An electromyographic volley at initiation of rapid isometric contractions of the elbow.
When normal subjects made rapid isometric extensions of the elbow to target torque, the agonist electromyograms (EMGs), recorded by a monopolar surface electrode, initiated from an EMG volley which was characterized by a negative potential immediately followed by a positive one. This study examined properties of the EMG volley and determined whether or not it is a movement artifact. Surface EMGs recorded by multiple monopolar electrodes showed that the negative peak of the EMG volley was earliest and greatest in amplitude at the motor point region. The integrated negative potential correlated with peak torque. EMGs recorded by needle and bipolar surface electrodes showed a duration of comparative activity with the EMG volley. To eliminate movements between the skin and monopolar electrode, the skin around the electrode was clamped to a fixture. This left the EMG volley unchanged. The antagonist showed a similar EMG volley, but was less stable in duration and amplitude. Our results demonstrated that the EMG volley is not a movement artifact.
Yamazaki
Y
Y
Department of Health and Physical Education, Nagoya Institute of Technology, Japan.
Suzuki
M
M
Mano
T
T
D000328:Adult; D004551:Elbow Joint / Q000502:physiology*; D004566:Electrodes; D004576:Electromyography / Q000295:instrumentation / Q000379:methods; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D009132:Muscles / Q000294:innervation / Q000502:physiology*; D013997:Time Factors