Marco Antonio Cavalcanti Garcia

Myofascial Trigger Point Therapy: Laser Therapy and Dry Needling

The aim of the present review is to discuss two forms of treatment for myofascial pain: laser therapy and dry needling. Although studies have reported the deactivation of myofascial trigger points with these two methods, clinical trials demonstrating their efficacy are scarce. The literature reports greater efficacy with the use of laser over dry needling. It has been suggested that improvements in microcirculation through the administration of laser therapy may favor the supply of oxygen to the cells under conditions of hypoxia and help remove the waste products of cell metabolism, thereby breaking the vicious cycle of pain, muscle spasm and further pain. While laser therapy is the method of choice for patients with a fear of needles and healthcare professionals inexperienced with the dry needling technique, further controlled studies are still needed to prove the greater efficacy of this method.

Can the Recording of Motor Potentials Evoked by Transcranial Magnetic Stimulation Be Optimized

Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. Garcia, Marco A.C.; Souza, Victor H.; Vargas, Claudia D.

A novel electromyographic signal simulator for muscle contraction studies

Mathematical simulation has been widely used in biomedical and biological sciences. In the case of the surface electromyographic (SEMG) activity, some models have been proposed aiming to study muscle contraction strategies that are used during different tasks and conditions. Most of SEMG simulators are based on energy modulation of a Gaussian noise. This work proposes a novel simulator in which the user-defined parameters are associated with the motor units (MUs) recruitment and their firing rate. Comparison between the mean spectrum of real SEMG signals collected in isometric contraction of the muscle biceps brachii and the mean spectrum obtained from simulated SEMG signals showed a good agreement, pointing the proposed simulator seems to be capable to generate consistent electromyographic signals in time and frequency domains and that can be used in many studies, in particular in the evaluation of automatic methods aimed to detect muscular contraction.

Comportamento temporal da velocidade de condução de potenciais de ação de unidades motoras sob condições de fadiga muscular

A fadiga muscular, definida como a incapacidade na manutencao de um nivel esperado de forca, tem sido amplamente investigada nas areas clinica e desportiva. Na investigacao dos efeitos da fadiga sobre a regulacao da contracao, a eletromiografia de superficie (SEMG) tem sido uma importante ferramenta eletrodiagnostica, pois diferentes parâmetros de analise podem ser extraidos a partir do sinal de EMG. Dentre estes parâmetros, a velocidade de conducao dos potenciais de acao das unidades motoras (VCPAUMs) tem sido uma variavel importante neste tipo de avaliacao, apesar de comumente ser detectada atraves de tecnicas invasivas, mediante eletrodos de arame ou agulha. Assim, o objetivo deste trabalho foi estimar a VCPAUM atraves da SEMG, avaliando o seu comportamento temporal, em contracoes isometricas realizadas ate a exaustao. Dezoito voluntarios (nove homens e nove mulheres; idade de 25,6 ± 6,8 anos), alunos da EEFD/UFRJ, consentiram em participar do estudo. Os sinais de EMG foram colhidos a partir do musculo biceps braquial direito em tres diferentes niveis (25%, 50 e 75% da carga maxima (CM)), sendo, entao, divididos em tres trechos, correspondentes ao tempo total gasto na tarefa, assim denominados: inicio (T1), meio (T2) e fim (T3). A VCPAUM apresentou reducao temporal durante a passagem pelos trechos (p < 0,0001), comparando todas as cargas. Entretanto, foi observada uma queda abrupta da VCPAUM em T3, principalmente em 50 e 75% da CM (p < 0,05), quando comparadas com a carga de 25% da CM. Os resultados apontam que a VCPAUM sofre modificacoes na medida em que ha uma reducao no pH intracelular, fundamental na permeabilidade da membrana celular e que pode ser decorrente de uma diminuicao no aporte sanguineo, pelo aumento no tempo e no nivel de contracao. Alem disso, a adaptacao no uso da SEMG para a estimativa da VCPAUM mostrou a viabilidade no uso do metodo como ferramenta diagnostica.Muscle fatigue, which is defined as the failure to maintain a required or expected force, has been investigated in both clinical and sports applications. On the investigation of muscle fatigue effects related to muscular control, surface electromyography (SEMG) has been the most common electrodiagnostic method, because some different parameters can be extracted from the EMG signal. Among the parameters, motor units action potential conduction velocity (MUAPCV) has been one of the most important, in spite of being usually detected through indwelling electrodes. Thus, the aim of this work was to estimate MUAPCV through SEMG, detecting its temporal behavior during isometric contractions until exhaustion. Eighteen students from EEFD/UFRJ (9 men and 9 women – mean age 25.6 ± 6.8 years), right handed, consented to participate on this study. The EMG signals were collected from the right biceps braquii muscle through surface electrodes on 3 different levels of isometric contractions (25%, 50 e 75% of maximum load (ML)), which were divided into 3 periods that would define the beginning (P1), the middle (P2), and the end (P3) of the contraction. MUAPCV presented a temporal reduction with fatigue installation, showing a statistical difference among periods (p < 0.0001), comparing all the 3 loads. However, it was observed an abrupt decrease of MUAPCV at P3, mainly for 50 and 75% of ML. The results point out that MUAPCV must be quite sensible to pH reduction and changes on ionic concentrations, defined by blood supply decreases. Furthermore, the adaptations introduced on SEMG to MUAPCV estimation were considered satisfactory, reinforcing this method on electrodiagnostic evaluations.

