Physical exercise as a treatment for adult and juvenile myositis.

There is growing evidence to support the safety and efficacy of exercise in patients with adult and juvenile idiopathic inflammatory myopathies. Five randomized controlled trials including adult patients with polymyositis and dermatomyositis (DM) and additional open studies have demonstrated reduced impairment and activity limitation as well as improved quality of life. In addition, recent studies have shown reduced disease activity assessed by consensus disease activity measures and reduced expression of genes regulating inflammation and fibrosis. Furthermore, exercise could improve muscle aerobic capacity as shown by increased mitochondrial enzyme activity. These data suggest that intensive aerobic exercise and resistance training could reduce disease activity and inflammation and improve muscle metabolism. Encouraging results have been reported from available open studies including patients with inclusion body myositis (IBM) and juvenile DM, indicating reduced impairment, activity limitation and improved quality of life also in these patients. Larger studies are needed to increase understanding of the effects of exercise in patients with active, recent-onset polymyositis and DM as well as in patients with IBM and juvenile DM.