Article

Eight males and three females subjects performed four bouts of isometric elbow flexion. Each bout consisted of two trials at 25, 50 75 and 100 percent of the preestablished maximal voluntary isometric tension (MVIC), measured from the output of a piezoelectric force transducer. During the trials, surface EMG was sampled from the belly of the biceps brachii. Surface measures representing motor unit discharge frequency-zero crossings and spikes, were collected digitally using electronic discriminator values representing zero (zero crossings), 25, 50 and 75 percent of the magnitude of the peak raw EMG voltage during MVIC which was derived electronically prior to testing. Manually quantified data were obtained from an oscillograph tracing for the identical sampling period (500 msec). Statistical analysis levels, but neither manual nor digital data were consistant in discriminating tension levels. Analysis did indicate, however, that use of digital techniques and 50% discriminator allowed inferences regarding the dominant type of motor (tonic versus phasic) activated during isometric contraction which is consistent with contemporary recruitment theory. The importance of these findings lies in the information regarding neural control of muscular contraction unavailable with other quantification techniques.

Langue : ANGLAIS

Identifiant basis : 1986000075