Electrical Activity Of Skeletal Muscles Research Articles

Investigating the spatial resolution of EMG and MMG based on a systemic multi-scale model

While electromyography (EMG) and magnetomyography (MMG) are both methods to measure the electrical activity of skeletal muscles, no systematic comparison between both signals exists. Within this work, we propose a novel in silico model for EMG and MMG and test the hypothesis that MMG surpasses EMG in terms of spatial selectivity, i.e. the ability to distinguish spatially shifted sources. The results show that MMG provides a slightly better spatial selectivity than EMG when recorded directly on the muscle surface. However, there is a remarkable difference in spatial selectivity for non-invasive surface measurements. The spatial selectivity of the MMG components aligned with the muscle fibres and normal to the body surface outperforms the spatial selectivity of surface EMG. Particularly, for the MMG’s normal-to-the-surface component the influence of subcutaneous fat is minimal. Further, for the first time, we analyse the contribution of different structural components, i.e. muscle fibres from different motor units and the extracellular space, to the measurable biomagnetic field. Notably, the simulations show that for the normal-to-the-surface MMG component, the contribution from volume currents in the extracellular space and in surrounding inactive tissues, is negligible. Further, our model predicts a surprisingly high contribution of the passive muscle fibres to the observable magnetic field.

ПОВЫШЕНИЕ УРОВНЯ КООРДИНАЦИОННЫХ СПОСОБНОСТЕЙ У ЮНЫХ БАСКЕТБОЛИСТОВ ПОСРЕДСТВОМ АКТИВАЦИИ МЫШЦ ПОЯСНИЧНО-ТАЗОВОГО КОМПЛЕКСА

The purpose of the research is to compare and analyze the indicators of the total electrical activity of skeletal muscles in young basketball players who trained according to the traditional program and the methodology for the development of coordination abilities, including physical exercises that affect the activity of skeletal muscles of the lumbo-pelvic complex. The differences between the obtained results of physical and technical fitness tests in the compared groups were revealed. Methods and organization of the research. The study involved 24 basketball players aged 13-14 years old, with experience of sports activity from 5 to 6 years. The effectiveness of the use of physical exercises affecting the muscles of the lumbo-pelvic complex was evaluated according to the results of stereotypical tests on the coordination ladder and with static postures. The analysis of the registered skeletal muscles' electrical activity (EMG) was provided by the calculation of its average amplitude. The total EMG electroactivity amplitude was also calculated, which was the sum of the average values of the EMG amplitude of all the studied muscles. The statistical significance of the differences was established by using one-way analysis of variance (ANOVA) with Post-Hoc analysis according to the Newman-Keuls method of the STATISTICA 10 software package. Results and discussion. In the experimental group, under the physical exercises influence, affecting the activity of the skeletal muscles of the lumbo-pelvic complex, there were significant differences compared to the control group. Total electrical activity amplitude of the studied muscles significantly decreases during performing motor actions on the coordination ladder and during holding poses tests which are similar to sports movements motor structure. The results obtained indicate a smaller amount of developing efforts among young basketball players during test exercises in the experimental group. The control group was characterized only by a tendency to decrease the EMG activity of the studied muscles. Significant changes were also observed when assessing the physical and technical fitness of athletes after the study. Conclusion. It was established that the use of physical exercises aimed at the formation of rational activity of the muscles of the lumbo-pelvic complex contributes to more economical motor actions.

Noninvasive Neural Interfacing With Wearable Muscle Sensors: Combining Convolutive Blind Source Separation Methods and Deep Learning Techniques for Neural Decoding

Neural interfacing is essential for advancing our fundamental understanding of movement neurophysiology and for developing human-machine interaction systems. This can be achieved at different levels of the central nervous system (CNS) and peripheral nervous system (PNS); however, direct neural interfaces with brain and nerve tissues face important challenges and are currently limited to clinical cases of severe motor impairment. Recent advances in electronics and signal processing for recording and analyzing surface electromyographic (sEMG) signals allow for a radically new way of establishing human interfaces by reverse engineering the neural information embedded in the electrical activity of skeletal muscles. This approach provides a window into the spiking activity of motor neurons in the spinal cord. In this article, we present a brief overview of neural interfaces and discuss the properties of multichannel sEMG in comparison to other CNS and PNS recording modalities. We then describe signal processing approaches for neural interfacing from sEMG, with a focus on recent breakthroughs in convolutive blind source separation (BSS) methods and deep learning techniques. When combined, these approaches establish unique noninvasive human-machine interfaces for neurotechnologies, with applications in medical devices and large-scale consumer electronics.

