ISSN:
1439-6327
Keywords:
Integrated electromyographic activity
;
Electromyographic DC potential
;
Muscularforce
;
Fatigue
;
Electromyographic slow wave
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The present experiment was undertaken to demonstrate the effect of muscular force as well as duration of muscular work on the electromyographic (EMG) DC potential. Thirty subjects had to lift different weights by flexing the right forearm within a defined and constant setting for 20 s. The experimental variables were weight (0.5, 1, 2, and 3 kg) and time. The EMG was recorded from the belly of the right biceps brachii muscle in a quasi-unipolar manner and split into an integrated ac channel (IEMG) and a dc channel (DC-EMG). The average IEMG showed a ramp-like shape. Analysis showed a positive relationship for weight (p〈0.0001) and time (p〈0.0001) with the IEMG. The average shape of the DC-EMG showed a negative initiation potential, a monotonically increasing negative potential during contraction (contraction potential), a positively peaking off potential and a slow return to baseline (after potential). Analyses of variance demonstrated a significant (p〈0.001) relationship of weight to the magnitude of the initiation and the termination potential. Regression analyses displayed an inverse relationship of time to the termination (p〈0.01) and to the resolution potential (p〈0.001). The DC-EMG showed higher peaks (initiation and termination potential) for heavier weights. For the termination and after potential less positive deflections were found with increasing time (fatigue). A control condition (isometric contraction) indicated that the initiation, contraction, and termination potential of the DC-EMG may also be related to aspects of the movement. Results suggest that the DC-EMG is a more complex measure of muscular activity than the IEMG.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02330697
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