Delayed onset muscle soreness intensity affects muscular performance / El Dolor muscular de aparición tardía afecta el desempeño muscular

Abstract Background: The study of functional impact of delayed onset muscle soreness has been limited to describe the decline on maximal isometric contraction, but muscular work and time to peak torque has not been examined yet. Purpose: To describe the changes induced by a session of lengthening contractions on muscle performance and delayed onset muscle soreness (DOMS). Methods: A quasi-experimental study was conducted in the Institutional laboratory; Twenty healthy men; mean age 21 SD 0.34 were recruited, all subjects performed 200 lengthening contractions of the quadriceps at 120°/s. Isometric and isokinetic peak torque, muscular work, time to peak torque, DOMS and creatine kinase activity were assessed at baseline, 48 h and 96 h post-exercise. The muscle performance was assessed with an isokinetic dynamometer and DOMS with a visual analog scale (VAS). Results: Relative to baseline, isometric and isokinetic peak torque and muscular work decreased in ~30% at 48 h post-exercise; delayed onset muscle soreness increased ~300%, which remained at 96 h post-exercise. Conclusions: These reflect that the decline in muscular performance is due to the changes in peak torque and muscular work, which has greater implications on muscle function. No changes were detected in time to peak torque. The alterations in muscular performance variables are accompanied by delayed onset muscle soreness which has also a negative impact on force production (29% of the drop on peak torque is explain by soreness intensity).

Resumen Introducción: Los estudios de impacto funcional del dolor muscular de aparición tardía (DMAT) se han limitado a describir la disminución de la contracción isométrica máxima, pero aún no se ha examinado el trabajo muscular y el tiempo del torque máximo. Objetivo: Describir los cambios inducidos por una sesión de ejercicio excéntrico sobre el rendimiento muscular y DMAT. Método: se realizó un estudio cuasi-experimental, los participantes fueron veinte hombres sanos; edad media 21 DE 0,34, todos los sujetos realizaron 200 contracciones excéntricas del cuádriceps a 120°/s. Se evaluó el torque pico isométrico e isocinético, el trabajo muscular, el tiempo hasta el torque máximo, DMAT y la actividad de la creatina quinasa al inicio, 48 h y 96 h después del ejercicio, el rendimiento muscular se evaluó con un dinamómetro isocinético y DOMS con una escala análoga visual (EAV). Resultados: en relación con la línea de base, el torque pico isométrico e isocinético y el trabajo muscular disminuyeron en ~ 30 % a las 48 h post-ejercicio; El dolor muscular de aparición tardía aumentó ~300 %, que permaneció 96 h después del ejercicio. Conclusiones: los resultados reflejan que la disminución del rendimiento muscular se debe a los cambios en el torque pico y trabajo muscular, lo que tiene mayores implicaciones en la función muscular. No se detectaron cambios en el tiempo hasta el torque máximo. Las alteraciones en las variables de rendimiento muscular se acompañan de DMAT que también tiene un impacto negativo en la producción de fuerza (el 29 % de la caída en el torque máximo se explica por la intensidad del dolor).

Isometric exercises have high responsiveness to lower limbs / Exercícios isométricos possuem alta responsividade para membros inferiores

INTRODUCTION: For post-surgical rehabilitation of the anterior cruciate ligament, the medialis and the lateralis vastus need to be worked on for good recovery. There is the discussion about the isometric and isotonic exercises to be used in the rehabilitation phase, and their results diverge in the literature. OBJECTIVE: This study aims to compare the activation of the medialis and the lateralis vastus in isometric and isotonic exercises. METHODS: Eleven subjects (seven men and four women) physically active and experienced in resistance training participated in the study. Anamnesis, anthropometric assessment, 10 Repetition maximum (RM) load test, maximum voluntary isometric contraction test and squat test were performed. RESULTS: For the vastus lateralis of the right leg, the electromyographic activity was significantly higher in the maximal isometric voluntary contraction compared to the dynamic squatting (p<0.05). The same was observed for the left leg (p<0.05). CONCLUSION: Recruitment of the medial and the lateral vastus in isometric exercises is higher in relation to isotonic exercises.

