Single motor unit analysis from spatially filtered surface electromyogram signals. Part 2: Conduction velocity estimation

2003 ◽  
Vol 41 (3) ◽  
pp. 338-345 ◽  
Author(s):  
E. Schulte ◽  
D. Farina ◽  
G. Rau ◽  
R. Merletti ◽  
C. Disselhorst-Klug
Keyword(s):  
Motor Unit ◽  
Conduction Velocity ◽  
Velocity Estimation ◽  
Surface Electromyogram ◽  
Single Motor Unit ◽  
Single Motor ◽  
Unit Analysis

Conduction velocity of low-threshold motor units during ischemic contractions performed with surface EMG feedback

2005 ◽  
Vol 98 (4) ◽  
pp. 1487-1494 ◽  
Author(s):  
Dario Farina ◽  
Marco Gazzoni ◽  
Federico Camelia
Keyword(s):  
Motor Unit ◽  
Conduction Velocity ◽  
Action Potential Duration ◽  
Surface Emg ◽  
Mean Power ◽  
Single Motor Unit ◽  
Single Motor ◽  
Power Spectral ◽  
Low Threshold ◽  
Spectral Frequency

The aim of this study was to analyze the effect of ischemia on low-threshold motor unit conduction velocity. Nine subjects were trained to isolate the activity of a single motor unit (target motor unit) in the abductor pollicis brevis muscle with feedback on surface EMG signals recorded with a 16-electrode linear array. After training, the subjects activated the target motor unit at ∼8 pulses per second (pps) for five 3-min-long contractions. During the third and fourth contractions, a cuff inflated at 180 mmHg around the forearm induced ischemia of the hand. The exerted force (mean ± SE, 4.6 ± 2.1% of the maximal voluntary contraction force), discharge rate (8.6 ± 0.4 pps), interpulse interval variability (34.8 ± 2.5%), and peak-to-peak amplitude of the target motor unit action potentials (176.6 ± 18.2 μV) were not different among the five contractions. Conduction velocity, mean power spectral frequency, and action potential duration were the same in the beginning of the five contractions (2.8 ± 0.2 m/s, 195.2 ± 10.5 Hz, and 5.4 ± 0.3 ms, respectively) and changed over the 3 min of sustained activation only during the fourth contraction. Conduction velocity and mean power spectral frequency decreased (10.05 ± 1.8% and 8.50 ± 2.18% during the 3 min, respectively) and action potential duration increased (8.2 ± 4.6% in the 3 min) during the fourth contraction. In conclusion, 1) subjects were able to isolate the activity of a single motor unit with surface EMG visual feedback in ischemic conditions maintained for 16 min, and 2) the activation-induced decrease in single motor unit conduction velocity was significantly larger with ischemia than with normal circulation, probably due to the alteration of mechanisms of ion exchange across the fiber membrane.

Optimal placement of bipolar surface EMG electrodes in the face based on single motor unit analysis

2010 ◽  
Vol 47 (2) ◽  
pp. 299-314 ◽  
Author(s):  
Bernd G. Lapatki ◽  
Robert Oostenveld ◽  
Johannes P. Van Dijk ◽  
Irmtrud E. Jonas ◽  
Machiel J. Zwarts ◽  
...  
Keyword(s):  
Motor Unit ◽  
Surface Emg ◽  
Optimal Placement ◽  
Single Motor Unit ◽  
Single Motor ◽  
The Face ◽  
Emg Electrodes ◽  
Unit Analysis
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