Reductions in motoneuron excitability during sustained isometric contractions are dependent on stimulus and contraction intensity
Callum G. Brownstein, Loïc Espeit, Nicolas Royer, Paul Ansdell, Jakob Škarabot, Robin Souron, Thomas Lapole, Guillaume Y. Millet
Abstract
This study measured motoneuron excitability using cervicomedullary evoked potentials conditioned using transcranial magnetic stimulation (TMS-CMEPs) of both small and large amplitudes during sustained low- and high-intensity contractions of the elbow flexors. During the low-intensity task, only the small TMS-CMEP was reduced. During the high-intensity task, both small and large TMS-CMEPs were substantially reduced. These results indicate that repetitively active motoneurons are specifically reduced in excitability compared with less active motoneurons in the same pool.
Topics & Concepts
Isometric exerciseTranscranial magnetic stimulationElectromyographyIntensity (physics)Stimulus (psychology)StimulationMuscle contractionContraction (grammar)NeurosciencePsychologyCardiologyInternal medicineMedicinePhysicsPsychotherapistQuantum mechanicsMuscle activation and electromyography studiesTranscranial Magnetic Stimulation StudiesSpinal Cord Injury Research