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Alterations in corticospinal excitability with imposed vs. voluntary fatigue in human hand muscles
journal contribution
posted on 2002-05-01, 00:00 authored by Julia Pitcher, Timothy S MilesWe aimed to determine whether postexercise depression of motor-evoked potentials (MEPs) could be demonstrated without voluntary muscle activation in humans. Voluntary fatigue was induced with a 2-min maximal voluntary contraction (MVC) of the first dorsal interosseous (FDI) muscle. On another occasion, “electrical fatigue” was induced with trains of shocks delivered for 2 min over the FDI motor point. Five of the twelve subjects also underwent “sequential fatigue” consisting of a 2-min MVC of FDI followed by 20 min of rest and then 2 min of motor point stimulation. Voluntary fatigue induced MEP depression that persisted for at least 20 min. Electrical fatigue induced a transient MEP facilitation that subsided 20 min after the stimulation and became depressed within 30 min. Thus MEP depression can be induced by both voluntary and electrical fatigue. With electrical fatigue, the initial depression is “masked” by transient MEP facilitation, reflecting cortical plasticity induced by the prolonged electrical stimulation. MEP depression probably reflects tonic afferent input from the exercising muscle that alters cortical excitability without altering spinal excitability.
History
Journal
Journal of Applied PhysiologyVolume
92Issue
5Pagination
2131 - 2138Publisher
American Physiological SocietyLocation
United StatesPublisher DOI
ISSN
8750-7587eISSN
1522-1601Language
enPublication classification
C1 Refereed article in a scholarly journalUsage metrics
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Science & TechnologyLife Sciences & BiomedicinePhysiologySport Sciencestranscranial magnetic stimulationmotor cortexafferentsplasticitymotor-evoked potentialMOTOR-EVOKED-POTENTIALSPERIPHERAL-NERVE STIMULATIONCORTICAL EXCITABILITYHUMAN MOTONEURONSDEPRESSIONREORGANIZATIONRESPONSESCORTEXINHIBITIONMODULATION
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