Influência da distância intereletrodos e da cadência de movimento no domínio da frequência do sinal de EMG de superfície

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% 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.

Efeitos de dois parâmetros antropométricos no comportamento do sinal mecanomiográfico em testes de força muscular

In spite of being a useful method on muscle contraction analysis, few studies have been dedicated to understand how some anthropometrical parameters can interfere in the mechanomyographic (MMG) signal properties. Therefore, the aim of this study was to evaluate the effects of skinfold thickness and arm circumference in the MMG signal behavior in the temporal and frequency domains at different levels of isometric contraction. Twenty-one males (24.9 ± 7.8 years) and 21 females (20.7 ± 2.5 years), all right-handed, participated in this study. Prior to the MMG signals collection, a maximum voluntary contraction test (MVC) was performed to further determine the five levels (20%, 40%, 60%, 80% and 100% of CVM) used during the tests. The two groups performed isometric contractions in the five different levels while MMG signal was collected from the right biceps brachii muscle by a biaxial accelerometer. The root mean square value (RMS), and the median frequency (MF) calculated from the MMG power spectrum were extracted from the MMG signals in X direction, which meant perpendicular to the muscle fibres direction. The bicipital skinfold thickness (BD_DC_B), and the circumference of the right arm, with and without contraction of elbow muscles flexors, have also been measured. The MF presented a decreasing behaviour with the increasing level of contraction; the RMS value followed an increasing pattern, though. There were significant statistical differences (p < 0.05) for the anthropometric variables between groups. It is suggested that the RMS value, differently from the MF, which can be disrupted by the tissues between the muscle and the transducer, should be better correlated with muscle force level.

Interpretation of the mechanisms related to the muscular strength gradation through accelerometry

