Biomaterial Database

Human muscle fatigue investigated by transcranial magnetic stimulation. 1995

K R Mills, and C C Thomson

University Department of Clinical Neurology, Radcliffe Infirmary, Oxford, UK.

Corticospinal motor output was studied during a 1.5 min maximum isometric voluntary contraction of the first dorsal interosseous muscle in five healthy subjects. Compound muscle action potentials (CMAPs) evoked by suprathreshold magnetic cortical stimuli and by supramaximal ulnar nerve stimuli were compared. On average, force fell to 25% of its initial value, CMAPs from nerve stimuli declined to 58% of initial, but CMAPs from cortical stimuli showed no significant change in amplitude after the first 5 s. It is concluded that there is no marked net change in corticospinal output during fatigue. It is postulated that cortical stimuli engage a subgroup of low threshold, fatigue-resistant motor units which remain active throughout the contraction.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D001921	Brain	The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.	Encephalon
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D014459	Ulnar Nerve	A major nerve of the upper extremity. In humans, the fibers of the ulnar nerve originate in the lower cervical and upper thoracic spinal cord (usually C7 to T1), travel via the medial cord of the brachial plexus, and supply sensory and motor innervation to parts of the hand and forearm.	Nerve, Ulnar,Nerves, Ulnar,Ulnar Nerves
D050781	Transcranial Magnetic Stimulation	A technique that involves the use of electrical coils on the head to generate a brief magnetic field which reaches the CEREBRAL CORTEX. It is coupled with ELECTROMYOGRAPHY response detection to assess cortical excitability by the threshold required to induce MOTOR EVOKED POTENTIALS. This method is also used for BRAIN MAPPING, to study NEUROPHYSIOLOGY, and as a substitute for ELECTROCONVULSIVE THERAPY for treating DEPRESSION. Induction of SEIZURES limits its clinical usage.	Transcranial Magnetic Stimulation, Paired Pulse,Transcranial Magnetic Stimulation, Repetitive,Transcranial Magnetic Stimulation, Single Pulse,Magnetic Stimulation, Transcranial,Magnetic Stimulations, Transcranial,Stimulation, Transcranial Magnetic,Stimulations, Transcranial Magnetic,Transcranial Magnetic Stimulations
D018763	Muscle Fatigue	A state arrived at through prolonged and strong contraction of a muscle. Studies in athletes during prolonged submaximal exercise have shown that muscle fatigue increases in almost direct proportion to the rate of muscle glycogen depletion. Muscle fatigue in short-term maximal exercise is associated with oxygen lack and an increased level of blood and muscle lactic acid, and an accompanying increase in hydrogen-ion concentration in the exercised muscle.	Fatigue, Muscle,Muscular Fatigue,Fatigue, Muscular