INTRODUÇÃO: Para a reabilitação pós-cirúrgica do ligamento cruzado anterior, os vastos medial e lateral precisam ser trabalhados visando uma boa recuperação. Discute-se a respeito dos exercícios isométricos e isotônicos a serem utilizados na fase de reabilitação, tendo seus resultados divergentes na literatura. OBJETIVO: Assim, o objetivo do presente estudo é comparar a ativação dos vastos medial e lateral em exercícios isométricos e isotônicos. MÉTODOS: Participaram deste estudo 11 sujeitos (sete homens e quatro mulheres), fisicamente ativos e com experiência em musculação. Foi realizada a anamnese, a avaliação antropométrica, o teste de carga de 10 repetições máximas (RM), o teste de contração voluntária isométrica máxima e o teste de agachamento. RESULTADOS: No vasto lateral da coxa direita, a atividade eletromiográfica foi significativamente maior na contração voluntária isométrica máxima em relação ao agachamento dinâmico (p<0,05). O mesmo foi observado na coxa esquerda (p<0,05). CONCLUSÃO: O recrutamento dos vastos medial e lateral em exercícios isométricos é maior em relação a exercícios isotônicos.

Beta-alanine supplementation improves isometric, but not isotonic or isokinetic strength endurance in recreationally strength-trained young men.

ß-Alanine (BA) supplementation may be ergogenic during high-intensity exercise, primarily due to the buffering of hydrogen cations, although the effects of beta-alanine supplementation on strength endurance are equivocal. The aim of the study was to determine the effects of 4 weeks of beta-alanine supplementation on skeletal muscle endurance using a battery of performance tests. This study employed a parallel group, repeated measures, randomised, double-blinded and placebo-controlled design. Twenty recreationally strength-trained healthy males completed tests of isotonic strength endurance (repeated bench and leg press), along with tests of isometric and isokinetic endurance conducted using an isokinetic dynamometer. Tests were performed before and after a 4 week intervention, comprising an intake of 6.4 g day-1 of BA (n = 9) or placebo (maltodextrin, n = 11). Time-to-exhaustion during the isometric endurance test improved by ~ 17% in the BA group (p < 0.01), while PL remained unchanged. No significant within-group differences (p > 0.1) were shown for any of the performance variables in the isokinetic test (peak torque, fatigue index, total work) nor for the total number of repetitions performed in the isotonic endurance tests (leg or bench press). Four weeks of BA supplementation (6.4 g day-1) improved isometric, but not isokinetic or isotonic endurance performance.

Do isometric, isotonic and/or isokinetic strength trainings produce different strength outcomes?

INTRODUCTION: Several studies have been developed to determine which type of muscular action (isometric, isotonic and isokinetic) elicits more gains in functional strength and muscle mass. The comparisons between training outcomes are inconclusive due to lack of exercise standardization. OBJECTIVE: To compare muscle strength, mass, and functional performance in response to isometric, isotonic, and isokinetic contractions, when training loads (volume and intensity) are equated. METHOD: Data were derived from a university community-recruited sample (n = 31 men). INTERVENTIONS: Untrained men were assigned to isotonic (IT), isometric (IM), or isokinetic (IK) group, and trained their dominant quadriceps muscle 3 sessions/week for 8 weeks with a dynamometer. Muscle strength was assessed using Cybex 6000 dynamometer; the triple-hop-distance test was used to assess functional performance, and dual energy x-ray absorptiometry to assess lean muscle mass. RESULTS: After training, muscle lean muscle mass increased in isometric (+3.1%, p < 0.01) and isotonic groups (+3.9%, p < 0.01); only the isokinetic group showed a significant improvement in the triple-hop-distance test (4.84%, p < 0.01). CONCLUSION: Clinicians should consider isometric training as an alternative for isotonic training to gain muscle mass, and isokinetic training to improve functional performance of daily activities and/or sports.

