Immobilization-induced changes in motor unit force and fatigability in the cat
Article first published online: 13 OCT 2004
Copyright © 1991 John Wiley & Sons, Inc.
Muscle & Nerve
Volume 14, Issue 6, pages 563–573, June 1991
How to Cite
Robinson, G. A., Enoka, R. M. and Stuart, D. G. (1991), Immobilization-induced changes in motor unit force and fatigability in the cat. Muscle Nerve, 14: 563–573. doi: 10.1002/mus.880140611
- Issue published online: 13 OCT 2004
- Article first published online: 13 OCT 2004
- Manuscript Accepted: 28 MAY 1990
- motor unit;
The purpose of this study was to examine the effects of 3 weeks of immobilization on the mechanical properties of motor units in a cat hindlimb muscle. The muscle, tibialis posterior, was immobilized in a shortened position. Motor units were classified as type FF, F(int), FR, or S. Force, axonal conduction velocity, fatigability, and proportions of motor unit types were compared in control and immobilized muscles. All properties exhibited some change after immobilization, including slower axonal conduction velocities, greater twitch forces, slower twitch contraction times, and greater tetanic forces. In addition, most motor units were less fatigable after immobilization. The number of motor units that could not be included in one of the four classification categories increased significantly after immobilization; these units exhibited normal axon conductivity but failed to produce measurable force or associated EMG. Short-term immobilization induced a variety of physiological adaptations in neuromuscular processes that varied with motor unit type.