Does vibration superimposed on low-level isometric contraction alter motor unit recruitment strategy?

Xu, Lin; Negro, Francesco; Xu, Yu; Rabotti, C.; Schep, Goof; Farina, Dario; Mischi, Massimo

doi:10.1088/1741-2552/aadc43

Cited by 15 publications

(11 citation statements)

References 47 publications

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“…The subject was instructed to pull against the rope in order to perform isometric arm exercise with the back straight and the elbow angle equal to 90 degrees. The applied force was 50% of his/her maximum voluntary contraction (MVC), which was measured prior to the exercise by a load-cell embedded in the experimental setup following the protocol described in [ 25 ]. The entire experiment took 60 s, including two 15 s isometric contractions and three 10 s rest periods, as shown in Figure 1 a.…”

Section: Methodsmentioning

confidence: 99%

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Comparative Review of the Algorithms for Removal of Electrocardiographic Interference from Trunk Electromyography

Peri

Vullings

et al. 2020

Sensors

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Surface electromyogram (EMG) is a noninvasive measure of muscle electrical activity and has been widely used in a variety of applications. When recorded from the trunk, surface EMG can be contaminated by the cardiac electrical activity, i.e., the electrocardiogram (ECG). ECG may distort the desired EMG signal, complicating the extraction of reliable information from the trunk EMG. Several methods are available for ECG removal from the trunk EMG, but a comparative assessment of the performance of these methods is lacking, limiting the possibility of selecting a suitable method for specific applications. The aim of the present study is therefore to review and compare the performance of different ECG removal methods from the trunk EMG. To this end, a synthetic dataset was generated by combining in vivo EMG signals recorded on the biceps brachii and healthy or dysrhythmia ECG data from the Physionet database with a predefined signal-to-noise ratio. Gating, high-pass filtering, template subtraction, wavelet transform, adaptive filtering, and blind source separation were implemented for ECG removal. A robust measure of Kurtosis, i.e., KR2 and two EMG features, the average rectified value (ARV), and mean frequency (MF), were then calculated from the processed EMG signals and compared with the EMG before mixing. Our results indicate template subtraction to produce the lowest root mean square error in both ARV and MF, providing useful insight for the selection of a suitable ECG removal method.

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Section: Methodsmentioning

confidence: 99%

“…For each channel,

was calculated on the entire 60 s reconstructed EMG signal. ARV was calculated in a 1 s sliding window with no overlap, in line with [ 25 ]. MF was calculated using the same sliding window, but only during the two contraction periods as shown in Figure 1 a.…”

Section: Methodsmentioning

confidence: 99%

Comparative Review of the Algorithms for Removal of Electrocardiographic Interference from Trunk Electromyography

Peri

Vullings

et al. 2020

Sensors

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“…However, it is still unclear whether the spectral peaks correlating with the stimulation frequencies are in fact motion artefacts [31] or stretch reflexes [13]. Recent evidence suggests that these peaks might indeed be stretch reflexes [33,34]. Considering the present ambiguity about the existence of motion artefacts and increasing evidence of the presence of stretch reflex [13,33,34], only the spectra exhibiting the largest power and hence potential to skew the results were removed.…”

Section: Methodsmentioning

confidence: 99%

“…Recent evidence suggests that these peaks might indeed be stretch reflexes [33,34]. Considering the present ambiguity about the existence of motion artefacts and increasing evidence of the presence of stretch reflex [13,33,34], only the spectra exhibiting the largest power and hence potential to skew the results were removed. The largest spectra were found to be at 50 Hz coinciding with mains frequency of some of the equipment.…”

Section: Methodsmentioning

confidence: 99%

Fatiguing effects of indirect vibration stimulation in upper limb muscles: pre, post and during isometric contractions superimposed on upper limb vibration

2019

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Whole-body vibration and upper limb vibration (ULV) continue to gain popularity as exercise intervention for rehabilitation and sports applications. However, the fatiguing effects of indirect vibration stimulation are not yet fully understood. We investigated the effects of ULV stimulation superimposed on fatiguing isometric contractions using a purpose developed upper limb stimulation device. Thirteen healthy volunteers were exposed to both ULV superimposed to fatiguing isometric contractions (V) and isometric contractions alone Control (C). Both Vibration (V) and Control (C) exercises were performed at 80% of the maximum voluntary contractions. The stimulation used was 30 Hz frequency of 0.4 mm amplitude. Surface-electromyographic (EMG) activity of the Biceps Brachii, Triceps Brachii and Flexor Carpi Radialis were measured. EMG amplitude (EMGrms) and mean frequency (MEF) were computed to quantify muscle activity and fatigue levels. All muscles displayed significantly higher reduction in MEFs and a corresponding significant increase in EMGrms with the V than the Control, during fatiguing contractions (p < 0.05). Post vibration, all muscles showed higher levels of MEFs after recovery compared to the control. Our results show that near-maximal isometric fatiguing contractions superimposed on vibration stimulation lead to a higher rate of fatigue development compared to the isometric contraction alone in the upper limb muscles. Results also show higher manifestation of mechanical fatigue post treatment with vibration compared to the control. Vibration superimposed on isometric contraction not only seems to alter the neuromuscular function during fatiguing efforts by inducing higher neuromuscular load but also post vibration treatment.

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“…The experimental setup is shown in Figure 1. Further details on the acquisition protocol were described in detail in previous works from our group [34,35]. The protocol was approved by the Ethical Committee of the Máxima Medical Center (Veldhoven, the Netherlands).…”

Section: Synthetic Trunk Emgmentioning

confidence: 99%

Singular Value Decomposition for Removal of Cardiac Interference from Trunk Electromyogram

Peri

Ciccarelli

et al. 2021

Sensors

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A new algorithm based on singular value decomposition (SVD) to remove cardiac contamination from trunk electromyography (EMG) is proposed. Its performance is compared to currently available algorithms at different signal-to-noise ratios (SNRs). The algorithm is applied on individual channels. An experimental calibration curve to adjust the number of SVD components to the SNR (0–20 dB) is proposed. A synthetic dataset is generated by the combination of electrocardiography (ECG) and EMG to establish a ground truth reference for validation. The performance is compared with state-of-the-art algorithms: gating, high-pass filtering, template subtraction (TS), and independent component analysis (ICA). Its applicability on real data is investigated in an illustrative diaphragm EMG of a patient with sleep apnea. The SVD-based algorithm outperforms existing methods in reconstructing trunk EMG. It is superior to the others in the time (relative mean squared error < 15%) and frequency (shift in mean frequency < 1 Hz) domains. Its feasibility is proven on diaphragm EMG, which shows a better agreement with the respiratory cycle (correlation coefficient = 0.81, p-value < 0.01) compared with TS and ICA. Its application on real data is promising to non-obtrusively estimate respiratory effort for sleep-related breathing disorders. The algorithm is not limited to the need for additional reference ECG, increasing its applicability in clinical practice.

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Does vibration superimposed on low-level isometric contraction alter motor unit recruitment strategy?

Abstract: These results suggest that vibration superimposed on low-level isometric contraction alters the MU recruitment strategy, activating larger and faster MUs.

Cited by 15 publications

References 47 publications

Comparative Review of the Algorithms for Removal of Electrocardiographic Interference from Trunk Electromyography

Comparative Review of the Algorithms for Removal of Electrocardiographic Interference from Trunk Electromyography

Fatiguing effects of indirect vibration stimulation in upper limb muscles: pre, post and during isometric contractions superimposed on upper limb vibration

Singular Value Decomposition for Removal of Cardiac Interference from Trunk Electromyogram

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