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PMID: 2352193 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't

Effects of immobilization on contractile properties, recruitment and firing rates of human motor units.

The Journal of physiology ·Vol. 422 ·1990-03-00 ·Pages 55-65

Duchateau J, Hainaut K

Abstract

1. The contractile properties, recruitment and firing rates of motor units from the human adductor pollicis and the first dorsal interosseous were studied during voluntary isometric contractions after 6-8 weeks' immobilization of the corresponding limbs. 2. In both muscles, motor units of different force thresholds showed a proportionally identical twitch tension decrease and slowing of their time course after immobilization. 3. When expressed as a percentage of the maximal voluntary contraction, more high-threshold motor units were recorded in disused muscles than in control muscles, but the order of recruitment was maintained. 4. The motor unit firing rate at recruitment was identical in control and disused muscles, but the maximal firing rate decreased in all motor units after immobilization. This decrease of the maximal firing rate was greater in motor units of lower threshold than in those of higher threshold. 5. The results further document motoneuronal plasticity in human muscles of different fibre type composition.

MeSH Terms

Action Potentials/physiology Adult Biomechanical Phenomena Female Hand/physiology Humans Immobilization/physiology Male Motor Neurons/physiology Muscle Contraction/physiology Muscles/innervation Sensory Thresholds/physiology Time Factors

Authors & Affiliations

2 authors, click to expand affiliations / ORCID

Duchateau J

Laboratory of Biology, University of Brussels, Belgium.

Hainaut K

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Article Info

Journal

The Journal of physiology

Abbr.

J Physiol

ISSN

0022-3751

DOI

10.1113/jphysiol.1990.sp017972

Published

1990-03-00

Pages

55-65

Language

English

Region

England

NLM ID

0266262

PMCID

PMC1190120

Subset

External Links

PubMed source DOI: 10.1113/jphysiol.1990.sp017972 PMC Full Text View journal details

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Effects of immobilization on contractile properties, recruitment and firing rates of human motor units.

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