Muscle function deterioration in patients with haemophilia: Prospective experience from Costa Rica.

INTRODUCTION: In haemophilia, recurrent joint bleeds are responsible for the development of chronic joint damage, because blood induces biochemical changes in joint structures. Joint degeneration is a long process, and structural damage is often preceded by joint dysfunction, which is represented by quantitative and qualitative changes in the contraction pattern of muscles around the joints. Muscle function in patients with haemophilia is still poorly investigated. AIM: The aim of this 2-year prospective study was to assess the changes in muscle function of lower limbs in a group of patients affected with haemophilia in San José, Costa Rica. METHODS: Muscle function of lower limbs was assessed by means of surface electromyography (sEMG) accomplished at study enrolment and after 2 years of follow-up. Gluteus medius, vastus medialis, biceps femoris, gastrocnemius and tibialis anterior were examined. All patients underwent concurrent clinical examination using Haemophilia Joint Health Score (HJHS). RESULTS: Sixty patients aged 2-43 years with severe haemophilia underwent clinical and sEMG evaluation. Thirty-two patients (53%) had target joints. sEMG parameters were altered in all patients and were not correlated to the presence of target joints and/or an abnormal HJHS. Muscle function deterioration was observed after 2 years of follow-up despite an unmodified HJHS. CONCLUSIONS: Muscle function of lower limbs as detected by means of sEMG was impaired in patients with haemophilia irrespective of the presence of overt joint damage. sEMG is a simple and sensitive assessment tool able to detect muscle dysfunction and so favouring the implementation of early rehabilitation therapy.

Photobiomodulation improves motor response in patients with spinal cord injury submitted to electromyographic evaluation: randomized clinical trial.

Photobiomodulation is a treatment that has been widely used in neurotrauma and neurodegenerative diseases. In the present study, low-level laser therapy was administered to patients with spinal cord injury. Twenty-five individuals were divided into two groups: placebo photobiomodulation plus physiotherapy and active photobiomodulation plus physiotherapy. Electromyographic evaluations were performed before and after 12 sessions of phototherapy as well as 30 days after the end of treatment. In the active phototherapy group, median frequency values of the brachial biceps and femoral quadriceps muscles were higher at rest and during isotonic contraction 30 days after photobiomodulation (p = 0.0258). No significant results were found regarding the rest and isotonic conditions in the pre-photobiomodulation period (p = 0.950) or immediately following photobiomodulation (p = 0.262). The data provide evidence that phototherapy improves motor responses in individuals with spinal cord injury, as demonstrated by differences in the EMG signal before and after treatment. TRIAL REGISTRATION: NCT 03031223.

Balanced Diet-Fed Fat-1 Transgenic Mice Exhibit Lower Hindlimb Suspension-Induced Soleus Muscle Atrophy.

The consequences of two-week hindlimb suspension (HS) on skeletal muscle atrophy were investigated in balanced diet-fed Fat-1 transgenic and C57BL/6 wild-type mice. Body composition and gastrocnemius fatty acid composition were measured. Skeletal muscle force, cross-sectional area (CSA), and signaling pathways associated with protein synthesis (protein kinase B, Akt; ribosomal protein S6, S6, eukaryotic translation initiation factor 4E-binding protein 1, 4EBP1; glycogen synthase kinase3-beta, GSK3-beta; and extracellular-signal-regulated kinases 1/2, ERK 1/2) and protein degradation (atrophy gene-1/muscle atrophy F-box, atrogin-1/MAFbx and muscle RING finger 1, MuRF1) were evaluated in the soleus muscle. HS decreased soleus muscle wet and dry weights (by 43% and 26%, respectively), muscle isotonic and tetanic force (by 29% and 18%, respectively), CSA of the soleus muscle (by 36%), and soleus muscle fibers (by 45%). Fat-1 transgenic mice had a decrease in the ω-6/ω-3 polyunsaturated fatty acids (PUFAs) ratio as compared with C57BL/6 wild-type mice (56%, p < 0.001). Fat-1 mice had lower soleus muscle dry mass loss (by 10%) and preserved absolute isotonic force (by 17%) and CSA of the soleus muscle (by 28%) after HS as compared with C57BL/6 wild-type mice. p-GSK3B/GSK3B ratio was increased (by 70%) and MuRF-1 content decreased (by 50%) in the soleus muscle of Fat-1 mice after HS. Balanced diet-fed Fat-1 mice are able to preserve in part the soleus muscle mass, absolute isotonic force and CSA of the soleus muscle in a disuse condition.

