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Type: Journal article
Title: Alterations in corticospinal excitability with imposed vs. voluntary fatigue in human hand muscles
Author: Pitcher, J.
Miles, T.
Citation: Journal of Applied Physiology, 2002; 92(5):2131-2138
Publisher: Amer Physiological Soc
Issue Date: 2002
ISSN: 8750-7587
Statement of
Julia B. Pitcher and Timothy S. Miles
Abstract: We 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.
Keywords: Hand; Muscle, Skeletal; Pyramidal Tracts; Humans; Electromyography; Electric Stimulation; Electroshock; Volition; Reaction Time; Evoked Potentials, Motor; Muscle Fatigue; Neuronal Plasticity; Adolescent; Adult; Middle Aged; Female; Male; Physical Exertion
Description: Copyright © 2002 the American Physiological Society
RMID: 0020020080
DOI: 10.1152/japplphysiol.00835.2001
Published version:
Appears in Collections:Physiology publications

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