Adaptations to Exercise Training and Contraction-Induced Muscle Injury in Animal Models of Muscular Dystrophy

Abstract

This article reviews the current status of exercise training and contraction-induced muscle-injury investigations in animal models of muscular dystrophy. Most exercise-training studies have compared the adaptations of normal and dystrophic muscles with exercise. Adaptation of diseased muscle to exercise occurs at many levels, starting with the extracellular matrix, but also involves cytoskeletal architecture, muscle contractility, repair mechanisms, and gene regulation. The majority of exercise-injury investigations have attempted to determine the susceptibility of dystrophin-deficient muscles to contraction-induced injury. There is some evidence in animal models that diseased muscle can adapt and respond to mechanical stress. However, exercise-injury studies show that dystrophic muscles have an increased susceptibility to high mechanical forces. Most of the studies involving exercise training have shown that muscle adaptations in dystrophic animals were qualitatively similar to the adaptations observed in control muscle. Deleterious effects of the dystrophy usually occur only in older animals with advanced muscle fiber degeneration or after high-resistive eccentric training. The main limitations in applying these conclusions to humans are the differences in phenotypic expression between humans and genetically homologous animal models and in the significant biomechanical differences between humans and these animal models.

Creatine monohydrate supplementation does not increase muscle strength, lean body mass, or muscle phosphocreatine in patients with myotonic dystrophy type 1

“…For many patients with muscular dystrophy, an increase in formal physical activity may not always be possible; however, several studies have demonstrated the feasibility and efficacy of moderate-strength exercise-training in patients with muscular dystrophy 5,25 and in animal studies. 4,49 Future studies combining a modified resistance exercise program with CrM supplementation will likely have the best chance of demonstrating significant increases in strength, fat-free mass, and function in patients with muscular dystrophy.…”

Eccentric Exercise in Patients with Chronic Health Conditions: A Systematic Review

“…90,91 Studies using animal models of muscular dystrophy have shown that high-intensity eccentric contractions may indeed have deleterious effects on muscle integrity, especially in older muscles with limited capacity for regeneration. 92 Whereas the use of light resistance training consisting primarily of concentric actions may bring about some benefits, eccentric training does not seem to be appropriate to restore muscle function in these patients.…”

Duchenne Muscular Dystrophy: Experimental models on Physical Therapy

“…The main objective of such motor physical therapy is the prevention of muscle contractures and bone deformities (Strober, 2006). However, motor PT approaches have yielded controversial recommendations (Carter et al, 2002) and there is no consensus regarding the type and intensity of PT (Cup et al, 2007). Just as other muscular dystrophies, DMD is a progressive disorder which causes death by cardiac or respiratory failure.…”