Acute effect of different stretching methods on the strength performance in successive series / Efeito agudo de diferentes métodos de alongamento sobre o desempenho da força em séries sucessivas

ABSTRACT There is still no consensus about the use of stretching before strength exercises in successive series. Thus, the aim was to verify the acute effect of two stretching methods on the strength performance in the bench press exercise. Trained subjects performed 3 sets of 8 to10-RM in the bench press immediately after the static stretching (SS), Proprioceptive Neuromuscular Facilitation (PNF) or control condition. There was a significant decrease in repetitions in the second and third series compared to the first for all conditions. There was no significant difference in the number of repetitions or total volume between the conditions with and without stretching. The SS and PNF induced no negative effect on strength performance and can be used prior to this exercise

RESUMO Ainda não há consenso sobre a utilização de alongamentos antes de exercícios de força em séries sucessivas. Sendo assim, o objetivo foi verificar o efeito agudo de dois métodos de alongamento sobre o desempenho da força no exercício supino reto. Indivíduos treinados realizaram 3 séries de 8 a 10-RM no supino reto imediatamente após o alongamento estático (AE), Facilitação Neuromuscular Proprioceptiva (FNP) ou condição controle. Foi encontrada queda significativa das repetições na segunda e terceira séries em comparação à primeira em todas as condições. Não houve diferença significativa no número de repetições ou no volume total entre as condições com e sem alongamento. O AE e a FNP não causaram impacto negativo no desempenho da força, podendo, assim, serem utilizados previamente a esse exercício.

Reduction of contractility and reactivity in isolated lymphatics from hemorrhagic shock rats with resuscitation

PURPOSE: To evaluate the changes of contractility and reactivity in isolated lymphatics from hemorrhagic shock rats with resuscitation. METHODS: Six rats in the shock group suffered hypotension for 90 min by hemorrhage, and resuscitation with shed blood and equal ringers solution. Then, the contractility of lymphatics, obtained from thoracic ducts in rats of the shock and sham groups, were evaluated with an isolated lymphatic perfusion system using the indices of contractile frequency (CF), tonic index (TI), contractile amplitude (CA) and fractional pump flow (FPF). The lymphatic reactivity to substance P (SP) was evaluated with the different volume of CF, CA, TI and FPF between pre- and post-treatment of SP at different concentrations. RESULTS: The CF, FPF, and TI of lymphatics obtained from the shocked rats were significantly decreased than that of the sham group. After SP stimulation, the ∆CF (1×10-8, 3×10-8, 1×10-7, 3×10-7 mol/L), ∆FPF (1×10-8, 3×10-8, 1×10-7 mol/L), and ∆TI (1×10-8 mol/L) of lymphatics in the shock group were also obviously lower compared with the sham group. In addition, there were no statistical differences in CA and ∆CA between two groups. CONCLUSION: Lymphatic contractility and reactivity to substance P appears reduction following hemorrhagic shock with resuscitation.(AU)

Efeito da estimulação abdominal sobre o contato plantar na lesão encefálica adquirida / Effects of abdominal stimulation on plantar contact in case of the acquired brain injury