Review on Muscle Movement Recording System Using EMG

Electromyography is a neurophysiological technique for examining the electrical activity of skeletal muscles. It occurred from the muscle membrane potential. In a healthy muscle at rest, the spontaneous physiological activity can be a record by End plate potential, insertion activity. EMG recording of the activity of selective cranial nerve muscles is currently included in the intraoperative set during surgical manipulation of the brainstem. When during the process, weak muscles can be detected and treat those muscles to regain their function. EMG is also used to diagnose neuromuscular performance. Its gain is less and frequency response may be broader. Using the EMG technique to record the potential of muscle is an easy way to generate the resting potential of muscle.

Characterization of protein-enriched yogurt and its effects on the lean body weight gain and electrical activity in skeletal muscle of physically active individuals

Protein-enriched yogurts have experienced a growth in marketability in recent years, being demanded especially by consumers interested in increasing their daily apportion of proteins. In this study, the objective was to develop a protein-enriched yogurt and to compare it with a non-enriched yogurt in terms of their physicochemical characteristics, texture, and sensory acceptance after different storage periods and their effects on the lean body weight gain and electrical activity in skeletal muscle of physically active individuals. The supplemented whey protein had a buffering effect on the product, leading to its lower syneresis. Both formulations had similar hardness, indicating that the textural parameters had been retained in the protein-enriched yogurt. Panelists indicated no differences in sensorial attributes between the non-enriched and protein-enriched yogurts, with the sensory characteristics of each product being mainly described by the presence of whey protein and the curdled texture. Consumption of the protein-enriched yogurt did not influence the lean body weight gain by physically active individuals.

Real-Time Hand Gesture Recognition Using Surface Electromyography and Machine Learning: A Systematic Literature Review

Today, daily life is composed of many computing systems, therefore interacting with them in a natural way makes the communication process more comfortable. Human–Computer Interaction (HCI) has been developed to overcome the communication barriers between humans and computers. One form of HCI is Hand Gesture Recognition (HGR), which predicts the class and the instant of execution of a given movement of the hand. One possible input for these models is surface electromyography (EMG), which records the electrical activity of skeletal muscles. EMG signals contain information about the intention of movement generated by the human brain. This systematic literature review analyses the state-of-the-art of real-time hand gesture recognition models using EMG data and machine learning. We selected and assessed 65 primary studies following the Kitchenham methodology. Based on a common structure of machine learning-based systems, we analyzed the structure of the proposed models and standardized concepts in regard to the types of models, data acquisition, segmentation, preprocessing, feature extraction, classification, postprocessing, real-time processing, types of gestures, and evaluation metrics. Finally, we also identified trends and gaps that could open new directions of work for future research in the area of gesture recognition using EMG.

Properties of skeletal muscle in the teleost Sternopygus macrurus are unaffected by short-term electrical inactivity.

Skeletal muscle is distinguished from other tissues on the basis of its shape, biochemistry, and physiological function. Based on mammalian studies, fiber size, fiber types, and gene expression profiles are regulated, in part, by the electrical activity exerted by the nervous system. To address whether similar adaptations to changes in electrical activity in skeletal muscle occur in teleosts, we studied these phenotypic properties of ventral muscle in the electric fish Sternopygus macrurus following 2 and 5 days of electrical inactivation by spinal transection. Our data show that morphological and biochemical properties of skeletal muscle remained largely unchanged after these treatments. Specifically, the distribution of type I and type II muscle fibers and the cross-sectional areas of these fiber types observed in control fish remained unaltered after each spinal transection survival period. This response to electrical inactivation was generally reflected at the transcript level in real-time PCR and RNA-seq data by showing little effect on the transcript levels of genes associated with muscle fiber type differentiation and plasticity, the sarcomere complex, and pathways implicated in the regulation of muscle fiber size. Data from this first study characterizing the acute influence of neural activity on muscle mass and sarcomere gene expression in a teleost are discussed in the context of comparative studies in mammalian model systems and vertebrate species from different lineages.

