The studies included were randomized controlled trials using ES to increase muscle strength for rehabilitation of patients with soft tissue injuries of the knee. Two authors independently evaluated studies for inclusion and performed data extraction and methodological quality assessment. RESULTS: Seventeen studies evaluating ES after anterior cruciate ligament reconstruction and two studies evaluating ES after meniscectomy were included. There was a statistically significant improvement in quadriceps strength through ES (mean difference, MD: -32.7; 95 percent confidence interval, CI: -39.92 to -25.48; n = 56) and in functional outcomes (MD -7; -12.78 to -1.22; n = 43) six to eight weeks after surgical reconstruction of the anterior cruciate ligament. CONCLUSION: There is evidence that ES coupled with conventional rehabilitation exercises may be effective in improving muscle strength and function two months after surgery.

CONTEXTO E OBJETIVO: A estimulação elétrica (ES) é amplamente utilizada para fortalecimento muscular após lesões ligamentares ou meniscais do joelho. O objetivo deste estudo foi avaliar a efetividade da ES na reabilitação de lesões de tecidos moles do joelho tratadas de forma cirúrgica ou conservadora. TIPO DE ESTUDO E LOCAL: Revisão sistemática no Centro Cochrane do Brasil. MÉTODOS: Realizamos uma busca no Cochrane Central Register of Controlled Trials (2010, Issue 12), Medline (Medical Analysis and Retrieval System Online) via PubMed (1966 até dezembro 2010), Embase (Excerpta Medica Database, de 1980 até dezembro 2010), Lilacs (Literatura Latino-Americana e do Caribe em Ciências da Saúde, de 1982 até dezembro de 2010), and PEDro (Physiotherapy Evidence Database, de 1929 até dezembro de 2010). Os estudos incluídos foram ensaios clínicos randomizados que utilizaram a ES com o objetivo de aumento de força muscular na reabilitação de pacientes com lesões de tecidos moles. Dois autores avaliaram os estudos para inclusão de forma independente e realizaram a extração de dados e avaliação da qualidade metodológica. RESULTADOS: Dezessete estudos incluídos utilizaram a ES após a reconstrução do ligamento cruzado anterior e dois estudos após meniscectomia. Houve melhora estatisticamente significante na força do quadríceps através da ES (diferença média, MD -32.7; 95 por cento intervalo de confiança, IC -39.92 to -25.48; n = 56) e nos desfechos funcionais (MD -7; -12.78 to -1.22; n = 43), seis a oito semanas após cirurgia de reconstrução do ligamento cruzado anterior. CONCLUSÃO: Há evidências de que a ES combinada a exercícios de reabilitação convencional pode ser efetiva na melhora da força muscular e função dois meses após cirurgia.

Functional and morphological changes in the quadriceps muscle induced by eccentric training after ACL reconstruction / Alterações funcionais e morfológicas do quadríceps induzidas pelo treinamento excêntrico após reconstrução do LCA

OBJECTIVES: The purpose of this study was to investigate the contributions of functional and morphological factors in the recovery of the quadriceps muscle after anterior cruciate ligament (ACL) reconstruction. METHODS: Nine subjects (31.3±5.8 years) underwent eccentric exercise sessions twice a week for 12 weeks. Quadriceps muscle function was evaluated using an isokinetic dynamometer (isometric and eccentric peak torque) and electromyography (RMS). Morphological changes were measured using magnetic resonance imaging. RESULTS: The initial evaluation showed a significant deficit in knee extensor torque in the involved limb and significant muscle atrophy along the length of the quadriceps. EMG activity was lower in all tested situations. Eccentric training significantly increased isokinetic torque (from 199±51 to 240±63, p<0.05, respectively) and quadriceps area, with the greatest hypertrophy in the proximal thigh region (from 169±27 to 189±25.8 cm², p<0.01). The EMG activity of vastus medialis increased after the first six weeks of eccentric training. The increased extensor torque was correlated with quadriceps cross-sectional area (r=0.81, p<0.01) and EMG activity (r=0.69, p<0.05). After twelve weeks of training, there was a correlation only between torque and cross-sectional area (r=0.78, p<0.01). CONCLUSIONS: 1) eccentric training proved to be a potent resource for the quadriceps recovery, both morphologically and functionally, 2) the contributions of functional and morphological factors varied according to the length of training.