Objetivo: Verificar a influência da estimulação dos músculos abdominais em pacientes com LEA sobre o contato plantar. Método: Participaram oito indivíduos com idade média de 46±15,9 anos. Para avaliação de pressão plantar, utilizou-se um baropodômetro, com coleta antes e após a estimulação abdominal, a qual foi realizada com os pacientes posicionados no divã com apoio na região sacral/quadril e joelhos flexionados em 90°, e pés, mãos e tronco superior sem apoio. Estes músculos foram estimulados a realizar contração por desequilíbrio provocado pela diminuição na base de suporte (apoiados somente em sacro). Assim, realizou-se contração isométrica para o posicionamento, intercalada por contrações isotônicas de curta amplitude, para recuperação do equilíbrio. Resultados: Na distribuição de pressão plantar, observou-se que o retropé e mediopé apresentam maior e menor pico de pressão, respectivamente (p<0,05). Houve diminuição do pico de pressão bilateral, especialmente no pé direito (p=0,05), e aumento da área de contato plantar dos pacientes, principalmente no pé esquerdo (p=0,03). Conclusão: A estimulação aguda da musculatura abdominal influenciou na área de contato e nos valores de pico de pressão plantar, mesmo com a amostra heterogênea estudada.

Objective: To evaluated the influence of abdominal stimulation in patients with acquired brain injury on plantar pressure distribution. Method: Eight individuals aged 46±15.9 years were evaluated. Analysis of plantar pressure distribution was performed through a baropodometer. The collection was performed before and after abdominal stimulation. The abdominal stimulation was performed with the patient positioned on the divan with support in the region sacral / hip and knees flexed at approximately 90º, and feet, hands and upper trunk without support. The contraction of these muscles was obtained through the loss of balance caused by the decrease of the support base (patients supported only by the sacrum. Thus, isometric contraction was performed for positioning, alternating with isotonic contractions of short duration to recover balance. Results: In plantar pressure distribution, the hindfoot and midfoot regions showed, respectively, higher and lower peak pressures (p<0.05). Also, there was less pressure peak bilaterally, especially in the right foot (p=0.05), and an increase in plantar contact surface in the patients, mainly in the left foot (p=0.03). Conclusion: We conclude that acute stimulation of the abdominal muscles influences the contact surface and the values of peak plantar pressure, even with a heterogeneous sample studied.

Efeitos de contraceptivo hormonal oral sobre o grau de força e composição corporal de jogadoras de vôlei: um estudo piloto / Effects of oral hormonal contraceptive on the strength level and body composition of volleyball female players: a pilot study

Verificar os efeitos dos contraceptivos hormonais orais (CO) sobre o grau de força muscular e na composição corporal de mulheres jovens atletas. Participaram desse estudo 12 mulheres jovens adultas com idade superior a 18 anos, atletas amadoras de voleibol, que participavam ativamente de treinos e competições. A amostra foi divida em Grupo Contraceptivo (GCO, n=7) e Grupo Não Contraceptivo (GNCO, n=5). Foi aplicado um questionário sobre características sociodemográficas, comportamentais, de saúde e relacionadas ao treinamento. Realizaram-se medidas antropométricas, testes de força por dinamometria e de carga de uma repetição máxima. A análise dos dados foi realizada através da análise descritiva (média ± desvio padrão) e inferencial (teste t de Student não pareado ou teste de Wilcoxon não pareado) e o nível de significância aceito foi de p<0,05. Na escolha do CO como método contraceptivo, a maioria das atletas do grupo que GCO fazem uso de contraceptivos orais de terceira geração, fazem uso dos mesmo há pelo menos 5 anos e motivaram-se a usar o medicamento por sua eficiência e eficácia no controle de natalidade. As atletas do grupo GNCO utilizavam a camisinha como método contraceptivo. Em relação a composição corporal, as atletas do grupo GCO apresentaram medidas de dobras cutâneas, circunferência corporal, percentual de gordura e peso mais elevados do que as atletas do grupo GNCO, porém em nenhum dos grupos foi observado um percentual de gordura equivalente ou superior a 25%, valor considerado como na média para mulheres com idade entre 25 e 35 anos. Nenhuma das variáveis analisadas apresentou associação estatisticamente significativa com a ingestão de CO e alterações de força e performance atlética; apenas no valor da circunferência da coxa medial encontrou-se significativa limítrofe (p=0,05). No presente estudo, os COs não exerceram efeitos significantes sobre a força muscular e composição corporal de jovens atletas amadoras de voleibol.

