Spectral properties of surface EMG and muscle conduction velocity: A study based on sEMG model

2011 ◽  
Author(s):  
Sridhar P Arjunan ◽  
Dinesh Kumar ◽  
Katherine Wheeler ◽  
Hirokazu Shimada ◽  
Ganesh Naik
Keyword(s):  
Conduction Velocity ◽  
Spectral Properties ◽  
Surface Emg

Amplitude cancellation reduces the size of motor unit potentials averaged from the surface EMG

2006 ◽  
Vol 100 (6) ◽  
pp. 1928-1937 ◽  
Author(s):  
Kevin G. Keenan ◽  
Dario Farina ◽  
Roberto Merletti ◽  
Roger M. Enoka
Keyword(s):  
Motor Unit ◽  
Conduction Velocity ◽  
Motor Units ◽  
Surface Emg ◽  
Excitation Level ◽  
Bipolar Electrode ◽  
Emg Signal ◽  
Motor Unit Synchronization ◽  
Rate Coding ◽  
Simulated Surface

The purpose of the study was to evaluate the influence of selected physiological parameters on amplitude cancellation in the simulated surface electromyogram (EMG) and the consequences for spike-triggered averages of motor unit potentials derived from the interference and rectified EMG signals. The surface EMG was simulated from prescribed recruitment and rate coding characteristics of a motor unit population. The potentials of the motor units were detected on the skin over a hand muscle with a bipolar electrode configuration. Averages derived from the EMG signal were generated using the discharge times for each of the 24 motor units with lowest recruitment thresholds from a population of 120 across three conditions: 1) excitation level; 2) motor unit conduction velocity; and 3) motor unit synchronization. The area of the surface-detected potential was compared with potentials averaged from the interference, rectified, and no-cancellation EMGs. The no-cancellation EMG comprised motor unit potentials that were rectified before they were summed, thereby preventing cancellation between the opposite phases of the potentials. The percent decrease in area of potentials extracted from the rectified EMG was linearly related to the amount of amplitude cancellation in the interference EMG signal, with the amount of cancellation influenced by variation in excitation level and motor unit conduction velocity. Motor unit synchronization increased potentials derived from both the rectified and interference EMG signals, although cancellation limited the increase in area for both potentials. These findings document the influence of amplitude cancellation on motor unit potentials averaged from the surface EMG and the consequences for using the procedure to characterize motor unit properties.

The boundary conditions for measurement of the conduction velocity of muscle fibres with surface EMG

1983 ◽  
Vol 56 (3) ◽  
pp. S49 ◽  
Author(s):  
Kasper Boon ◽  
Hermi Hermens ◽  
Charl Van't Esteinde ◽  
Gert Sollie ◽  
Willemin Wallinga-De Jonge
Keyword(s):  
Boundary Conditions ◽  
Conduction Velocity ◽  
Surface Emg ◽  
Muscle Fibres

Conduction velocity and EMG power spectrum changes in fatigue of sustained maximal efforts

1981 ◽  
Vol 51 (5) ◽  
pp. 1300-1305 ◽  
Author(s):  
B. Bigland-Ritchie ◽  
E. F. Donovan ◽  
C. S. Roussos
Keyword(s):  
Power Spectrum ◽  
Conduction Velocity ◽  
Surface Emg ◽  
Voluntary Contraction ◽  
Mass Action ◽  
Wave Form ◽  
Muscle Temperature ◽  
Voluntary Activity ◽  
Adductor Pollicis Muscle ◽  
Emg Power Spectrum

The relationship between the electromyographic (EMG) power spectrum and muscle conduction velocity was investigated during both fatiguing and nonfatiguing contractions of the adductor pollicis muscle. Changes in the EMG power spectrum were measured by Fourier transform analysis and by comparing the power in the high (130–238 Hz) and low (20--40 Hz) frequency bands. Changes in conduction velocity were measured during voluntary activity from changes in the muscle mass action potential evoked by periodic maximal shocks to the nerve. This was varied independently either by maintaining a 60-s fatiguing maximal voluntary contraction involving 30--50% loss of force or by changing muscle temperature in the absence of fatigue. Both procedures resulted in similar changes in the power spectrum. However, the change in conduction velocity required to generate equal changes in the EMG was about 10 times greater in the absence of fatigue than those observed during a 60-s maximum contraction initiated at any initial muscle temperature. This suggests that during fatigue of maximal voluntary contractions, factors other than changes in the wave form of individual muscle fiber action potentials must contribute to the observed shift in the total surface EMG frequency components.

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