OBJETIVOS: O propósito deste estudo foi avaliar as contribuições dos fatores funcionais e morfológicos na recuperação da força muscular do quadríceps femoral após reconstrução do Ligamento Cruzado Anterior (LCA). MÉTODOS: Nove indivíduos (31,3±5,8 anos) foram treinados por meio de contrações excêntricas máximas, duas vezes por semana, durante 12 semanas. A função do quadríceps foi avaliada pela dinamometria isocinética (pico de torque isométrico e excêntrico) e pela eletromiografia (EMG). As alterações morfológicas foram mensuradas por meio de ressonância magnética (RNM). Na avaliação inicial, observou-se significativo déficit no torque extensor do joelho do membro acometido, com hipotrofia muscular de todo o quadríceps e redução na atividade EMG, quando comparado ao membro não-acometido. RESULTADOS: O treinamento excêntrico produziu aumento no torque excêntrico a 30º/s (de 199±51 Nm para 240±63 Nm, p<0,05) e no volume muscular, sendo que maiores hipertrofias ocorreram na região proximal da coxa (de 169±27 para 189±25,8 cm², p<0,01). A atividade EMG do Vasto Medial (VM) aumentou nas primeiras seis semanas de treinamento. O aumento no torque extensor demonstrou correlação positiva com o aumento no volume (r=0,81, p<0,01) e na atividade eletromiográfica (EMG) (r=0,69, p<0,05) nas primeiras seis semanas. Após 12 semanas de treinamento, houve correlação apenas entre o aumento do torque e do volume (r=0,78, p<0,01). CONCLUSÕES: 1) O treinamento excêntrico mostrou-se como potente recurso tanto na recuperação dos fatores morfológicos como funcionais do músculo quadríceps; 2) A contribuição dos fatores neurais e morfológicos varia em função do período de treinamento.

Estudio piloto sobre entrenamiento físico durante hemodiálisis / A pilot study on physical training of patients in hemodialysis

Background: Exercise training during the dialytical procedure may have positive cardiovascular effects and prevent or revert muscle wasting in patients undergoing chronic hemodialysis. Aim: To evaluate the effects of an exercise training program in patients undergoing chronic hemodialysis. Material and Methods: Fifteen patients on chronic hemodialysis aged 21 to 69 years (three females) were included in the study. Nine of these were included in an exercise training program. During 16 weeks, exercise sessions were carried out during each dialytical procedure that included a warm-up period, aerobic exercises done using standing cycles, and resistance exercises, performed using Thera-Band® elastic bands and loops. Borg scale was used to control the intensity of training. At baseline and at the end of the study, a blood sample prior and after the dialytical procedure was obtained to measure C reactive protein, tumor necrosis factor α and interleukin 6. Quadriceps muscle strength, six minutes´ walk and quality of life using the SF-36 questionnaire, were also measured. Results: Four experimental subjects did not complete the study period, two that withdrew before starting, one due to problems with the venous access and one that decided to withdraw after 1 month of training. Among the five patients that finished the training period, significant improvements in the six minutes´ walk and quadriceps strength were observed in the experimental group. No significant changes were observed among controls. No changes were observed in either group in C reactive protein, tumor necrosis factor and interleukin 6 levels or quality of life. Conclusions: Among patients undergoing chronic hemodialysis exercise training improves endurance and muscle strength.

Comparison of electrical stimulation and isometric training on isokinetic strength of knee extensors: a randomized clinical trial

The purposes of this study were [1] to investigate and [2] to compare effects of isometric exercises and electrical stimulation on isokinetic strength for healthy quadriceps femoris muscle. Twenty healthy volunteers [range, 20-25; mean age, 20.9 +/- 1.1 yr] participated in the study. All participants were divided into two groups [Group I and Group II]. Each group consisted of 10 subjects. While Group I received electrical stimulation with Russian current, Group II trained with maximal volunteer isometric exercises [10s contraction and 50 s relaxing periods with 10 repetitions] for three days per week for six weeks. Before and after the training program, each subject was evaluated using the following tests; anthropometrical measurements, fixed weight repetition, step-up, decline squat, single leg hop, and isokinetic assessments [peak torque, work per repetition, initial peak torque, fatigue index, total work done,%BW]. After a 6-week training program, significant differences in terms of physical functioning and isokinetic parameters in the two groups were found [p<0.05]. Physical functioning and isokinetic strength of quadriceps femoris muscle were seen to be increased in two group after training programs [p<0.05]. There were no significant differences between the groups [p>0.05]. Quadriceps femoris hypertrophy was only found in electrical stimulation group [p<0.05]. The results obtained from this study show that the two strengthening techniques just used in the study can be used to improve muscle strength, performance and isokinetic parameters in healthy quadriceps femoris muscle [p<0.05]. But, there is no superiority on each other. In conclusion, these results indicate that electrical stimulation and maximal volunteer isometric exercises can be used to increase isokinetic strength as an alternative for isokinetic dynamometer in clinical setting