Extraction of EMG signal in a software compatible format from an online database using WFDB package

Summary The electromyography (EMG) is an electro diagnostic procedure for evaluating the electrical activity of skeletal muscles. It is very difficult to deduce the structure and activation of surrounding muscle tissue from needle-detected EMG signals and thus the extraction of information regarding presence, absence or severity of disease is not possible. The muscle morphology, activation and similarity with measured electromyographic signal features can be explored by comparison with simulated EMG signal. Evaluation of the data using such reference model will provide better understanding of the properties of muscles and their relationship to EMG signals. As the difficulty lies in the non-availability of standard EMG signal, the present work thus focuses on MATLAB implementation of needle detected EMG model introduced by Hamilton-Wright and Stashuk in 2005. The first step of analysis involves conversion of raw EMG signal from .dat format to .txt/.mat format which is achieved by using WFDB (Waveform Database) Software Package. In this research work standard simulated signals available in S002 dataset ( Hamilton-Wright and Stashuk, 2005 ) are extracted and the proposed procedure is presented in a detailed manner.

Shield effect of resistance jumping training on biomechanical parameters in gastrocnemius muscles of diabetic animals

Background Chronic hyperglycemia resulting from diabetes mellitus undertakes several body cells through the formation of advanced glycation end products and activation of the polyol pathway (Brownlle, 2005), promoting reduction of electrical activity in skeletal muscle and the regenerative capacity of its cells, as well as impaired contractility and increased tissue stiffness. In turn, the amplify muscle work during exercise is able to elicit several essential biochemical reactions for hypertrophy, power gain and enhance muscle function (Andersen et al., 1996, 1997, 2004, 2005).

A neuro-fuzzy system for characterization of arm movements.

The myoelectric signal reflects the electrical activity of skeletal muscles and contains information about the structure and function of the muscles which make different parts of the body move. Advances in engineering have extended electromyography beyond the traditional diagnostic applications to also include applications in diverse areas such as rehabilitation, movement analysis and myoelectric control of prosthesis. This paper aims to study and develop a system that uses myoelectric signals, acquired by surface electrodes, to characterize certain movements of the human arm. To recognize certain hand-arm segment movements, was developed an algorithm for pattern recognition technique based on neuro-fuzzy, representing the core of this research. This algorithm has as input the preprocessed myoelectric signal, to disclosed specific characteristics of the signal, and as output the performed movement. The average accuracy obtained was 86% to 7 distinct movements in tests of long duration (about three hours).

Syndecan-4 and β1 integrin are regulated by electrical activity in skeletal muscle: Implications for cell adhesion

Syndecan-4 and integrins are involved in the cell migration and adhesion processes in several cell types. Syndecan-4, a transmembrane heparan sulfate proteoglycan, is associated to focal adhesions in adherent cells and has been described as a marker of satellite cells in skeletal muscle. In this tissue, β1 integrin forms heterodimers with α5 and α6 during myoblast differentiation and with α7 in adult muscle. Here, we show that the levels of these two cell surface membrane molecules are regulated by spontaneous electrical activity during the differentiation of rat primary myoblasts. Syndecan-4 and β1 integrin protein levels decrease after the inhibition of electrical activity using tetrodotoxin (TTX). Syndecan-4 also decreases substantially in denervated rat tibialis anterior muscle. Indirect immunofluorescence analysis shows that syndecan-4 and β1 integrin co-localize with vinculin, a molecular marker of costameres in skeletal muscle myofibers. Co-localization is lost in inactive myotubes adopting a diffuse pattern, suggesting that the costameric organization is disrupted in TTX-treated myotubes. Moreover, the inhibition of spontaneous electrical activity decreases myotube cell adhesion. In summary, this work shows that syndecan-4 and β1 integrin protein levels and their localization in costameric structures are regulated by electrical activity and suggests that this regulatory mechanism influences the adhesion properties of skeletal myotubes during differentiation.

