Biomaterial Database

Contraction time and voluntary discharge properties of individual short toe extensor motor units in man. 1979

L Grimby, and J Hannerz, and B Hedman

1. The contraction time and the voluntary discharge properties of forty-five short toe extensor motor units were studied in man. 2. The contraction time of the individual motor unit was studied by using selective electrical nerve stimulation or by averaging the increase in force related to its electromyographic potential in tonic voluntary contraction. 3. Both methods showed a range of contraction times from 40 to 90 ms. 4. The discharge properties of the individual motor unit were studied with e.m.g. techniques, permitting the identification of its potentials during maximum voluntary effort. 5. A motor unit which could be driven continously and had a minimum rate of about 10/s and a maximum rate of about 30/s had a contraction time between 60 and 90 ms. 6. A motor unit which could not be driven continously and had a minimum rate of about 20/s and a maximum rate above 40/s had a contraction time between 40 and 55 ms. 7. A motor unit with intermediate voluntary discharge properties had an intermediate contraction time. 8. It is concluded that each motor unit fires at its fusion frequency in voluntary contraction and that the voluntary discharge frequency range of a motor unit can be used as an indication of its contraction time.

UI	MeSH Term	Description	Entries
D009046	Motor Neurons	Neurons which activate MUSCLE CELLS.	Neurons, Motor,Alpha Motorneurons,Motoneurons,Motor Neurons, Alpha,Neurons, Alpha Motor,Alpha Motor Neuron,Alpha Motor Neurons,Alpha Motorneuron,Motoneuron,Motor Neuron,Motor Neuron, Alpha,Motorneuron, Alpha,Motorneurons, Alpha,Neuron, Alpha Motor,Neuron, Motor
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D009431	Neural Conduction	The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.	Nerve Conduction,Conduction, Nerve,Conduction, Neural,Conductions, Nerve,Conductions, Neural,Nerve Conductions,Neural Conductions
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
D014034	Toes	Any one of five terminal digits of the vertebrate FOOT.	Toe