The aim of this study was to characterize the temporal and spectral components of the muscle contractions in different contraction levels through the accelerometry. Fifteen male and twelve female right-handed individuals participated in this study. The trial was constituted by a maximal workload (MW) test that allowed to determine five different workloads (20%, 40%, 60%, 80% and 100% of MW) which, by its turn, allowed to determine five percentage workloads during the strength test (20%, 40%, 60%, 80%, and 100% of the MW) in isometry during eight seconds each of them. A biaxial accelerometer was put on the muscular abdomen of the right brachii biceps muscle. The mean square root (RMS value), a temporal parameter, and the mean frequency (MFE), a spectral parameter were extracted from the accelerometry signals (MMG signals). Such parameters were analyzed towards the X (perpendicular to the fibers) and Y (parallel to the fibers) directions. Both groups presented a descent behavior pattern of the loaded MFE (Y), and the most accentuated was the female group. The MFE variable (X) in the female group presented similar behavior before the MFE (Y), and it was observed a statistically significant difference only between 20% of the MW and every other workload (p = 0.0022 for 40% and p < 0.0001 for the remaining). The male group did not present any statistically significant difference between workloads. The RMS value (Y) presented an ascent behavior with the workload in both genders, presenting differences between the 20% and 40% workloads of the MW (p = 0.000), and 80% and 100% of the MW (p = 0.01) in the male group. But it was observed no statistically significant difference between workloads in the female group. It is argued that during the muscular contraction, there is non-uniform variations on the fibers diameter, besides the low frequency lateral oscillations. Such information seems to have strong correlation between the type of the fibers, and this could contribute for a better clarification on the possible mechanisms involved in the gradation process of the muscular strength.O objetivo deste estudo foi caracterizar as componentes temporais e espectrais dos abalos musculares em diferentes niveis de contracao muscular atraves da acelerometria. Participaram do estudo 15 individuos do sexo masculino e 12 do feminino, todos destros. O experimento constou de um teste de carga maxima (CM) que permitiu determinar cinco cargas percentuais administradas durante os testes de forca (20%, 40%, 60%, 80% e 100% da CM), em isometria e por oito segundos cada. Um acelerometro biaxial foi colocado sobre o ventre muscular do biceps braquial direito. A raiz media quadratica (valor RMS), um parâmetro temporal, e a frequencia media (FME), um parâmetro espectral, foram extraidas dos sinais de acelerometria (sinal de MMG). Estes parâmetros foram analisados nas direcoes X (perpendicular as fibras) e Y (paralela as fibras). Ambos os grupos apresentaram comportamento decrescente da FME (Y) com a carga, sendo mais pronunciado para o grupo feminino. A variavel FME (X), no grupo feminino, apresentou comportamento semelhante a FME (Y), sendo apenas observada diferenca estatistica significativa entre 20% da CM e todas as demais cargas (p = 0,0022 para 40% e p < 0,0001 para as demais). O grupo masculino nao apresentou diferenca estatistica significativa entre as cargas. O valor RMS (Y) apresentou comportamento crescente com a carga para ambos os grupos, havendo diferencas entre as cargas de 20% e 40% da CM (p = 0,000) e 80%, e 100% da CM (p = 0,01) para o grupo masculino. No entanto, nao foi observada diferenca estatistica significativa entre as cargas para o grupo feminino. Discute-se que durante a contracao muscular ocorrem variacoes nao uniformes do diâmetro da fibra, alem de oscilacoes laterais de baixa frequencia. Estas informacoes parecem ter forte correlacao com a tipagem de fibras, o que poderia contribuir para melhor esclarecer os possiveis mecanismos envolvidos durante o processo de gradacao da forca muscular.

Interpretação dos mecanismos de gradação da força muscular através da acelerometria

