Human Muscle Activity Research Articles

Haptics Electromyography Perception and Learning Enhanced Intelligence for Teleoperated Robot

Due to the lack of transparent and friendly human-robot interaction (HRI) interface, as well as various uncertainties, it is usually a challenge to remotely manipulate a robot to accomplish a complicated task. To improve the teleoperation performance, we propose a new perception mechanism by integrating a novel learning method to operate the robots in the distance. In order to enhance the perception of the teleoperation system, we utilize a surface electromyogram signal to extract the human operator's muscle activation. As a response to the changes in the external environment, as sensed through haptic and visual feedback, a human operator naturally reacts with various muscle activations. By imitating the human behaviors in task execution, not only motion trajectory but also arm stiffness adjusted by muscle activation, it is expected that the robot would be able to carry out the repetitive tasks autonomously or uncertain tasks with improved intelligence. To this end, we develop a robot learning algorithm based on probability statistics under an integrated framework of the hidden semi-Markov model (HSMM) and the Gaussian mixture method. This method is employed to obtain a generative task model based on the robot's trajectory. Then, Gaussian mixture regression based on HSMM is applied to correct the robot trajectory with the reproduced results from the learned task model. The execution procedures consist of a learning phase and a reproduction phase. To guarantee the stability, immersion, and maneuverability of the teleoperation system, a variable gain control method that involves electromyography (EMG) is introduced. Experimental results have demonstrated the effectiveness of the proposed method.

Omega-3 Fatty Acid-Derived Resolvin D2 Regulates Human Placental Vascular Smooth Muscle and Extravillous Trophoblast Activities.

Omega-3 fatty acids are important to pregnancy and neonatal development and health. One mechanism by which omega-3 fatty acids exert their protective effects is through serving as substrates for the generation of specialized pro-resolving lipid mediators (SPM) that potently limit and resolve inflammatory processes. We recently identified that SPM levels are increased in maternal blood at delivery as compared to umbilical cord blood, suggesting the placenta as a potential site of action for maternal SPM. To explore this hypothesis, we obtained human placental samples and stained for the SPM resolvin D2 (RvD2) receptor GPR18 via immunohistochemistry. In so doing, we identified GPR18 expression in placental vascular smooth muscle and extravillous trophoblasts of the placental tissues. Using in vitro culturing, we confirmed expression of GPR18 in these cell types and further identified that stimulation with RvD2 led to significantly altered responsiveness (cytoskeletal changes and pro-inflammatory cytokine production) to lipopolysaccharide inflammatory stimulation in human umbilical artery smooth muscle cells and placental trophoblasts. Taken together, these findings establish a role for SPM actions in human placental tissue.

Changes in motoneuron excitability during voluntary muscle activity in humans with spinal cord injury.

The excitability of resting motoneurons increases following spinal cord injury (SCI). The extent to which motoneuron excitability changes during voluntary muscle activity in humans with SCI, however, remains poorly understood. To address this question, we measured F waves by using supramaximal electrical stimulation of the ulnar nerve at the wrist and cervicomedullary motor-evoked potentials (CMEPs) by using high-current electrical stimulation over the cervicomedullary junction in the first dorsal interosseous muscle at rest and during 5 and 30% of maximal voluntary contraction into index finger abduction in individuals with chronic cervical incomplete SCI and aged-matched control participants. We found higher persistence (number of F waves present in each set) and amplitude of F waves at rest in SCI compared with control participants. With increasing levels of voluntary contraction, the amplitude, but not the persistence, of F waves increased in both groups but to a lesser extent in SCI compared with control participants. Similarly, the CMEP amplitude increased in both groups but to a lesser extent in SCI compared with controls. These results were also found at matched absolutely levels of electromyographic activity, suggesting that these changes were not related to decreases in voluntary motor output after SCI. F-wave and CMEP amplitudes were positively correlated across conditions in both groups. These results support the hypothesis that the responsiveness of the motoneuron pool during voluntary activity decreases following SCI, which could alter the generation and strength of voluntary muscle contractions.NEW & NOTEWORTHY How the excitability of motoneurons changes during voluntary muscle activity in humans with spinal cord injury (SCI) remains poorly understood. We found that F-wave and cervicomedullary motor-evoked potential amplitude, outcomes reflecting motoneuronal excitability, increased during voluntary activity compared with rest in SCI participants but to a lesser extent that in controls. These results suggest that the responsiveness of motoneurons during voluntary activity decreases following SCI, which might affect functionally relevant plasticity after the injury.