Relação entre o ângulo quadriciptal (ÂQ) e a distribuição da pressão plantar em jogadores de futebol / Relationship between quadriceps angle (Q) and plantar pressure distribution in football players

OBJETIVOS: Verificar possível associação entre ângulo quadriciptal (ÂQ) e distribuição de pressão plantar em jogadores de futebol, comparando-os com indivíduos não praticantes da modalidade. MÉTODOS: Cento e vinte e um participantes do sexo masculino foram selecionados: 50 jogadores de futebol (JF) e 71 sujeitos para o grupo controle (GC). Avaliaram-se concomitantemente o ÂQ, por meio do Software para Avaliação Postural (SAPO), e a pressão plantar, pela plataforma F-Scan/F-Mat System. Para verificar correlação entre o ÂQ e os valores de picos de pressão em quatro segmentos do pé (antepé medial e lateral, médio-pé e retropé), utilizou-se o Coeficiente de Pearson (r) para análises paramétricas. O teste t independente foi empregado para comparar isoladamente essas mesmas variáveis entre os grupos. A normalidade dos dados foi verificada pelos valores de skewness, adotando nível de significância de 5 por cento. RESULTADOS: Encontrou-se correlação negativa e fraca (r=-0,32) somente entre ÂQ e médio-pé direito. Os grupos diferiram quanto ao ÂQ bilateralmente, sendo que o grupo JF teve média de 11,36º, e GC, de 13,80º à direita e de 11,03º contra 13,96º à esquerda, respectivamente. Em relação à pressão plantar, o JF teve maior média de força nas faces laterais do antepé direito (0,77 contra 0,63 kg/cm²) e esquerdo (0,65 e 0,54 kg/cm²), enquanto o GC apresentou maior pico de pressão no médio-pé esquerdo (JF: 0,37 e GC: 0,46 kg/cm²). CONCLUSÕES: Não houve relação entre os valores de ÂQ na distribuição da pressão plantar nos jogadores de futebol. Os atletas apresentaram, porém, ÂQ diminuído e maiores picos de pressão nas faces laterais de ambos os pés, o que sugere alinhamento em varo dos joelhos e distribuição supinada das bases plantares.

OBJECTIVES: To determine whether there is an association between the Q-angle (Q) and the distribution of plantar pressure in football players, and to compare the characteristics of these athletes with non-practitioners of this sport. METHODS: 121 male participants were selected: 50 football practitioners (FP) and 71 non-practitioners (NP). We concurrently evaluated the Q-angle and the plantar pressure through the software of postural assessment (SPA) and the F-Mat System, respectively. To verify the correlation between the Q-angle and peak pressure values in four segments of the foot (medial and lateral forefoot, medium-foot and hind-foot), the Pearson coefficient (r) for parametric analysis was used. The independent t-test was used to compare these variables between the groups. Data normality was verified by the skewness values, adopting a significance level of 5 percent. RESULTS: A negative and weak correlation was found (r=-0.32) between the Q-angle and the plantar pressure in the right medium-foot. The groups differed with regards to the right Q-angle (11.36º in FP versus 13.80º in NP) and the left Q-angle (11.03º in FP versus 13.96º in NP). Plantar pressure was also different between the groups, with FP showing higher mean values for the right side and for the left side of the forefoot (0.77 kg/cm² in FP versus 0.63 kg/cm² in NP, and 0.65 kg/cm² in FP versus 0.54 kg/cm² in NP, respectively). However, mean peak pressure values for the left medium-foot were higher among NP (0.37 kg/cm² in FP versus 0.46 kg/cm² in NP). CONCLUSIONS: There was no evidence of an association between the Q-angle and the distribution of plantar pressure in FP. The athletes showed reduced Q-angle values and higher mean peak pressure values for the right and left aspects of the forefoot, suggesting a varus malalignment and a supine distribution of plantar bases.

Comparative study between 2 cm limited quadriceps exposure minimal invasive surgery and conventional total knee arthroplasty in quadriceps function: prospective randomized controlled trial.