The study aimed to evaluate potential effects of hormonal contraceptives (OC) on muscle strength and body composition in young female amateur volleyball players. Twelve women (18 or older) participated in the study, all of them were volleyball players, who were training and competing. The sample was divided into Contraceptive Group (OCG, n = 7) and Non Contraceptive Group (NOCG, n = 5). We administered a questionnaire on socio-demographic, behavioral, health-related information and training aspects. Anthropometric measurements, grip strength and maximum repetition tests were taken. Data analysis was performed with descriptive analysis (means ± standard deviations) and inferential statistics (Student's unpaired t test or Wilcoxon unpaired test) and the level of significance was set to 0.05. Among OC users, most athletes use third-generation oral contraceptives, for at least 5 years and were motivated to use the drug for their efficiency and effectiveness as a birth control method. The athletes from NOCG group used condoms as a contraceptive method. Regarding body composition, athletes from OCG group presented higher skinfolds, body circumference, body fat percentage and weight compared to athletes from NOCG group, but in none of the groups body fat was equal to or exceeded 25%, which is considered a value in average for women between the ages of 25 and 35. None of the analyzed variables showed any statistically significant association with oral contraceptives; only thigh’s circumference presented borderline significance (p=0.05). In this study, hormonal contraceptives did not exert significant effects on muscle strength and body composition of young amateur volleyball players.

The remodeling of collagen fibers in rats ankles submitted to immobilization and muscle stretch protocol.

To evaluate the remodeling of collagen fibers in the articular cartilage of rat ankles, with and without immobilization, after application of muscle stretching protocol. Twenty three Wistar rats were divided into four groups: immobilized (I), n=6; immobilized and stretched (IS), n=6; stretched (S), n=6 and control (C), n=5. The animals in groups I and IS were submitted to immobilization. After the period of immobilization, the animals in groups IS and S were submitted to a muscle stretching protocol. At the end of the experiment, the animals were euthanized and the joints removed, processed and stained with Picrosirius red. The analysis was carried out using a polarized light microscope. The density of collagen fibers were quantified according to the intensity of birefringence displayed. By way of statistical analyses, the right and left hind limbs of the different groups were compared based on the total density of collagen fibers, the density of thick collagen fibers and the density of thin collagen fibers. Immobilization promoted a reduction in density of the thin fibers and of total collagen. The muscle stretching protocol after immobilization promoted a reduction in density of the total collagen and of the thick fibers, but the density of the thin fibers showed the same values as control. The collagen fibers were remodeled by the different stimuli. Immobilization was harmful to the collagen fibers and the muscle stretching protocol only recovered the thin collagen fibers.

Comparative muscle study fatigue with sEMG signals during the isotonic and isometric tasks for diagnostics purposes.

The study of fatigue is an important tool for diagnostics of disease, sports, ergonomics and robotics areas. This work deals with the analysis of sEMG most important fatigue muscle indicators with use of signal processing in isometric and isotonic tasks with the propose of standardizing fatigue protocol to select the data acquisition and processing with diagnostic proposes. As a result, the slope of the RMS, ARV and MNF indicators were successful to describe the fatigue behavior expected. Whereas that, MDF and AIF indicators failed in the description of fatigue. Similarly, the use of a constant load for sEMG data acquisition was the best strategy in both tasks.

Cardiovascular effects induced by Cymbopogon winterianus essential oil in rats: involvement of calcium channels and vagal pathway.