Robot mobile control based on three EMG signals using an artificial neural network

The EMG signals can be produced from the human muscle activity. This paper explains the control system of the robot mobile which uses the EMG signal from three muscles contraction such as the jaw muscles, the right arm muscles, and the left arm muscles. The peak values of the EMG signal was used as the input to the ANN system using the Backpropagation algorithm, and it produces the output which has nine target conditions; the forward, then turn right and then turn left where each of them has the variations such as the slow, the medium and the fast. The ANN has been trained with 270 of the training data, and it has been tested with 135 of the testing data from 15 respondents who performed muscle contraction activities. Based on the test result, there are only two unrecognizable data with the rate of the system accuracy is 98.52%. The movements of the robot mobile can be controlled based on the recognized movement patterns with the specified target conditions.

Contractile activity-specific transcriptome response to acute endurance exercise and training in human skeletal muscle.

Reduction in daily activity leads to dramatic metabolic disorders, while regular aerobic exercise training is effective for preventing this problem. The purpose of this study was to identify genes that are directly related to contractile activity in human skeletal muscle, regardless of the level of fitness. Transcriptome changes after the one-legged knee extension exercise in exercised and contralateral nonexercised vastus lateralis muscle of seven men were evaluated by RNA-seq. Transcriptome change at baseline after 2 mo of aerobic training (5/wk, 1 h/day) was evaluated as well. Postexercise changes in the transcriptome of exercised muscle were associated with different factors, including circadian oscillations. To reveal transcriptome response specific for endurance-like contractile activity, differentially expressed genes between exercised and nonexercised muscle were evaluated at 1 and 4 h after the one-legged exercise. The contractile activity-specific transcriptome responses were associated only with an increase in gene expression and were regulated mainly by CREB/ATF/AP1-, MYC/MAX-, and E2F-related transcription factors. Endurance training-induced changes (an increase or decrease) in the transcriptome at baseline were more pronounced than transcriptome responses specific for acute contractile activity. Changes after training were associated with widely different biological processes than those after acute exercise and were regulated by different transcription factors (IRF- and STAT-related factors). In conclusion, adaptation to regular exercise is associated not only with a transient (over several hours) increase in expression of many contractile activity-specific genes, but also with a pronounced change (an increase or decrease) in expression of a large number of genes under baseline conditions.

ПОШУК САЙТУ ЗВ'ЯЗУВАННЯ КАЛІКС [4] АРЕНІВ ІЗ КІНАЗОЮ ЛЕГКИХ ЛАНЦЮГІВ МІОЗИНУ МЕТОДОМ МОЛЕКУЛЯРНОЇ ДИНАМІКИ

Disruptions of the functional activity of human smooth muscle are associated with a significant number of pathological conditions of the human body. The myosin light-chain kinase is the key enzyme of the signaling cascade of neurohumoral signals in smooth muscle cells. Especially it is important in the long-term tonic contraction. Disruption of its kinase activity can lead to a weakening of the intercellular interaction of the epithelial and endothelial cells, disruption of functioning of the intestinal smooth muscles and vessels, complication of labor activity. At the moment the search for effectors of this enzyme is being carried out. The problem is that most drugs are removed at the general body level due to toxic effects on other tissues (organs) or adverse chemical and physical properties. Such substances require adapters (carriers) devoid of these defects and inert in vivo. The most promising are calixarenes. In this study, the molecular dynamics method was used to determine the stability of the calix [4] arenetetrazulphate complex and the myosin light-chain kinase catalytic domain. Initially, by means of docking, the most favorable position of calixaren was determined; it turned out to be a catalytic kinase pocket. After that, the molecular-dynamic experiment was conducted to determine the energy of interaction. It turned out that the total energy of the interaction is about -300 cJ/mol. This indicates the high stability of the complex. Due the location of the ligand, its effect on the enzymatic activity of the kinase can be assumed, therefore, the use of this calixarene as a drug delivery system seems inappropriate.

Analysis of Stem Cells and Their Activity in Human Skeletal Muscles by Immunohistochemistry.

Immunohistochemistry (IHC) is a frequently used technique in life science and in clinic diagnostic. IHC is a high precision method to localize different cell types or their expression in tissue. Over the years, different approaches of IHC have emerged, and the technique has become more and more sophisticated. However, the principles still remains: the inherent and spontaneous non-covalent interaction between an antibody and (hypothetical) any target of interest. That means, using this technique allows you to analyze a wide range of histological tissues (muscles, organs, neurons, etc.) from humans or animals under the microscope. Literally, IHC makes the invisible to the human eye clearly visible. In this chapter, we present an approach how to analyze human skeletal muscle tissue for content and activity of muscle stem cells, termed satellite cells.

