1,721,110 research outputs found
Tutorial. Surface EMG detection, conditioning and pre-processing: Best practices
Full text linkThis tutorial is aimed primarily to non-engineers, using or planning to use surface electromyography (sEMG) as
an assessment tool for muscle evaluation in the prevention, monitoring, assessment and rehabilitation fields. The
main purpose is to explain basic concepts related to: (a) signal detection (electrodes, electrode–skin interface,
noise, ECG and power line interference), (b) basic signal properties, such as amplitude and bandwidth, (c)
parameters of the front-end amplifier (input impedance, noise, CMRR, bandwidth, etc.), (d) techniques for interference
and artifact reduction, (e) signal filtering, (f) sampling and (g) A/D conversion, These concepts are
addressed and discussed, with examples.
The second purpose is to outline best practices and provide general guidelines for proper signal detection,
conditioning and A/D conversion, aimed to clinical operators and biomedical engineers. Issues related to the
sEMG origin and to electrode size, interelectrode distance and location, have been discussed in a previous tutorial.
Issues related to signal processing for information extraction will be discussed in a subsequent tutorial
Editorial: Surface EMG and other measurement techniques in rehabilitation research and practice: are new educational programs needed?
Full text linkNon disponibil
Identification of periodic bursts in surface EMG: Applications to the erector spinae muscles of sitting violin players
Full text linkObjective: This work compares two known and one novel techniques for the detection of surface EMG (sEMG) quasi-periodic burst-like signals and the estimation of their frequency. The novel method (ES) is based on the spectral analysis of the envelope signal, the other two methods use a fixed (FT) or automatically selected optimal threshold (OT). Methods: The methods are compared using both simulated signals and samples of High Density sEMG experimental signals collected using electrode arrays applied to the erector spinae muscles of violinists. Results: The ES method does not require thresholds. It detects presence/absence of bursts and their frequency, even in cases of a few missing bursts. It does not provide their duration. The FT method requires the selection of a fixed threshold value, estimates burst duration but is applicable only if bursts are present. The OT method identifies an optimal threshold, estimates burst duration but behaves irregularly when bursts are small or absent. Conclusions: The ES method provides the estimates closest to those of an expert human counter and is not sensitive to amplitude fluctuations. It is suitable when the general bursts periodicity is of interest even if some bursts may be missing. The FT and OT methods are sensitive to amplitude fluctuations and identify random threshold crossings as bursts even when burst activity is absent. Significance: Postural muscles are often activated in a burst-like fashion. The proposed ES method identifies presence/absence of bursts and their frequency, which is important for studying the neurophysiological mechanism generating them
Valutazione quantitativa di fenomeni e proprietà muscolari tramite segnale mioelettrico cutaneo 1. Metodologie, strumenti hardware e software
No full text
Comparison of chairs based on HDsEMG of back muscles, biomechanical and comfort indices, for violin and viola players: A short-term study
No full textThis work investigates the effect of different seats on violin and viola players sitting postures using High-Density-surface-Electromyography techniques (HDsEMG), biomechanical and comfort indices. Five types of chairs were assessed on 18 violin and three viola players by comparing: (a) pelvic tilt and kyphosis and lordosis angles, (b) subjective comfort indices, and (c) EMG amplitude of erector spinae and trapezius. Sitting “as you like” on a standard orchestra chair is the condition with the highest subjective comfort (but not significantly different from other chairs). A saddle chair with low back support is associated to the lowest EMG of the erector spinae (p < 0.05) and a saddle stool is associated to the spinal angles closest to those of the standing posture. In 12 out of 21 (57%) musicians, the erector spinae was activated in an intermittent manner, regardless of the chair used. These findings justify further research on the selected chairs, on muscle fatigue and on the intermittent postural control strategy
Investigation of motor unit recruitment during stimulated contractions of tibialis anterior muscle.
No full textThis work investigated motor unit (MU) recruitment during transcutaneous electrical stimulation (TES) of the tibialis anterior (TA) muscle, using experimental and simulated data. Surface electromyogram (EMG) and torque were measured during electrically-elicited contractions at different current intensities, on eight healthy subjects. EMG detected during stimulation (M-wave) was simulated selecting the elicited MUs on the basis of: (a) the simulated current density distribution in the territory of each MU and (b) the excitation threshold characteristic of the MU. Exerted force was simulated by adding the contribution of each of the elicited MUs. The effects of different fat layer thickness (between 2 and 8mm), different distributions of excitation thresholds (random excitation threshold, higher threshold for larger MUs or smaller MUs), and different MU distributions within the muscle (random distribution, larger MU deeper in the muscle, smaller MU deeper) on EMG variables and torque were tested. Increase of the current intensity led to a first rapid increase of experimental M-wave amplitude, followed by a plateau. Further increases of the stimulation current determined an increase of the exerted force, without relevant changes of the M-wave. Similar results were obtained in simulations. Rate of change of conduction velocity (CV) and leading coefficient of the second order polynomial interpolating the force vs. stimulation level curve were estimated as a function of increasing current amplitudes. Experimental data showed an increase of estimated CV with increasing levels of the stimulation current (for all subjects) and a positive leading coefficient of force vs. stimulation current curve (for five of eight subjects). Simulations matched the experimental results only when larger MUs were preferably located deeper in the TA muscle (in line with a histochemical study). Marginal effect of MU excitation thresholds was observed, suggesting that MUs closer to the stimulation electrode are recruited first during TES regardless of their excitability
Effect of accelerometer location on mechanomyogram variables during voluntary, constant-force contractions in three human muscles
No full textCharacterization of surface electromyograms by means of recurrence quantification analysis: a comparison with frequency domain analysis
No full textMONTREAL (CANADA
- …
