EMG Measurements Research Articles

Concurrent Contribution of Co-contraction to Error Reduction during Dynamic Adaptation of the Wrist.

MRI-compatible robots provide a means of studying brain function involved in complex sensorimotor learning processes, such as adaptation. To properly interpret the neural correlates of behavior measured using MRI-compatible robots, it is critical to validate the measurements of motor performance obtained via such devices. Previously, we characterized adaptation of the wrist in response to a force field applied via an MRI-compatible robot, the MR-SoftWrist. Compared to arm reaching tasks, we observed lower end magnitude of adaptation, and reductions in trajectory errors beyond those explained by adaptation. Thus, we formed two hypotheses: that the observed differences were due to measurement errors of the MR-SoftWrist; or that impedance control plays a significant role in control of wrist movements during dynamic perturbations. To test both hypotheses, we performed a two-session counterbalanced crossover study. In both sessions, participants performed wrist pointing in three force field conditions (zero force, constant, random). Participants used either the MR-SoftWrist or the UDiffWrist, a non-MRI-compatible wrist robot, for task execution in session one, and the other device in session two. To measure anticipatory co-contraction associated with impedance control, we collected surface EMG of four forearm muscles. We found no significant effect of device on behavior, validating the measurements of adaptation obtained with the MR-SoftWrist. EMG measures of co-contraction explained a significant portion of the variance in excess error reduction not attributable to adaptation. These results support the hypothesis that for the wrist, impedance control significantly contributes to reductions in trajectory errors in excess of those explained by adaptation.

Electromyography detection of muscle response in musculus quadriceps femoris of elite volleyball players on different training stimuli

The aim of this research was the detection of bioelectric potential i, generated in the muscle cells of volleyball players and muscle stimulation, using the electromyography method, during different training stimuli. A set of variables was applied for EMG measurement: measuring bioelectrical activity prior to any training stimulus, measuring after the coordination exercises (athletic - coordination and SAQ exercises, measuring after the proprioception exercises (balance maintaining at the profiboard for 1 minute) and measuring after a thrust at the leg press and a half squat in the maximum strain regime. The study was conducted with 16 players from Serbia National Volleyball Team, Champion of Europe. For the results analysis at the multivariate level, we used the discriminant descriptive data analysis method. After the results analysis, which shows the differences of the measurement values before and after the stimuli and after the proprioception variables at the multivariate level, it can be stated that there are statistically significant differences (p= 0.018311). The conclusion is that the coordination exercises do not produce the acute effect of increasing the muscle bioelectrical activity, Power and strength exercises created statistically significant change in the bioelectrical activity and as such they justify their role in the warming phase, i.e. the preparation of the neuromusculature apparatus for the work with the additional load (weights) in the specific conditions and the requirements of the training process of the elite volleyball players. Proprioceptive exercises created statistically significant difference in the bioelectrical activity, which primarily justifies their preventive and rehabilitative role in the training process and specifically programmed exercise.

Three-Electrode Double-Differential Biopotential Amplifier for Surface EMG Measurements

Three-Electrode Double-Differential Biopotential Amplifier for Surface EMG Measurements

Effects of simulated hypo-gravity on lower limb kinematic and electromyographic variables during anti-gravitational treadmill walking.