Hydroxysafflor yellow A (HSYA) targets the platelet-activating factor (PAF) receptor and inhibits human bronchial smooth muscle activation induced by PAF.

Hydroxysafflor yellow A (HSYA) is the main active ingredient of edible plant safflower. HSYA has demonstrated anti-inflammatory effects. The inflammatory response is the key mechanism responsible for asthma, and the pro-inflammatory platelet-activating factor (PAF) is known to play a role in the pathology of bronchial asthma. In this study, we stimulated human bronchial smooth muscle cells (HBSMCs) with PAF and examined the effects of HSYA on the resulting asthma-related process. PAF stimulation induced HBSMC activation, induced proliferation, increased expression of the pro-inflammatory cytokines interleukin (IL)-6, IL-1β, and tumor necrosis factor-α, and activated asthma-related signaling pathways. All these effects were significantly inhibited by treatment with HSYA (9, 27, 81 μmol L-1). The effects of HSYA were prevented by the addition of a PAF receptor (PAFR) antagonist or by PAFR gene silencing with small interfering RNA. These results suggest that HSYA may inhibit PAF-induced activation of HBSMCs by targeting the PAFR. Overall, these findings provide evidence that HSYA can be applied as a potential therapeutic agent in the treatment of bronchial asthma.

Decisions are expedited through multiple neural adjustments spanning the sensorimotor hierarchy

When decisions are made under speed pressure, “urgency” signals elevate neural activity toward action-triggering thresholds independent of the sensory evidence, thus incurring a cost to choice accuracy. While urgency signals have been observed in brain circuits involved in preparing actions, their influence at other levels of the sensorimotor pathway remains unknown. We used a novel contrast-comparison paradigm to simultaneously trace the dynamics of sensory evidence encoding, evidence accumulation, motor preparation, and muscle activation in humans. Results indicate speed pressure impacts multiple sensorimotor levels but in crucially distinct ways. Evidence-independent urgency was applied to cortical action-preparation signals and downstream muscle activation, but not directly to upstream levels. Instead, differential sensory evidence encoding was enhanced in a way that partially countered the negative impact of motor-level urgency on accuracy, and these opposing sensory-boost and motor-urgency effects had knock-on effects on the buildup and pre-response amplitude of a motor-independent representation of cumulative evidence.

Antagonism of the D2 dopamine receptor enhances tremor but reduces voluntary muscle activation in humans

Neural circuits that comprise the indirect pathway in the basal ganglia have been implicated in tremor genesis, and possibly play a role in the voluntary activation of muscles. However, an absence of in vivo human studies that target striatal D2 dopamine receptors of the indirect pathway have prevented causal links being made between the D2 receptor and motor control. Healthy individuals ingested 3 mg of the competitive D2 antagonist haloperidol in a double-blinded, placebo-controlled, two-way, cross-over study. Two experiments were performed to examine involuntary and voluntary movement. The first experiment (n = 10) assessed time- and frequency-domain measures of force tremor during isometric elbow flexions, and the second experiment (n = 8) examined voluntary activation of the elbow flexors during unfatigued and fatigued maximum contractions. Blockade of the D2 receptor had no effect on tremor frequency, but increased the amplitude of force variability and 8–12 Hz power during moderate intensity isometric elbow flexions. These findings provide direct evidence that D2 receptors relate to physiological tremor generation during muscle contractions, whereby the gain of tremor is increased after D2 antagonism. The ability to voluntarily activate the elbow flexors was compromised under both non-fatigued and fatigued conditions. Consequently, the duration that maximum contractions could be sustained was reduced with D2 antagonism. These results provide further support that the D2 receptor has a critical role in skeletal muscle activation, where central fatigue is exacerbated by enhancing activity of the indirect basal ganglia pathway during maximum muscle contractions.

