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Neural Plasticity
Volume 10 (2003), Issue 1-2, Pages 69-76
http://dx.doi.org/10.1155/NP.2003.69

Principles of Force Gradation in Skeletal Muscles

Department of Medical Physiology, University of Groningen, PO Box 196, Groningen 9700 AD, The Netherlands

Copyright © 2003 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A brief survey is given of how motoneurons and motor units are used for the gradation Of muscle force during motor behavior. Basic properties of motoneurons and muscle fibers, including major kinds of functional specialization along the axis of ‘fast’ vs. ‘slow’, are reviewed. The principles underlying the rate and recruitment gradation of force are described, stressing that the properties of motoneurons and muscle fibers are matched to automate important aspects of the gradation procedure. Recent investigations concerning synaptically evoked changes in the discharge properties of motoneurons receive special attention, including ‘plateau’ currents and, under appropriate conditions, self-sustained ‘plateau’ discharges.