The aim of this study was to characterize the temporal and spectral components of the muscle contractions in different contraction levels through the accelerometry. Fifteen male and twelve female right-handed individuals participated in this study. The trial was constituted by a maximal workload (MW) test that allowed to determine five different workloads (20%, 40%, 60%, 80% and 100% of MW) which, by its turn, allowed to determine five percentage workloads during the strength test (20%, 40%, 60%, 80%, and 100% of the MW) in isometry during eight seconds each of them. A biaxial accelerometer was put on the muscular abdomen of the right brachii biceps muscle. The mean square root (RMS value), a temporal parameter, and the mean frequency (MFE), a spectral parameter were extracted from the accelerometry signals (MMG signals). Such parameters were analyzed towards the X (perpendicular to the fibers) and Y (parallel to the fibers) directions. Both groups presented a descent behavior pattern of the loaded MFE (Y), and the most accentuated was the female group. The MFE variable (X) in the female group presented similar behavior before the MFE (Y), and it was observed a statistically significant difference only between 20% of the MW and every other workload (p = 0.0022 for 40% and p < 0.0001 for the remaining). The male group did not present any statistically significant difference between workloads. The RMS value (Y) presented an ascent behavior with the workload in both genders, presenting differences between the 20% and 40% workloads of the MW (p = 0.000), and 80% and 100% of the MW (p = 0.01) in the male group. But it was observed no statistically significant difference between workloads in the female group. It is argued that during the muscular contraction, there is non-uniform variations on the fibers diameter, besides the low frequency lateral oscillations. Such information seems to have strong correlation between the type of the fibers, and this could contribute for a better clarification on the possible mechanisms involved in the gradation process of the muscular strength.O objetivo deste estudo foi caracterizar as componentes temporais e espectrais dos abalos musculares em diferentes niveis de contracao muscular atraves da acelerometria. Participaram do estudo 15 individuos do sexo masculino e 12 do feminino, todos destros. O experimento constou de um teste de carga maxima (CM) que permitiu determinar cinco cargas percentuais administradas durante os testes de forca (20%, 40%, 60%, 80% e 100% da CM), em isometria e por oito segundos cada. Um acelerometro biaxial foi colocado sobre o ventre muscular do biceps braquial direito. A raiz media quadratica (valor RMS), um parâmetro temporal, e a frequencia media (FME), um parâmetro espectral, foram extraidas dos sinais de acelerometria (sinal de MMG). Estes parâmetros foram analisados nas direcoes X (perpendicular as fibras) e Y (paralela as fibras). Ambos os grupos apresentaram comportamento decrescente da FME (Y) com a carga, sendo mais pronunciado para o grupo feminino. A variavel FME (X), no grupo feminino, apresentou comportamento semelhante a FME (Y), sendo apenas observada diferenca estatistica significativa entre 20% da CM e todas as demais cargas (p = 0,0022 para 40% e p < 0,0001 para as demais). O grupo masculino nao apresentou diferenca estatistica significativa entre as cargas. O valor RMS (Y) apresentou comportamento crescente com a carga para ambos os grupos, havendo diferencas entre as cargas de 20% e 40% da CM (p = 0,000) e 80%, e 100% da CM (p = 0,01) para o grupo masculino. No entanto, nao foi observada diferenca estatistica significativa entre as cargas para o grupo feminino. Discute-se que durante a contracao muscular ocorrem variacoes nao uniformes do diâmetro da fibra, alem de oscilacoes laterais de baixa frequencia. Estas informacoes parecem ter forte correlacao com a tipagem de fibras, o que poderia contribuir para melhor esclarecer os possiveis mecanismos envolvidos durante o processo de gradacao da forca muscular.

An alternative approach in muscle fatigue evaluation from the surface EMG signal

The aim of this study was to compare the intervals of time between adjacent zero crossings (ZCI), an alternative frequency-temporal parameter, with the root-mean-square (RMS) value and the median frequency (Fmed) from the surface EMG (sEMG) signal in muscle fatigue analysis. Twenty right-handed volunteers performed isometric contractions of right biceps brachii muscle while sEMG signals were collected from it at three different and arbitrary load levels until fatigue. The mean ZCI presented a significant correlation with Fmed but not with RMS value and it also presented lower coefficients of variation than others. The results pointed that mean ZCI properties can contribute more than Fmed and RMS value on the interpretation of the muscle function under fatigue conditions.

Effect of TMS coil orientation on the spatial distribution of motor evoked potentials in an intrinsic hand muscle

Abstract Previous reports on the relationship between coil orientation and amplitude of motor evoked potential (MEP) in transcranial magnetic stimulation (TMS) did not consider the effect of electrode arrangement. Here we explore this open issue by investigating whether TMS coil orientation affects the amplitude distribution of MEPs recorded from the abductor pollicis brevis (APB) muscle with a bi-dimensional grid of 61 electrodes. Moreover, we test whether conventional mono- and bipolar montages provide representative MEPs compared to those from the grid of electrodes. Our results show that MEPs with the greatest amplitudes were elicited for 45° and 90° coil orientations, i.e. perpendicular to the central sulcus, for all electrode montages. Stimulation with the coil oriented at 135° and 315°, i.e. parallel to the central sulcus, elicited the smallest MEP amplitudes. Additionally, changes in coil orientation did not affect the spatial distribution of MEPs over the muscle extent. It has been shown that conventional electrodes with detection volume encompassing the APB belly may detect representative MEPs for optimal coil orientations. In turn, non-optimal orientations were identified only with the grid of electrodes. High-density electromyography may therefore provide new insights into the effect of coil orientation on MEPs from the APB muscle.