Introduction: This study investigated kinematic and EMG changes in gait across simulated gravitational unloading levels between 100% and 20% of normal body weight. This study sought to identify if each level of unloading elicited consistent changes-particular to that percentage of normal body weight-or if the changes seen with unloading could be influenced by the previous level(s) of unloading. Methods: 15 healthy adult participants (26.3 2.5years; 53% female) walked in an Alter-G anti-gravity treadmill unloading system (mean speed: 1.49 mph) for 1min each at 100%, 80%, 60%, 40% and 20% of normal body weight, before loading back to 100% in reverse order. Lower-body kinematic data were captured by inertial measurement units, and EMG data were collected from the rectus femoris, biceps femoris, medial gastrocnemius, and anterior tibialis. Data were compared across like levels of load using repeated measures ANOVA and statistical parametric mapping. Difference waveforms for adjacent levels were created to examine the rate of change between different unloading levels. Results: This study found hip, knee, and ankle kinematics as well as activity in the rectus femoris, and medial gastrocnemius were significantly different at the same level of unloading, having arrived from a higher, or lower level of unloading. There were no significant changes in the kinematic difference waveforms, however the waveform representing the change in EMG between 100% and 80% load was significantly different from all other levels. Discussion: This study found that body weight unloading from 100% to 20% elicited distinct responses in the medial gastrocnemius, as well as partly in the rectus femoris. Hip, knee, and ankle kinematics were also affected differentially by loading and unloading, especially at 40% of normal body weight. These findings suggest the previous level of gravitational load is an important factor to consider in determining kinematic and EMG responses to the current level during loading and unloading below standard g. Similarly, the rate of change in kinematics from 100% to 20% appears to be linear, while the rate of change in EMG was non-linear. This is of particular interest, as it suggests that kinematic and EMG measures decouple with unloading and may react to unloading uniquely.

Chapter 10 - Neuromuscular electrodiagnosis

The electrodiagnostic (EDX) study is an extension of the clinical examination, which means that the clinical features dictate the initial nerve conduction studies (NCS) performed. However, once the EDX study is started, it continues in an independent manner, meaning that the initial NCS findings dictate the subsequent studies performed. Because competent EDX study performance requires considerable knowledge (and special training), it is not possible to convey all of the basic and advanced concepts in a single chapter. Nonetheless, the most important concepts are easily conveyed by a discussion limited to EDX-pertinent anatomical, physiological, pathological, pathophysiological, and basic electrical concepts. The focus of this chapter will be on the standard NCS and needle EMG measurements made during EDX studies and their significance with regard to lesion localization and characterization. Because the most challenging portion of EDX study is motor unit action potential analysis, this topic is more extensively reviewed. The utility of the sensory NCS for identifying focal axon loss, the utility of the motor NCS for screening long nerve segments for focal demyelination and for determining lesion severity, and the utility of the needle EMG for confirming the NCS findings, better defining lesion localization, and identifying the temporal features (e.g., chronicity) and rate of progression of the lesion are also reviewed.

Are proximal and distal neuromuscular parameters able to predict hip and knee frontal plane kinematics during single-leg landing?

ObjectiveTo determine if proximal and distal neuromuscular parameters (EMG amplitude and median frequency – MDF) can predict frontal plane kinematics during single-leg landing. Study designCross sectional study. SettingLaboratory. ParticipantsFifteen participants (7 female) performed six single-leg landings with measures of frontal plane kinematics and EMG obtained 230 ms after first foot contact, totalizing 90 landings. Main outcome measures(i) 2D hip adduction [hip ADD] and knee frontal plane projection angle [knee FPPA]; (ii) EMG amplitude and MDF of gluteus medius [GMed], tensor fascia latae [TFL], peroneus longus [PL] and tibialis anterior [TA]. ResultsWe observed that MDF of TA was a significant predictor of hip ADD (p = 0.037; β = −0.049 Hz; R2c = 0.30). Also, MDF of PL was significant predictor of knee FPPA (p = 0.043; β = 0.042 Hz; R2c = 0.37). Hip muscles and EMG amplitude parameters were not considered predictors of frontal plane kinematics. ConclusionThe firing frequency of ankle muscles predicted the variance of hip and knee frontal plane kinematics during single-leg landing.

Can the subject reliably reproduce maximum voluntary contraction of temporalis and masseter muscles in surface EMG?

ABSTRACT Objective To evaluate the repeatability of the surface EMG variables of myoelectric signals from the masseter and temporalis muscles according to three methods to induce maximum voluntary contraction (MVC) in healthy adults. Methods Thirty healthy young subjects performed the following three MVC tasks three times each in three sessions on the same day without replacing surface electrodes: clenching the teeth (MVCIC) and biting down on two cotton rolls bilaterally with the posterior teeth (MVCBP) or first molars (MVCB6). Results The intra-class correlation coefficient (ICC) of the amplitudes during the three MVC tasks ranged from 65 to 79%. The ICCs of the spectral variables ranged from 78 to 86%. The ICCs of the asymmetry index of the masseter ranged from 77 to 86%, and those of the activity index ranged from 68 to 90%. Conclusion The surface EMG measurements according to the three MVC methods exhibited good to excellent reproducibility.