OBJECTIVE: To compare the recovery time and straight leg raising test after total knee replacement between 2 cm limited quadriceps exposure minimally invasive surgery total knee replacement (2cm Quad MIS TKR) and conventional total knee replacement. MATERIAL AND METHOD: The authors conducted a randomized controlled trial in 40 osteoarthritis knee patients in two groups. Total replacement was performed by the same surgeon and the same prosthesis was used in each group. The function of Quadriceps muscle (straight leg raising test) range of motion was evaluated postoperatively. RESULTS: The 40 patients enrolled in the present study followed the complete study. After surgery with 2 cm Quad MIS TKA, quadriceps function recovery time was faster than with conventional total knee replacement. The quadriceps function was evaluated by the straight leg raising test (SLRT) in sitting and lay down position and the time of ambulation. CONCLUSION: Operative treatment with 2 cm Quad MIS TKA improved recovery time in quadriceps function when compared with conventional total knee replacement.

Correlation between serum vitamin D (25(OH)D) concentration and quadriceps femoris muscle strength in Indonesian elderly women living in three nursing homes.

AIM: to investigate the correlation between serum vitamin D (25(OH)D) concentration and quadriceps femoris muscle strength. METHODS: this was a cross-sectional correlative study, conducted at three nursing homes in Jakarta and one nursing home in Bekasi in January 2005. The subjects were women aged 60 years or above. Those selected study subjects underwent quadriceps femoris muscle strength examination with Cybex dynamometer with 150 degrees/second speed, twice (three repetitions with 30 second rest time). The 25 (OH)D concentration was measured by ELISA. RESULTS: out of 67 subjects who met the required criteria for this study, five subjects withdrew from the study during muscle strength examination. The mean age was 71.1 (SD 7.2) years old while the mean serum vitamin D concentration was 68.2 (SD 21.6) nmol/l. Vitamin D deficiency (<or= 50 nmol/l) was found in 22.6% of subjects. It was also found that the median (minimum-maximum) quadriceps femoris muscle strength was 40.00 (11-116) N.m. Approximately 82.3% of the subjects were of generalized muscle weakness. Correlation was found between serum 25 (OH)D concentration and quadriceps femoris muscle strength (r = 0.327; P = 0.009). CONCLUSION: this study reveals that serum 25 (OH) D concentrations in Indonesian elderly women is correlated with quadriceps femoris muscle strength. The proportion of elderly women with muscle weakness is higher than the normal ones. The group with older age shows higher proportion of muscle weakness. Most subjects have normal serum vitamin D concentration.

Estudo eletromiográfico dos músculos motores primários da articulação do joelho na mesa romana: estudo de caso / Eletromyography study of the primary motors muscles of the knee articulation executed in roman table: study of case

Através dos estudos eletromiográficos é que se tem conhecido a efetiva participação dos músculos esqueléticos. Participaram do estudo 05 sujeitos do sexo masculino, na faixa etária entre 17 e 22 anos, praticantes de musculação. Foram utilizados eletrodos de superfície. Os músculos reto femoral, vasto lateral e vasto medial foram analisados no movimento de extensão do joelho realizado sentado na mesa romana; os músculos bíceps femoral, semimembranoso e semitendinoso foram analisados no movimento de flexão do joelho em decúbito ventral na mesa romana. Os resultados expressos em RMS foram: 543,86 (±127,39) para o músculo semimembranoso, 400,08 (±124,10) para o semitendinoso, 222,92 (±69,28) o valor do bíceps femoral, 288,12 (±152,4) para o músculo reto femoral, 215,63 (±117,30) para o músculo vasto lateral e 190,58 (±75,01) o valor do vasto medial. As cargas máximas utilizadas foram maiores no movimento de extensão do joelho. Os resultados demonstraram maior participação dos músculos flexores do joelho quando coparado com os extensores.

Through the electromyography studies it is that is had known the effective participation of the skeletal muscle. They participated in the study five subject of the masculine sex, in the age group among 17 and 22 years. Surface electrodes were used. The vastus lateralis, vastus medialis, rectus femoris muscles was analyzed in the extension movement of the knee, sat down in the roman table; the biceps femoris, semimembranosus and semitendinosus muscles was analyzed in the flexion movement of the knee, in decubitus ventralis, in the roman table. The results, expressed in RMS, were: 543,86 (±127,39) for the semimembranosus muscle, 400,08 (±124,10) for semitendinosus, 222,92 (±69,28) the value of the biceps femoris muscles, 288,12 (±152,4) for the rectus femoris, 215,63 (±117,30) for the vastus lateralis muscle and 190,58 (±75,01) the value of vastus medialis. The used maximum loads were larger in the extension movement of the knee. The results demonstrated larger participation of the flexors muscles of he knee when compared with the extensors muscles.