Running during recovery from hindlimb suspension induces transient muscle injury

Kasper, Christine E.; White, Timothy P.; Maxwell, L. C.

doi:10.1152/jappl.1990.68.2.533

Cited by 76 publications

(82 citation statements)

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“…Injury and repair are likely the normal route of adaptation to increased utilization and stress production in skeletal muscle (34)(35)(36). However, the present study demonstrates that the extent of damage is significantly higher in dystrophic muscle for any given level of stress.…”

Section: Resultsmentioning

confidence: 50%

Dystrophin protects the sarcolemma from stresses developed during muscle contraction.

Petrof

Shrager

Stedman

et al. 1993

Proc. Natl. Acad. Sci. U.S.A.

1,301

1,098

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The protein dystrophin, normally found on the cytoplasmic surface of skeletal muscle cell membranes, is absent in patients with Duchenne muscular dystrophy as well as mdx (X-linked muscular dystrophy) mice. Although its primary structure has been determined, the precise functional role of dystrophin remains the subject of speculation. In the present study, we demonstrate that dystrophin-deficient muscle fibers of the mdx mouse exhibit an increased susceptibility to contraction-induced sarcolemmal rupture. The level of sarcolemmal damage is directly correlated with the magnitude of mechanical stress placed upon the membrane during contraction rather than the number of activations of the muscle. These findings strongly support the proposition that the primary function of dystrophin is to provide mechanical reinforcement to the sarcolemma and thereby protect it from the membrane stresses developed during muscle contraction. Furthermore, the methodology used in this study should prove useful in assessing the efficacy of dystrophin gene therapy in the mdx mouse.

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Section: Resultsmentioning

confidence: 50%

Dystrophin protects the sarcolemma from stresses developed during muscle contraction.

Petrof

Shrager

Stedman

et al. 1993

Proc. Natl. Acad. Sci. U.S.A.

1,301

1,098

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“…Among some of the candidates for inducing the activation of these systems are glycocorticoids, the inflammatory cytokines (interleukine-1 and TNF-a) and oxidative stress, which are associated to immobilization-induced atrophy 24,27 . Once the immobilization leads to significant muscular alterations, several authors had an interest to study the effects of exercise programs after this procedure 3,[28][29][30] . The results they found deserve attention, because, although some authors show that exercise program are capable of reversing these alterations 3,29 , there are also reports that the mechanical loading imposed on the atrophied muscle may lead to transient muscular injuries, with impairment of the maximal isometric strength 28,30 .…”

Section: Discussionmentioning

confidence: 99%

“…Once the immobilization leads to significant muscular alterations, several authors had an interest to study the effects of exercise programs after this procedure 3,[28][29][30] . The results they found deserve attention, because, although some authors show that exercise program are capable of reversing these alterations 3,29 , there are also reports that the mechanical loading imposed on the atrophied muscle may lead to transient muscular injuries, with impairment of the maximal isometric strength 28,30 . These contradictory results may be related to the different methodological procedures used in these studies, such as different times of movement restriction imposed to the muscle (between seven days and four weeks), different techniques of muscle load removing (immobilization versus limb suspension), and also different load intensities imposed on the atrophied muscle after immobilization (free mobilization, isokinetic exercise, or walking belt).…”

Section: Discussionmentioning

confidence: 99%

Curto período de imobilização provoca alterações morfométricas e mecânicas no músculo de rato

Lima¹,

Caierão²,

Durigan³

et al. 2007

Rev. bras. fisioter.

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Objective: to analyze the morphometric and mechanical characteristics of the soleus and gastrocnemius muscles after immobilization in a shortened position. Methods: 20 Wistar rats (250 ± 20g) were divided equally into immobilized and control groups. The left hind limb was immobilized by means of an acrylic resin orthosis, with the ankle joint at maximum plantar flexion. After seven days of immobilization, the muscle mass, number and length of sarcomeres in series, muscle fiber cross-sectional area, density of the intramuscular connective tissue area and tensile strength of the triceps surae muscle were evaluated. The data were analyzed by the ANOVA and Tukey tests (p< 0.05). Results: The immobilized soleus muscle presented changes in all the morphometric variables analyzed, while some of these changes were not observed in the gastrocnemius muscle. Analysis of the mechanical test showed that the immobilized group presented a 20% decrease in the maximum tensile muscle strength. Conclusion: The results from this study showed that short-term immobilization causes changes to the morphometric parameters of the muscle fibers, with repercussions on muscle mechanics. These results suggest the need for rehabilitation of muscles subjected to immobilization, even if only for a short period, in order to achieve early recovery of normal muscle characteristics.