Optimal prototype design of dry textile electrode-based compression pants for surface electromyography measurements

PurposeTo provide guidelines for the development of textile electrode compression pants that collect reliable signals during surface electromyography (sEMG) measurements and maintain a comfortable level of pressure.Design/methodology/approachTo increase skin adhesion, 12 textile electrode bands for biceps brachii were prepared according to a combination of variables, namely, the type of the textile electrode, the pressure level and the presence or absence of an electrolyte. The dry textile electrode adopted herein was developed in terms of the size and material of the contact area, and a new electrode design was proposed. After examining the optimal design conditions by measuring the sEMGs during isometric exercise of the biceps brachii, prototype pants were designed based on the design variables that gave the most promising evaluation results. The completed prototype pants were verified through isometric thigh muscle exercises.FindingsIt was confirmed that the textile electrode was capable of EMG measurement with an excellent signal quality. Upon considering the comfort of wearing the device and the cost efficiency of dry electrodes, prototype pants that adopted a fit relative to a light clothing pressure (i.e. thigh: 1.3–1.9 kPa), and combined both silicon and silver thread embroidery with a wide contact area for stability, were designed and their sEMG measurements were confirmed.Originality/valueIn this study, wearable clothing based on textile electrodes was developed to ensure a comfortable fit from the wearer's perspective, and a design method was proposed for the development of low-cost SmartWear electrodes and circuits.

Muscle preactivation and the limits of muscle power output during jumping in the Cuban tree frog Osteopilus septentrionalis.

Previous studies of jumping in frogs have found power outputs in excess of what is possible from direct application of muscle power and concluded that jumping requires the storage and release of elastic strain energy. Of course, the muscles must produce the work required and their power output should be consistent with known muscle properties if the total duration of muscle activity is known. Using the Cuban tree frog, Osteopilus septentrionalis, I measured jumping performance from kinematics and used EMG measurements of three major jumping muscles to determine the duration of muscle activity. Using the total mass of all the hindlimb muscles, muscle mass-specific work output up to 60 J kg-1 was recorded. Distributed over the duration of the jump, both average and peak muscle mass-specific power output increased approximately linearly with the work done, reaching values of over 750 and 2000 W kg-1, respectively. However, the muscles were activated before the jump started. Both preactivation duration and EMG amplitude increased with increasing amounts of work performed. Assuming the muscles could produce work from EMG onset until toe-off, the average muscle mass-specific power over this longer interval also increased with work done, but only up to a work output of 36 J kg-1. The mean power above this value of work was 281 W kg-1, which is approximately 65% of the estimated maximum isotonic power. Several reasons are put forward for suggesting this power output, although within the known properties of the muscles, is nevertheless an impressive achievement.

Biomechanical analysis of lifting on stable versus unstable surfaces—a laboratory-based proof-of-concept study

BackgroundMany workers performing manual handling tasks suffer from musculoskeletal disorders (MSD). Previous research has identified several loading aspects associated with manual handling, but it is still unknown if lifting on an unstable surface is associated with increased biomechanical loading of different body parts.AimThis proof-of-concept study aims to study what kinematic and kinetic movement parameters, such as movement time, joint angles, torque, and muscle activity are feasible and of importance when studying the effect of lifting on surfaces with varying degrees of stability in an experimental set-up.MethodsMeasurements were taken during three different surface conditions: stable, slightly unstable, and unstable. The participants were instructed to lift a box from the floor and place it on a table in front of them. The weight of the box varied from 0.5 to 15.5 kg. By using a motion capture system (VICON) with 28 reflective markers placed on the participants and one on the box, one Kistler force plate for measuring force levels and center of pressure movements (CoP), and four electromyographic transmitters (EMG), we analyzed the downward and upward phases of the lifting movement, using the Friedman’s test for repeated measures.ResultsStatistically significant results with less joint movements in the lower and upper back were seen with increased instability during both the downward and upward phases. The decrease in trunk movements with increased instability resulted in a somewhat more flexed knee position during the movement, a lower torque in the lower back, and a decrease in CoP movements, but no differences in movement time or muscle activity in back and knee muscles.ConclusionLifting while standing on unstable surfaces resulted in an alteration of both kinematics and kinetics parameters; however, further studies regarding whether this is an additional risk factor for developing lower back pain are needed. Muscle activity levels were not altered due to instability and due to the complexity of the measurement, and we suggest not including EMG measures in future experiments of this type.

