Molecular effects of exercise in patients with inflammatory rheumatic disease.

Exercise is now known to be beneficial for patients with inflammatory rheumatic disease. In patients with rheumatoid arthritis, exercise can improve physical performance, cardiorespiratory fitness and muscle strength, and reduce disease activity and systemic inflammation, as evidenced by reductions in erythrocyte sedimentation rate and other systemic markers of inflammation. Similar effects on physical performance and cardiorespiratory fitness have been observed in patients with polymyositis and dermatomyositis. Improved muscle performance in these patients is associated with an increased ratio of type I : type II muscle fibers and increased cross-sectional area of type II muscle fibers, suggesting that myositis-affected muscle retains the ability to respond to exercise. In addition, resistance exercise training can reduce the expression of genes involved in inflammation and fibrosis in patients with myositis, and in vitro mechanical loading of chondrocytes can suppress the expression of proinflammatory cytokines, indicating that exercise can also reduce inflammation in the local tissue environment. Further studies of the systemic and local responses underlying exercise-associated improvement in muscle performance, soft tissue integrity and health outcomes are warranted.