Muscle training in muscular dystrophies.

There has been a debate for many years on whether muscular training is beneficial or harmful for patients with myopathic disorders and the role of exercise training in the management of these patients is still controversial. Much of this confusion is because of the lack of well-designed controlled training studies on this heterogenic group of disorders. Because effective therapies are still lacking, the patients have to rely on symptomatic treatment in which continuous physiotherapy plays an important role. There is thus still a need for studies evaluating the short- and long-term effects of muscular training in different types of myopathic disorders. We need to elucidate whether muscular training can increase strength and resistance to fatigue, but most importantly, we need to clarify whether training can improve specific functional abilities of the patient with myopathy. Future studies should give us specific information on what type of training, endurance or strength training, is to be preferred for different myopathies. The effect of strength training in one type of muscle disorder is not directly applicable to another, but is largely dependent on the underlying biological defect. From the studies published so far, high-resistance strength training at submaximal and possibly also at near-maximal levels seem beneficial, at least in the short perspective for slowly progressive myopathic disorders. However, the long-term effects of such training have not been systematically studied. In rapidly progressive myopathies, which are caused by deficient structural proteins such as in Duchenne's muscular dystrophy, the use of high-resistance training is far more controversial and questionable. If exercise regimens are to be used, they should preferably commence in the early stages of the disease, at which time there is still a substantial amount of trainable muscle fibres.