Effects Of A 4-week Neuromuscular Electrical Stimulation Treatment On Skeletal Muscle Endurance In Older Adults

Neuromuscular electrical stimulation (NMES) is often used as a rehabilitative modality and evidence has suggested that high frequency NMES (HF-NMES) may elicit increases in muscle strength. However, little is known regarding the effects of HF-NMES treatment on voluntary skeletal muscle endurance. PURPOSE: The aim of this study was to determine the effect of a 4-week HF-NMES intervention on muscular endurance and changes in neuromuscular activation patterns of the quadriceps during voluntary fatiguing muscle contractions in older adults. METHODS: Seventeen healthy older adults (68.8 ± 1.8 yrs; NMES: n = 12; SHAM: n = 5) completed the study. The NMES group underwent NMES treatment to the quadriceps of each leg 3x/week for 4 weeks at a 60 Hz stimulation frequency. Electrodes were applied to the SHAM group, but no current was delivered. All subjects performed maximal voluntary contractions (MVC) and a knee extension isometric submaximal voluntary fatigue task at 50% MVC until fatigue criteria were met. Surface electromyography (sEMG) of the vastus lateralis (VL) and vastus medialis (VM) muscles were recorded during the fatigue task and quantified for root mean square (RMS) EMG (percent rate of change during the fatigue task) and median frequency (MF) to examine changes in muscle activation. Repeated measures ANOVAs were used to determine differences pre-post NMES for muscular endurance time, MVC, and EMG measures. Statistical significance was set at p < 0.05. RESULTS: MVC increased in the NMES group (117.1 ± 8.7 Nm vs. 127.6 ± 11.1 Nm, p = 0.049; pre- and post-training, respectively) with no changes in SHAM (p = 0.96). No differences were observed pre-post training, respectively for muscular endurance time (NMES: 159.3 ± 20.1 s vs 141.9 ± 21.2 s, p = 0.29; SHAM: 242.2 ± 43.3 s vs 202.9 ± 23.3 s, p = 0.13), RMS EMG rate of change (NMES: VL: 16.6 ± 3.6% vs 18.8 ± 10.4%, p = 0.84; VM: 11.4 ± 2.1% vs 19.6 ± 5.5%, p = 0.15; SHAM: VL: 7.8 ± 1.6% vs 7.1 ± 3.0%, p = 0.81; VM: 7.1 ± 3.3% vs 5.9 ± 2.2%, p = 0.55) and MF EMG (NMES: VL: 77.6 ± 4.1 Hz vs 74.9 ± 3.6 Hz, p = 0.13; VM: 72.5 ± 2.4 Hz vs 72.6 ± 2.2 Hz, p = 0.97; SHAM: VL: 79.3 ± 3.4 Hz vs 80.2 ± 4.9 Hz, p = 0.85; VM: 76.9 ± 3.7 Hz vs 83.9 ± 5.1 Hz, p = 0.12). CONCLUSION: Treatment with HF-NMES did not improve muscle endurance or EMG-related parameters. HF-NMES may not be efficacious when the goal is to improve skeletal muscle endurance.

Synchronization of wearable motion capture and EMG measurement systems.