OBJECTIVES: This study has investigated the cardiovascular effects of the Cymbopogon winterianus essential oil (EOCW) in rats. C. winterianus is a plant used in folk medicine for the treatment of hypertension. METHODS: For the measurement of haemodynamic and ECG parameters, male Wistar rats under anaesthesia were cannulated in the abdominal aorta and lower vena cava and electrodes were subcutaneously implanted in their paws. For an in-vitro approach, the rats were killed and the superior mesenteric artery was removed and cut into rings (1-2 mm). These rings were then mounted in organ baths containing Tyrode's solution at 37 degrees C and gassed with carbogen. KEY FINDINGS: In rats, EOCW (1-20 mg/kg, i.v.) induced dose-dependent hypotension and tachycardia. These effects were not affected by L-NAME or indometacin, but were partially reduced after atropine administration. EOCW (20 mg/kg only) also induced bradycardia-associated sinoatrial blockade, junctional rhythm, and first-degree atrioventricular block, which was abolished after atropine administration or vagotomy. In arterial rings, EOCW (0.1-3000 microg/ml) induced relaxation of phenylephrine tonus that was not affected by removal of the endothelium. These relaxations were similar to those observed in rings without endothelium precontracted with KCl 80 mm. EOCW was able to antagonize the CaCl(2) (30-300 mum) induced contractions in depolarizing solution (KCl 60 mm). CONCLUSIONS: These results demonstrated that EOCW induced hypotension and vasorelaxation. These effects appeared to be mainly mediated by Ca(+2)-channel blocking. Furthermore, the higher dose of EOCW induced transient bradycardia and arrhythmias due to a cardiac muscarinic activation secondary to a vagal discharge.

Influência da distância intereletrodos e da cadência de movimento no domínio da frequência do sinal de EMG de superfície / Influence of the inter-electrodes distance and cadence of movement in the surface EMG signal frequency domain

A eletromiografia de superfície (sEMG), apesar de amplamente utilizada em investigações biomecânicas, ainda apresenta inúmeros questionamentos sobre a influência das distâncias intereletrodos (DIE) na morfologia do sinal, principalmente em contrações isotônicas. Logo, muitos dos trabalhos desenvolvidos ainda se limitam ao âmbito do laboratório de pesquisa, onde é possível estabelecer maior controle nos protocolos de registro e análise, o que não é comumente observado na prática clínico-desportiva. Dessa forma, o objetivo do estudo foi examinar os efeitos de dois protocolos de colocação de eletrodos e a realização de contrações isotônicas no domínio da frequência do sinal de sEMG. Quinze sujeitos do sexo masculino (idade: 22,8 ± 3,5 anos), todos destros, realizaram contrações dinâmicas do bíceps braquial direito com carga estimada em 20 por cento da contração voluntária máxima em três diferentes cadências (30, 45, 60bpm). Os sinais de sEMG foram registrados por meio de dois canais, cujas DIEs foram de 4,2 e 13cm, respectivamente. A avaliação dos sinais de sEMG foi baseada na frequência mediana do espectro de potencial do sinal, calculado via transformada rápida de Fourier. A DIE e a cadência foram definidas como fatores (ANOVA two-way; α = 0,05). Não foram observadas diferenças estatísticas e qualquer interação entre ambos os fatores nas três cadências (P > 0,05). Sugere-se que, independentemente da distância utilizada entre os eletrodos, uma investigação no domínio da frequência do sinal de sEMG em tarefas dinâmicas seja evitada, mesmo a partir de DIEs reduzidas, como é sugerido pela literatura, dado que variações no torque e no comprimento muscular podem corromper o sinal e, portanto, sua interpretação.

