Central fatigue induced by short-lasting finger tapping and isometric tasks: A study of silent periods evoked at spinal and supraspinal levels. (1st October 2015)

• Record Type: Journal Article
• Authors: Arias, P.; Robles-García, V.; Corral-Bergantiños, Y.; Madrid, A.; Espinosa, N.; Valls-Solé, J.; Grieve, K.L.; Oliviero, A.; Cudeiro, J.
• Is Part Of: Neuroscience. Volume 305(2015)
• Page Start: 316
• Page End: 327
• Publication Date: 2015-10-01
• Subjects: 10max-30max 10 or 30 s of maximal mode execution -- CF central fatigue -- CMAP compound muscle action potential -- CMS cervicomedullary stimulation -- comfort 30 s of comfort mode execution -- FDI first dorsal interossesous muscle -- ft finger tapping task -- iso isometric task -- MVC (isometric) maximal voluntary contraction -- ROM range of motion -- SP silent period -- TMS transcranial magnetic stimulation; central fatigue -- repetitive movements -- human; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2015.07.081
• Languages: English
• ISSNs: 0306-4522

Abstract

Highlights: Cervicomedullary stimulation (CMS) explores the spinal cord circuitry functionality. Transcranial magnetic stimulation (TMS) explores spinal and M1 excitability. Tapping rate decreases within 10 s of maximal-rate finger tapping (10 s max ft ). 10 s max ft increases the duration of silent periods induced by TMS. 10 s max ft does not modify the duration CMS silent periods. Abstract: The neural substrates of fatigue induced by muscular activity have been addressed in depth in relation to isometric tasks. For these activities, when fatigue develops, it has been noted that the duration of the silent periods (SPs) increases in response to both transcranial magnetic stimulation (TMS) of primary motor cortex or electric cervicomedullary stimulation (CMS). However, fatigue is known to be task-dependent and the mechanisms giving rise to a decrease in motor performance during brief, fast repetitive tasks have been less studied. We hypothesized that fatigue induced by repetitive fast finger tapping may have physiological mechanisms different from those accounting for fatigue during an isometric contraction, even in cases of matched effort durations. In these tasks, we examined the contribution of spinal and supraspinal motor circuits to the production of fatigue. The tapping rate and maximal voluntary contractions (MVC), and TMS- and CMS-evoked SPs were obtained at the time of fatigue, and while subjects maintained maximal muscle activation after fast finger-tapping (or isometric activity) of different durations (10 or 30 s). Results showed different mechanisms of fatigue triggered by isometric contraction and repetitive movements, even of short duration. Short-lasting repetitive movements induce fatigue within intracortical inhibitory circuits. They increased TMS-SPs, but not CMS-SPs. On the other hand, isometric contraction had a clear impact on spinal circuits. The consideration of these differences might help to optimize the study of fatigue in physiological conditions and neurological disorders.