Synchronization of motion capture systems with other modalities in out-of-the-lab settings is not trivial. Various synchronization methods exist, such as using servers or transistor-transistor-logic pulses. However, not all measurement set-ups allow for such synchronization methods. Therefore, we have developed and validated an acceleration based post-measurement method to synchronize an IMU based motion capture system and an EMG measurement device. On top of the thigh IMU an additional accelerometer was placed which was connected to the analog input of the EMG device. By applying cross-correlation continuously, the similarities in the measured acceleration by the two measurement systems can be used for synchronization. We performed a validation measurement on seven able-bodied subjects and tested various correlation window sizes in hour long measurements in an out of the lab setting. It can be concluded that the developed method works for different activities when a suitable window length is chosen for cross-correlation. If no other options are available for synchronization, this correlation based method using an additional accelerometer is a viable option.

Application of EEG Signals Integration to Proprietary Classification Algorithms in the Implementation of Mobile Robot Control with the Use of Motor Imagery Supported by EMG Measurements

This article is a continuation and extension of research on a new approach to the classification and recognition of EEG signals. Their goal is to control the mobile robot through mental commands, using a measuring set such as Emotiv Epoc Flex Gel. The headset, despite its relative advancement, is rarely found in this type of research, which makes it possible to search for its advanced and innovative applications. The uniqueness of the proposed approach is the use of an EMG measuring device located on the biceps, i.e., MyoWare Muscle Sensor. This is to verify pure mental commands without additional muscle contractions. The participants of the study were asked to imagine the forearm movement that was responsible for triggering the movement command of the LEGO Mindstorms EV3 robot. The change in direction of movement is controlled by artifacts in the signal caused by the blink of an eyelid. The measured EEG signal was subjected to meticulous analysis by an expert system containing a classic classification algorithm and an artificial neural network. It was supposed to recognize mental commands, as well as detect artifacts in the form of blinking and change the direction of the robot’s movement. In addition, the system monitored the analysis of the EMG signal, detecting possible muscle tensions. The output of the expert algorithm was a control signal sent to the mobile robot.

TFC2: SCR, ECG, respiration, startle eyeblink EMG and eyetracking measurements in a trace fear conditioning task with acquisition and recall test after one week

TFC2: SCR, ECG, respiration, startle eyeblink EMG and eyetracking measurements in a trace fear conditioning task with acquisition and recall test after one week

TFC1: SCR, ECG, respiration, startle eyeblink EMG and eyetracking measurements in a trace fear conditioning task with acquisition and recall test after one week

TFC1: SCR, ECG, respiration, startle eyeblink EMG and eyetracking measurements in a trace fear conditioning task with acquisition and recall test after one week

DoxAv1: SCR, ECG, respiration, startle eyeblink EMG and eyetracking measurements in an RCT using doxycycline/placebo during trace fear conditioning and retention.

DoxAv1: SCR, ECG, respiration, startle eyeblink EMG and eyetracking measurements in an RCT using doxycycline/placebo during trace fear conditioning and retention.

A hybrid approach to product prototype usability testing based on surface EMG images and convolutional neural network classification

ObjectiveIt is common for employees to complain of muscle fatigue when resting in a reclined position in an office chair. To investigate the physical factors that influence resting comfort in a supine position, a newly designed product was used as the basis for creating a prototype experiment and testing its efficacy in use. Subjective questionnaires were combined with surface EMG measurements and deep learning algorithms were used to identify body part comfort to create a hybrid approach to product usability testing. MethodsTo facilitate the use of sEMG-based CNNs in human factors engineering, a subjective user assessment was first conducted using a combination of body mapping and an impact comfort scale to the screen which body parts have a significant impact effect on comfort when using the prototype. A control group (no used) and an experimental group (used) were then created and the body parts with the most significant effects were measured using sEMG methods. After pre-processing the sEMG signal, sMEG feature maps were obtained by mean power frequency (MPF) and linear regression was used to analyze the comforting effect. Finally, a CNN model is constructed and the sMEG feature maps are trained and tested. ResultsThe results of the experiment showed that the user's subjective assessment showed that 10 body parts had a significant effect on comfort, with the right and left sides of the neck having the highest effect on comfort (4.78). sEMG measurements were then performed on the sternocleidomastoid (SCM) of the left and right neck. Linear analysis of the measurements showed that the control group had higher SCM fatigue than the experimental group, which could also indicate that the experimental group had better comfort. The final CNN model was able to accurately classify the four datasets with an accuracy of 0.99. ConclusionThe results of the study show that the method is effective for the study of physical comfort in the supine sitting position and that it can be used to validate the comfort of similar products and to design iterations of the prototype.

