Lengthening contractions are not required to induce protection from contraction-induced muscle injury

Lengthening contractions are not required to induce protection from contraction-induced muscle... Abstract We tested the hypothesis that lengthening contractions and subsequent muscle fiber degeneration and/or regeneration are required to induce exercise-associated protection from lengthening contraction-induced muscle injury. Extensor digitorum longus muscles in anesthetized mice were exposed in situ to repeated lengthening contractions, isometric contractions, or passive stretches. Three days after lengthening contractions, maximum isometric force production was decreased by 55%, and muscle cross sections contained a significant percentage (18%) of injured fibers. Neither isometric contractions nor passive stretches induced a deficit in maximum isometric force or a significant number of injured fibers at 3 days. Two weeks after an initial bout of lengthening contractions, a second identical bout produced a force deficit (19%) and a percentage of injured fibers (5%) that was smaller than those for the initial bout. Isometric contractions and passive stretches also provided protection from lengthening contraction-induced injury 2 wk later (force deficits = 35 and 36%, percentage of injured fibers = 12 and 10%, respectively), although the protection was less than that provided by lengthening contractions. These data indicate that lengthening contractions and fiber degeneration and/or regeneration are not required to induce protection from lengthening contraction-induced injury. mouse extensor digitorum longus fiber degeneration force deficit isometric training passive stretch training Footnotes Financial support was provided by National Institute on Aging Grants AG-06157 and AG-00114. Address for reprint requests and other correspondence: S. V. Brooks, Institute of Gerontology, Univ. of Michigan, Ann Arbor, MI 48109–2007 (E-mail: svbrooks@umich.edu ). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “ advertisement ” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Copyright © 2001 the American Physiological Society http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png AJP - Regulatory, Integrative and Comparative Physiology The American Physiological Society

Lengthening contractions are not required to induce protection from contraction-induced muscle injury

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Publisher
The American Physiological Society
Copyright
Copyright © 2011 the American Physiological Society
ISSN
0363-6119
eISSN
1522-1490
Publisher site
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Abstract

Abstract We tested the hypothesis that lengthening contractions and subsequent muscle fiber degeneration and/or regeneration are required to induce exercise-associated protection from lengthening contraction-induced muscle injury. Extensor digitorum longus muscles in anesthetized mice were exposed in situ to repeated lengthening contractions, isometric contractions, or passive stretches. Three days after lengthening contractions, maximum isometric force production was decreased by 55%, and muscle cross sections contained a significant percentage (18%) of injured fibers. Neither isometric contractions nor passive stretches induced a deficit in maximum isometric force or a significant number of injured fibers at 3 days. Two weeks after an initial bout of lengthening contractions, a second identical bout produced a force deficit (19%) and a percentage of injured fibers (5%) that was smaller than those for the initial bout. Isometric contractions and passive stretches also provided protection from lengthening contraction-induced injury 2 wk later (force deficits = 35 and 36%, percentage of injured fibers = 12 and 10%, respectively), although the protection was less than that provided by lengthening contractions. These data indicate that lengthening contractions and fiber degeneration and/or regeneration are not required to induce protection from lengthening contraction-induced injury. mouse extensor digitorum longus fiber degeneration force deficit isometric training passive stretch training Footnotes Financial support was provided by National Institute on Aging Grants AG-06157 and AG-00114. Address for reprint requests and other correspondence: S. V. Brooks, Institute of Gerontology, Univ. of Michigan, Ann Arbor, MI 48109–2007 (E-mail: svbrooks@umich.edu ). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “ advertisement ” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Copyright © 2001 the American Physiological Society

Journal

AJP - Regulatory, Integrative and Comparative PhysiologyThe American Physiological Society

Published: Jul 1, 2001

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