Response of myogenic determination factors to cessation and resumption of electrical activity in skeletal muscle: a possible role for myogenin in denervation supersensitivity.

1. We have prepared probes specific for the chicken myogenic determination genes MyoD, myogenin, myf5, and herculin and have investigated the expression of these genes in response to denervation and acute electrical stimulation in neonate chick muscle, using ribonuclease protection. 2. Upon denervation, herculin mRNA remains essentially unchanged, myf5 transcript levels approximately double, and MyoD message is up-regulated by two- to fivefold. In contrast, the message coding for myogenin, barely detectable in innervated muscle, rises dramatically (approximately 200-fold) on the second day after nerve section; in this respect it resembles acetylcholine receptor (AChR) alpha-, gamma- and delta-subunit mRNAs. Cohybridization experiments reveal that the increase in myogenin mRNA slightly precedes the rise in AChR alpha-subunit message. 3. Electrical stimulation of denervated muscle leads to an immediate decline in myogenin and AChR alpha-subunit mRNAs, with half-lives of less than an hour and approximately 4 hr, respectively; message stability measurements suggest that this is effected through a rapid shutdown of transcription. Messages coding for MyoD, myf5, and herculin decay much more slowly, as a result of slower turnover. 4. Previous experiments have indicated the involvement of a de novo induced (Tsay, H.-J., Neville, C. M., and Schmidt, J., FEBS Lett. 274:69-72, 1990) autocatalytic (Neville, C. M., Schmidt, M., and Schmidt, J., NeuroReport 2:655-657, 1991) transcription factor in the denervation-triggered up-regulation of AChR alpha-subunit expression; the denervation and electrical stimulation experiments reported here are compatible with the notion that myogenin is that factor.

Magnetic resonance imaging and electromyography as indexes of muscle function.

Electromyography (EMG) is commonly used to determine the electrical activity of skeletal muscle during contraction. To date, independent verification of the relationship between muscle use and EMG has not been provided. It has recently been shown that relaxation- (e.g., T2) weighted magnetic resonance images (MRI) of skeletal muscle demonstrate exercise-induced contrast enhancement that is graded with exercise intensity. This study was conducted to test the hypothesis that exercise-induced magnetic resonance (MR) contrast shifts would relate to EMG amplitude if both measures reflect muscle use during exercise. Both MRI and EMG data were collected for separate eccentric (ECC) and concentric (CON) exercise of increasing intensity to take advantage of the fact that the rate of increase and amplitude of EMG activity are markedly greater for CON muscle actions. Seven subjects 30 +/- 2 (SE) yr old performed five sets of 10 CON or ECC arm curls with each of four resistances representing 40, 60, 80, and 100% of their 10 repetition maximum for CON curls. There was 1.5 min between sets and 30 min between bouts (5 sets of 10 actions at each relative resistance). Multiple echo, transaxial T2-weighted MR images (1.5 T, TR/TE 2,000/30) were collected from a 7-cm region in the middle of the arm before exercise and immediately after each bout. Surface EMG signals were collected from both heads of the biceps brachii and the long head of the triceps brachii muscles. CON and ECC actions resulted in increased integrated EMG (IEMG) and T2 values that were strongly related (r = 0.99, P < 0.05) with relative resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

The origin and characterization of the primary signal, noise, and interference sources in the high frequency electrocardiogram