Chemogenetic Activation of Hypoglossal Motoneurons in Neuromuscular Disease

The tongue is essential for breathing, swallowing, mastication, speech, coughing, and suckling. Many conditions and neuromuscular diseases are associated with lingual dysfunction, making it a priority to develop treatments which can improve tongue motor function. Our laboratory established that intralingual delivery of adeno‐associated virus serotype 9 (AAV9) encoding a particular gene can drive expression of that gene in hypoglossal motoneurons (XII MNs). This method can also drive expression of designer receptors exclusively activated by designer drugs (DREADDs) in XII MNs (Fleury‐Curado et al, 2021). Here we tested if intralingual delivery of AAV9‐hSyn‐hM3(Gq)‐mCherry could drive functional DREADD expression in XII MNs in a mouse model exhibiting tongue neuromuscular pathology. Specifically, we studied a mouse model of Pompe disease (Gaa‐/‐). The prevalence of Pompe disease is estimated to be 1 per 8,700 live births and is associated with macroglossia, dysphagia, dysarthria, sleep disordered breathing, and XII MN pathology. Intralingual injections of AAV9‐hSyn‐hM3(Gq)‐mCherry (2.4 x 1011 vg) or saline (sham) were administered to the base of tongue in anesthetized Pompe mice (AAV9‐DREADD n=11, saline n=4) or wild type (C57BL//6J mice (AAV9‐DREADD, n=5) at 4‐6 weeks of age. Lingual EMG activity was measured during spontaneous breathing under isoflurane anesthesia 12 weeks later. Tonic and phasic inspiratory EMG responses to intraperitoneal injection of saline (i.e., vehicle) or the DREADD ligand JHU37160‐dihydrochloride (J60) were assessed. Saline produced no significant changes in lingual EMG measures. All Pompe mice studied responded to J60 with an increase in tonic lingual EMG activity (time to response, TTR = 219±68 seconds; 1034±350% baseline at 30 min). Only 1 of 5 mice showed discernable increase in tonic EMG output after J60. The DREADD ligand produced an increase in phasic inspiratory bursting in all Pompe mice (TTR = 197±78 seconds; 506±248% baseline at 30 min). The increase in phasic bursting also occurred in all WT mice (TTR = 161±22 seconds; 512±151% baseline at 30 min). The DREADD ligand also caused a decrease in respiratory rate (bursts per minute) that was more pronounced in Pompe mice (79±5% baseline at 30 min post‐J60) compared to WT mice (91±12% baseline at 30 min post‐J60. Histological evaluation of the medulla confirmed expression of the mCherry fluorophore in XII MNs in all animals that received intralingual injection of AAV9‐hSyn‐hM3(Gq)‐mCherry. We conclude that intralingual delivery of an AAV9 vector encoding a DREADD can drive functional expression of DREADDs in XII MNs in a mouse model of Pompe disease that displays lingual myofiber atrophy and XII MN pathology. Thus, the ongoing neuromuscular pathology did not prevent the efficacy of chemogenetic tongue muscle activation. Indeed, the DREADD ligand caused a robust increase in both tonic and phasic lingual EMG activity in Pompe mice. The tonic EMG response appears to be more consistent in Pompe vs WT mice.

CTX2: SCR, ECG, respiration, and startle eyeblink EMG measurements in a contextual fear conditioning task under VR with acquisition and recall test after one week

CTX2: SCR, ECG, respiration, and startle eyeblink EMG measurements in a contextual fear conditioning task under VR with acquisition and recall test after one week

CTX3: SCR, ECG, respiration, and startle eyeblink EMG measurements in a contextual fear conditioning task under VR with acquisition and recall test after one week

CTX3: SCR, ECG, respiration, and startle eyeblink EMG measurements in a contextual fear conditioning task under VR with acquisition and recall test after one week