Determining Best Window Size for an Improved Gabor Transform in EMG Signal Analysis

Electromyography EMG is a standout amongst the most regularly utilized tools to study human muscle condition. But due to the intricate attributes of the EMG itself, time-frequency distributions such as Gabor transform and spectrogram are more preferred than the simpler time distribution and frequency distribution. These techniques have been broadly utilized as it can provide both time and frequency information. However, both techniques have a fix window size for all frequency values, thus there exist a problem of determination of the window size, where excessively limit window and too wide window, will result in poor frequency resolution and time resolution, respectively. Along these lines, the point of this study is to choose the best window size so as to be utilized with Gabor transform to screen human muscle activity during core-lifting task. Four electrodes were placed on the right and left biceps brachii, and left and right erector spinae. In this study, the results of five acceptable window sizes (300, 400, 430, 450 and 520) were shown, despite the fact that other window sizes were also tested. Three criteria have been considered during the determination of the best window size, which are good time resolution, good frequency resolution, and high accuracy. Results demonstrate that window size of 450 is the best compared to others. As an additional analysis, the result is compared to a spectrogram and it can be seen that Gabor transform is better, as it has the flexibility in choosing the window size, thus affects the resolution and accuracy.

EMG-Based Spasticity Robotic Arm Forupper Arm Fatigue Identification

Electromyogram (EMG) signal reflect the electrical activity of human muscle and contains information about the structure of muscle. Furthermore, motor unit action potential (MUAP) is the results from spatial and temporal summation of difference muscle fibers of a single motor. The EMG signal results, in turn is from the summation of different MUAPs which are sufficiently near the recording electrode. EMG signal can identify the differences between signals from bicep, triceps and forearms during exercise. Raw data from the experiment is vital to assist physiotherapy to understand when the subject fatigue of noise high pick signal during rehabilitation. Several normal subjects were selected to perform experiments to understand the pattern of fatigue in early state, middle stage and last stage of exercises.

Revisão sistemática: dieta cetogênica e suas implicações na performance

Introdução: O glicogênio é fonte energética para ações musculares. Dietas ricas em carboidratos permitem o armazenamento e disponibilização desse glicogênio. As dietas cetogênicas, apesar de reduzir os estoques de glicogênio, permitem que o organismo utilize como substrato a gordura corporal. Objetivamos identificar se a mudança alimentar pode influenciar na performance. Metodologia: Trata-se de uma revisão sistemática na base de dados do PubMed. Resultados: Foram encontrados 100 estudos. Cinco foram selecionados para compor este artigo. Conclusão: Esse tipo de intervenção dietética permite a perda de gordura corporal, mantendo a estrutura muscular construída pelo treinamento, sem prejudicar a performance.

Surface electromyography can quantify temporal and spatial patterns of activation of intrinsic human foot muscles

Intrinsic foot muscles (IFM) are a crucial component within the human foot. Investigating their functioning can help understand healthy and pathological behaviour of foot and ankle, fundamental for everyday activities. Recording muscle activation from IFM has been attempted with invasive techniques, mainly investigating single muscles. Here we present a novel methodology, to investigate the feasibility of recording physiological surface EMG (sEMG) non-invasively and quantify patterns of activation across the whole plantar region of the foot. sEMG were recorded with a 13 × 5 array from the sole of the foot (n = 25) during two-foot stance, two-foot tiptoe and anterior/posterior sways. Physiological features of sEMG were analysed. During anterior/posterior epochs within the sway task, sEMG patterns were analysed in terms of signal amplitude (intensity) and structure (Sample Entropy) distribution, by evaluating the centre of gravity (CoG) of each topographical map. Results suggest signals are physiological and not affected by loading. Both amplitude and sample entropy CoG coordinates were grouped in one region and overlapped, suggesting that the region with highest amplitude corresponds with the most predictable signal. Therefore, both spatial and temporal features of IFM activation may be recorded non-invasively, providing opportunity for more detailed investigation of IFM function in healthy and patient populations.

Development of a human head and neck muscle activation control model based on BPNN

With the development of vehicle active safety technology and its combination with passive safety technologies, there is a need for an updated tool to assess the performance of vehicle safety systems in both the in-crash and pre-crash phases. Consequently, developing human body models with active muscles is critical to achieve improved bio-fidelity simulation results to evaluate the effects of safety systems. In the present study, an innovative human active muscle control model based on a back-propagation neural network (BPNN) controller was developed, and the active muscle response was modelled using a feedback control strategy with the BPNN algorithm implemented in a human head and neck Sim Mechanics model. The BPNN controller was used to dynamically control the muscle activation level, the most complicated and essential factor in active muscle force calculation based on the Hill equation. Then, the active muscle control model was evaluated by simulating the human response in volunteer sled tests. The results validated the proposed active muscle control method as successful and easily realized. Achieving muscle active control would further improve the bio-fidelity of the human body model.