An analysis technique was developed that enabled accurate measurement of the spectral and spatial characteristics of the predominant signal, noise, and interference components in high frequency electrocardiograms. A selective sampling technique, utilizing the isoelectric interval during the T-P segments, enabled the charactetistics of the internally generated noise and external interference to be obtained independently of the heart signal. Using this sampling technique, it was found that the electrical activity of skeletal muscles was the major source of noise in the high frequency electrocardiogram. The amounts of skdetal muscle noise present in the high frequency electrocardiograms of resting patients were measured quantitatively through the use of anesthetics and muscle relaxant drugs. In the normal resting state, the electrical activity of skeletal muscles contributed up to 15 dB of random noise to the spectra of waveforms generated by the electrical activity of the heart. Moderate, voluntary contraction of small groups of skeletal muscles increased their electrical output by 15 to 20 dB. Spectral analysis of high frequency electrocardiograms indicated that a dynamic range of approximately 66 dB is requized to adequately measure the signal and noise components present. Power spectra of high frequency electrocardiograms indicated that the 60-Hz power lines were the major source of interference Harmonics of the 60-Hz power line added significant interference components at frequencies as high as 1 kHz. The magnitude-squared coherence function between pairs of electrocardiographic leads, in conjunction with segment sampling and analysis techniques, was used to measure the spatial coherence of waveforms from electrical source associated with heart and skeletal muscle activity. The high values of spatial coherence of heart signal waveforms indicated that the body spatial transfer functions for electrical sources associated with heart activity acted as linear, noiseless transmission channels. The low spatial coherence of the waveforms generated by the electrical activity of skeletal muscles indicated that the body spatial transfer functions for electrical sources associated with skeletal muscle activity acted as noisy (nondeterministic) transmission channels. The spatial coherence of isoelectric interval waveforms was inversely proportional to both the distance between measurement sites and the amount of skeletal muscle activity.

Motor endplate alterations in schizophrenic patients.

NEUROMUSCULAR pathology has been described in a variety of mentally ill patients, primarily those suffering from schizophrenia or the affective psychosis. Some psychotic patients have increased electrical activity of skeletal muscle at rest1, abnormal electromyograms2, perform poorly on various tests of neuromuscular coordination3, have elevated serum creatine phosphokinase activity during an acute psychotic episode4 and show an increased incidence of morphological abnormalities of skeletal muscle5,6. Such studies have suggested that there may be an alteration of muscle innervation in such patients. We have previously reported that psychotic patients have an increased incidence of branching and sprouting of intramuscular nerve twigs6. We now report significant alterations in the morphology of the nerve terminals at the motor endplate in psychotic patients. This suggests that there may be an abnormality of transmission at neuromuscular synapses in some psychotic patients.

Effect of pH of the external solution on posttetanic hyperpolarization of the denuded nerve

The background electrical activity of skeletal muscles, autonomic nerves and several brain structures was recorded in cats under acute and chronic conditions. The spectrum-correlation analysis showed that the spatial synchronization within the range of 25 to 35 Hz between autonomic nerves and brain formations (established in previous experiments) comprises the skeletal muscles as well. One of the possible mechanisms by which the rhythm of 25 to 35 Hz facilitates activity in the nervous system is suggested to be related to the frequency potentiation of the synaptic transmission.

The part played by the skeletal muscles in the changes in gaseous exchange in hyper- and hypothermia

Gaseous exchange and electrical activity of skeletal muscle were studied in white rats at rest. The rectal temperature varied between 38.5°–40° and 18–11°. It was shown that when the body temperature was high, gaseous exchange was minimal and there was no electrical activity in the muscles. When the body temperature fell, both gaseous exchange and muscular electrical activity first rose and then fell. At very low body temperatures, only the muscles of the proximal parts of the body continued to manifest some electrical activity.

Rhythmic Electrical Activity of Skeletal Muscle in the Salamander and Its Modification by Convulsant and Anticonvulsant Drugs

Rhythmic Electrical Activity of Skeletal Muscle in the Salamander and Its Modification by Convulsant and Anticonvulsant Drugs

Electrical activity of skeletal muscle of normal and acclimatized rats on exposure to cold.

Electrical activity of skeletal muscle of normal and acclimatized rats on exposure to cold.