Influence of motoneuron firing synchronization on SEMG characteristics in dependence of electrode position

Kleine, Bert U.; Stegeman, Dick F.; Mund, Daniela; Anders, Christoph

doi:10.1152/jappl.2001.91.4.1588

Cited by 94 publications

(94 citation statements)

References 39 publications

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“…Weytjens and van Steenberghe (44) extended the derivations of Lago and Jones (27) on the effect of MU firing statistics on the surface EMG power spectrum to the case of dependent firings and showed that cross-terms arise that increase the energy of the signal mostly at low frequencies. Hermens et al (22) validated this analytic observation by a simulation model, and similar results were shown, more recently, by Yao et al (45) and, with the inclusion of the electrode location variability, by Kleine et al (25). Our results are in line with these previous studies and confirm the role of synchronization in determining MNF and MDF patterns during fatigue.…”

Section: Effect Of Mu Synchronization Level On Linear and Nonlinear Esupporting

confidence: 91%

“…The noise was then divided into a common and an individual part to simulate different degrees of synchronization. However, when comparing the synchronization level introduced by their method with that introduced by Yao et al (45), these authors concluded that similar results were obtained (25); thus the choice of one of the two models is probably not critical in the context of this study.…”

Section: Simulation Of the Mu Firing Patternssupporting

confidence: 67%

“…MDF led to results similar to those for MNF. Assuming, for example, decreasing mean CV (31) and increasing synchronization (25) Figure 5 shows the scatterplot between %Det and MNF normalized with respect to the mean values computed over all of the simulation set (n ϭ 1,500). A high correlation was found between the two variables in the simulated conditions (linear regression analysis, R ϭ Ϫ0.95, P Ͻ 0.001).…”

Section: Experimental Protocolmentioning

confidence: 99%

“…To explain these results, changes in MU CV distribution spread, increase of the depolarization zone length, or increase in MU short-term synchronization has been suggested (31), although with no direct evidence. Among these factors, recent results indicated a major role of MU synchronization (25,45). However, the ability of surface EMG spectral analysis as an indicator of MU short-term synchronization is still under debate.…”

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confidence: 99%

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Nonlinear surface EMG analysis to detect changes of motor unit conduction velocity and synchronization

Farina

Fattorini

Felici

et al. 2002

Journal of Applied Physiology

170

142

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. Nonlinear surface EMG analysis to detect changes of motor unit conduction velocity and synchronization. J Appl Physiol 93: 1753-1763. First published August 9, 2002 10.1152/japplphysiol.00314.2002Amplitude and frequency content of the surface electromyographic (EMG) signal reflect central and peripheral modifications of the neuromuscular system. Classic surface EMG spectral variables applied to assess muscle functions are the centroid and median power spectral frequencies. More recently, nonlinear tools have been introduced to analyze the surface EMG; among them, the recurrence quantification analysis (RQA) was shown to be particularly promising for the detection of muscle status changes. The purpose of this work was to analyze the effect of motor unit short-term synchronization and conduction velocity (CV) on EMG spectral variables and two variables extracted by RQA, the percentage of recurrence (%Rec) and determinism (%Det). The study was performed on the basis of a simulation model, which allowed changing the degree of synchronization and mean CV of a number of motor units, and of an experimental investigation of the surface EMG signal properties detected during high-force-level isometric fatiguing contractions of the biceps brachii muscle. Simulations and experimental results were largely in agreement and show that 1) spectral variables, %Rec, and %Det are influenced by CV and degree of synchronization; 2) spectral variables are highly correlated with %Det (R ϭ Ϫ0.95 in the simulations and Ϫ0.78 and Ϫ0.75 for the initial values and normalized slopes, respectively, in the experimental signals), and thus the information they provide on muscle properties is basically the same; and 3) variations of %Det and %Rec in response to changes in muscle properties are significantly larger than the variations of spectral variables. This study validates RQA as a means for fatigue assessment with potential advantages (such as the higher sensitivity to changes of muscle status) with respect to the classic spectral analysis. surface electromyography; motor unit short-term synchronization; surface electromyographic modeling; recurrence plot analysis THE SURFACE ELECTROMYOGRAPHIC (EMG) signal presents smaller bandwidth with respect to the intramuscular EMG, because the tissues separating the muscle fibers and the recording electrodes act as low-pass filters (15,28). This determines low-spatial selectivity, which hinders the separation of the contributions of different motor units (MUs). For this reason, past research efforts in the surface EMG field were mainly devoted to the development of processing techniques in time and frequency domain, which gave indications about the global EMG activity, without aiming at an analysis at the single MU level. Although, recently, techniques for noninvasive assessment of single MU properties have been proposed and refined (4,6,8), their applicability is still limited by the need of complex detection systems, to low-contraction levels, and controlled laboratory conditions for signal recordi...

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Section: Effect Of Mu Synchronization Level On Linear and Nonlinear Esupporting

confidence: 91%

Section: Simulation Of the Mu Firing Patternssupporting

confidence: 67%

Section: Experimental Protocolmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Nonlinear surface EMG analysis to detect changes of motor unit conduction velocity and synchronization

Farina

Fattorini

Felici

et al. 2002

Journal of Applied Physiology

170

142

View full text Add to dashboard Cite

show abstract

“…The recruitment follows the ''size principle' ' (Henneman et al, 1965), where bigger and faster motor units are recruited which may cause an increase in MDF (Gazzoni et al, 2001). The increased RMS amplitude may also be due to a Synchronization in motor unit firing, but this should also lead to a decrease in MDF (Kleine et al, 2001;, which was not observed in our data. …”

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confidence: 38%