Muscle Activity‐Driven Green‐Oriented Random Number Generation Mechanism to Secure WBSN Wearable Device Communications

Wireless body sensor networks (WBSNs) mostly consist of low‐cost sensor nodes and implanted devices which generally have extremely limited capability of computations and energy capabilities. Hence, traditional security protocols and privacy enhancing technologies are not applicable to the WBSNs since their computations and cryptographic primitives are normally exceedingly complicated. Nowadays, mobile wearable and wireless muscle‐computer interfaces have been integrated with the WBSN sensors for various applications such as rehabilitation, sports, entertainment, and healthcare. In this paper, we propose MGRNG, a novel muscle activity‐driven green‐oriented random number generation mechanism which uses the human muscle activity as green energy resource to generate random numbers (RNs). The RNs can be used to enhance the privacy of wearable device communications and secure WBSNs for rehabilitation purposes. The method was tested on 10 healthy subjects as well as 5 amputee subjects with 105 segments of simultaneously recorded surface electromyography signals from their forearm muscles. The proposed MGRNG requires only one second to generate a 128‐bit RN, which is much more efficient when compared to the electrocardiography‐based RN generation algorithms. Experimental results show that the RNs generated from human muscle activity signals can pass the entropy test and the NIST random test and thus can be used to secure the WBSN nodes.

Evaluation of the human muscle activity mimic types all mechanics power assist device

Evaluation of the human muscle activity mimic types all mechanics power assist device

Increased autophagy signaling but not proteasome activity in human skeletal muscle after prolonged low-intensity exercise with negative energy balance.

Little is known about the molecular regulation of skeletal muscle protein turnover during exercise in field conditions where energy is intake inadequate. Here, 17 male and 7 female soldiers performed an 8 days long field‐based military operation. Vastus lateralis muscle biopsies, in which autophagy, the ubiquitin–proteasome system, and the mTORC1 signaling pathway were studied, were collected before and after the operation. The 187 h long operation resulted in a 15% and 29% negative energy balance as well as a 4.1% and 4.6% loss of body mass in women and men, respectively. After the operation protein levels of ULK1 as well as the phosphorylation of ULK1Ser317 and ULK1Ser555 had increased by 11%, 39%, and 13%, respectively, and this was supported by a 17% increased phosphorylation of AMPKThr172 (P < 0.05). The LC3b‐I/II ratio was threefold higher after compared to before the operation (P < 0.05), whereas protein levels of p62/SQSTM1 were unchanged. The β1, β2, and β5 activity of the proteasome and protein levels of MAFbx did not change, whereas levels of MuRF‐1 were slightly reduced (6%, P < 0.05). Protein levels and phosphorylation status of key components in the mTORC1 signaling pathway remained at basal levels after the operation. Muscle levels of glycogen decreased from 269 ± 12 to 181 ± 9 mmol·kg dry·muscle−1 after the exercise period (P < 0.05). In conclusion, the 8 days of field‐based exercise resulted in induction of autophagy without any increase in proteasome activity or protein ubiquitination. Simultaneously, the regulation of protein synthesis through the mTORC1 signaling pathway was maintained.

Robot adaptation to human physical fatigue in human–robot co-manipulation

In this paper, we propose a novel method for human---robot collaboration, where the robot physical behaviour is adapted online to the human motor fatigue. The robot starts as a follower and imitates the human. As the collaborative task is performed under the human lead, the robot gradually learns the parameters and trajectories related to the task execution. In the meantime, the robot monitors the human fatigue during the task production. When a predefined level of fatigue is indicated, the robot uses the learnt skill to take over physically demanding aspects of the task and lets the human recover some of the strength. The human remains present to perform aspects of collaborative task that the robot cannot fully take over and maintains the overall supervision. The robot adaptation system is based on the Dynamical Movement Primitives, Locally Weighted Regression and Adaptive Frequency Oscillators. The estimation of the human motor fatigue is carried out using a proposed online model, which is based on the human muscle activity measured by the electromyography. We demonstrate the proposed approach with experiments on real-world co-manipulation tasks: material sawing and surface polishing.

Increased autophagy signalling but not proteasome activity in human skeletal muscle after prolonged low-intensity exercise with negative energy balance

Purpose: Little is known about the molecular regulation of skeletal muscle protein turnover during exercise in field conditions were energy intake often is inadequate. To further investigate, 24 male and female soldiers performed an 8 day long field based military operation.