Avtor/Urednik		McKay, WB; Stokić, DS; Sherwood, AM; Vrbova, G; Dimitrijević, MR
Naslov		Effect of fatiguing maximal voluntary contraction on excitatory and inhibitory responses elicited by transcranial magnetic motor cortex stimulation
Tip		članek
Vir		Muscle Nerve
Vol. in št.		Letnik 19, št. 8
Leto izdaje		1996
Obseg		str. 1017-24
Jezik		eng
Abstrakt		Vertex transcranial magnetic stimulation (TMS) elicited tibialis anterior motor evoked potentials (MEPs) and silent periods (SPs) that were recorded during and following isometric maximal volitional contraction (MVC). During MVC in 6 healthy subjects, MEP amplitudes in the exercised muscle showed an increasing trend from an initial value of 4539 +/- 809 muV (mean +/- SE) to 550 +/- 908 muV (P < 0.13) while force and EMG decreased (P < 0.01). Also, SP duration increased from 165 +/- 37 ms to 231 +/- 32 ms (P < 0.01). Thus, during a fatiguing MVC both excitatory and inhibitory TMS-induced responses increased. TMS delivered during repeated brief 10% MVC contractions before and after a fatiguing MVC in 5 subjects, showed no change in MEP amplitude but SP duration was prolonged after MVC. This SP prolongation was focal to the exercised muscle. Silent periods recorded after pyramidal tract stimulation were unchanged following the MVC. These results suggest that MEP and SP might have common sources of facilitation during an MVC and that inhibitory mechanisms remain focally augmented following a fatiguing MVC.
Deskriptorji		MOTOR CORTEX MUSCLE CONTRACTION FATIGUE ADULT MIDDLE AGE ELECTRIC STIMULATION ELECTROMYOGRAPHY EVOKED POTENTIALS