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“…In addition, most of the genes downregulated and several genes upregulated during unloading return to basal levels within a few hours of recovery (78). These effects result in relatively rapid recovery of the fiber cross-sectional area (135,138) and muscle mass (15,(136)(137)(138)(139)(140)(141).…”

Section: 1) Myofiber Damage and Recovery Of Muscle Massmentioning

confidence: 99%

Determinants of Disuse-Induced Skeletal Muscle Atrophy: Exercise and Nutrition Countermeasures to Prevent Protein Loss

Bajotto

Shimomura

2006

J Nutr Sci Vitaminol

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Summary Muscle atrophy results from a variety of conditions such as disease states, neuromuscular injuries, disuse, and aging. Absence of gravitational loading during spaceflight or long-term bed rest predisposes humans to undergo substantial loss of muscle mass and, consequently, become unfit and/or unhealthy. Disuse-or inactivity-induced skeletal muscle protein loss takes place by differential modulation of proteolytic and synthetic systems. Transcriptional, translational, and posttranslational events are involved in the regulation of protein synthesis and degradation in myofibers, and these regulatory events are known to be responsive to contractile activity. However, regardless of the numerous studies which have been performed, the intracellular signals that mediate skeletal muscle wasting due to muscular disuse are not completely comprehended. Understanding the triggers of atrophy and the mechanisms that regulate protein loss in unloaded muscles may lead to the development of effective countermeasures such as exercise and dietary intervention. The objective of the present review is to provide a window into the molecular processes that underlie skeletal muscle remodeling and to examine what we know about exercise and nutrition countermeasures designed to minimize muscle atrophy. Key Words Skeletal muscle disuse atrophy, microgravity, hindlimb suspension, protein synthesis and degradation, exercise and nutrition countermeasures Because skeletal muscle is the most abundant tissue of the human body, we may hypothesize that decreases in its mass possibly will profoundly impact the wholebody metabolism and ultimately lead to the development of lifestyle-related diseases. In addition, muscle deconditioning (reduced strength, abnormal reflex patterns, increased fatigability) could limit the ability of astronauts to work in space and/or to rapidly egress the spacecraft in an emergency landing ( 1 ). Even though various functional and morphological alterations are noticeable in inactive muscles, decreased protein content has been regarded as the hallmark of skeletal muscle atrophy. Muscle protein can be either gained or lost by relative changes in protein synthesis and degradation rates, which are known to be modulated by contractile activity. Thus, understanding about the molecular regulators of protein turnover during different mechanical loading conditions and their response to specific treatments leads to the likelihood of developing effective countermeasures for preventing disuseinduced muscle wasting.This article provides a review of muscular adaptations to disuse, with emphasis on protein kinetics. We describe first the general aspects of muscle wasting with regard to exposure to actual or ground-based, simulated microgravity and some of the most significant findings that provide evidence for a close connection between skeletal muscle plasticity and protein metabolism. Next, we present a review of the literature in which results of measurements of protein synthesis/ degradation rates during unloading are avail...

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Running during recovery from hindlimb suspension induces transient muscle injury

Cited by 76 publications

References 0 publications

Dystrophin protects the sarcolemma from stresses developed during muscle contraction.

Dystrophin protects the sarcolemma from stresses developed during muscle contraction.

Curto período de imobilização provoca alterações morfométricas e mecânicas no músculo de rato

Determinants of Disuse-Induced Skeletal Muscle Atrophy: Exercise and Nutrition Countermeasures to Prevent Protein Loss

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