Surface electromyography (SEMG), despite being widely used in biomechanical investigations, still presents massive questioning about the influence of the distance of the inter-electrodes (DIE) in the signal morphology, especially in isotonic contractions. Thus, much of the research developed is still limited to the laboratory, where it is possible to establish better control over the recording and analysis protocols, which is not commonly observed in the clinical-sportive practice. Therefore, the aim of this study was to examine the effects of two electrodes placement protocols and the performance of isotonic contractions in the SEMG sign frequency domain. Fifteen right-handed male subjects (aged 22.8 ± 3.5 years) performed dynamic contractions of the right brachial biceps with load estimated in 20 percent of the maximum voluntary contraction in three different cadences (30, 45 and 60 bpm). The SEMG signals were registered by two channels with DIEs of 4.2 and 13 cm, respectively. The SEMG signals assessment was based on the median frequency of the potential spectrum of the signal, calculated via fast Fourier transform. DIE and cadence were defined as factors (two-way ANOVA; α = 0.05). No statistical differences or any interaction between both factors were observed in the three cadences (P> 0.05). Regardless of the distance used between electrodes, an investigation in the SEMG signal frequency domain in dynamic tasks should be avoided, even from reduced DIEs, as suggested in the literature, since variations in the torque and muscular length may disrupt the signal and hence its interpretation.

Electromyographic activity of masseter and temporal muscles with different facial types.

OBJECTIVES: To compare the electromyographic (EMG) activity of the masseter and anterior portion of temporal muscles in different vertical facial types. MATERIALS AND METHODS: Clinical examination, cephalometric analysis, and electromyographic examination were performed in 44 volunteers ranging from 18 to 35 years old. The volunteers were classified on the basis of their vertical facial characteristics into three groups-brachyfacial, mesofacial, and dolicofacial-by the grouping analysis. The EMG records were obtained with three repetitions during mandibular rest, maximum voluntary contraction in intercuspidation, and simultaneous bilateral isotonic contraction. The Kolmogorov-Smirnov and Levene tests were applied to verify the normality and homogeneity of variance. Analysis of variance and the Kruskal-Wallis test identified statistical differences among groups that did not present normality and homogeneity of distribution, respectively. Significance for all statistical tests was set at P < .05. RESULTS: At rest, only the right temporal and masseter muscles presented statistically significant differences among the groups. The differences were observed between groups 1 and 2 (P = .02) and 1 and 3 (P = .038) for the right temporal muscle, and between groups 1 and 2 (P = .029) for the right masseter muscle. Generally, group 1 presented the lowest EMG values for the four muscles evaluated during rest. For isotonic evaluation, none of the groups of muscles presented statistically significant differences. CONCLUSION: Different vertical facial types do not determine distinct patterns of EMG activity for the masseter and anterior portion of temporal muscles during rest and bilateral mastication.

Ativação seletiva do vasto medial por meio da cinesioterapia ativa / Selective ativation of vastus medialis in active kinesiotherapy

A proposta deste estudo foi realizar uma revisão bibliográfica do músculo vasto medial _VM- com o objetivo de verificar se existe evidência científica da ativação seletiva do VM utilizando-se o movimento ativo. Foi feito um estudo de revisão da hipótese de o VM ser responsável pela extensão terminal do joelho para depois ser concluído que a real função do VM é a medialização da patela. A maioria dos trabalhos revisados tentou validar, por meio de estudos eletromiográficos - EMG - a idéia corrente do recrutamento seletivo do VM em diferentes situações, variando: o tipo de contração - isométrica, isotônica concêntrica e excêntrica e isocinética; o uso do Biofeedback associado ao movimento ativo e o uso do Tapping medializando a patela. Além disso, foi comparada a atividade do VM em indivíduos com e sem a "Síndrome da dor femoro-patelar" - SDFP. A maioria dos autores não encontrou, em nenhuma dessas situações, uma atividade preferencial do VM. Conclui-se que não foi evidenciada a recuperação seletiva do VM utilizando-se o movimento ativo voluntário.

[Comprehensive treatment in Achilles tendon rupture]. / Tratamiento integral en la ruptura del tendón calcáneo.

Due to incapacity caused by calcaneal tendon injuries for the reintegration of patients back to their daily activities and/or sparts it is necessary to decrease the time of reinstatement of patients. At present these times have improved by a good surgical technique and an early rehabilitation, and the patient is returned quickly as he sees less disability. It is proposed in this paper a type of surgical treatment and an early rehabilitation program, which have shortened the time of disability and incorporation to their daily activities and sports to eight weeks in 10 patients with Achilles tendon plasty.