Effect of exercise training on chronic inflammation.

Persistent, sub-clinical inflammation, as indicated by higher circulating levels of inflammatory mediators, is a prominent risk factor for several chronic diseases, as well as aging-related disability. As such, the inflammatory pathway is a potential therapeutic target for lifestyle interventions designed to reduce disease and disability. Physical exercise is well recognized as an important strategy for reducing the risk of chronic disease, and recent research has focused on its role in the improvement of the inflammatory profile. This review summarizes the evidence for and against the role of increasing physical activity in the reduction of chronic inflammation. Large population-based cohort studies consistently show an inverse association between markers of systemic inflammation and physical activity or fitness status, and data from several small-scale intervention studies support that exercise training diminishes inflammation. However, data from large, randomized, controlled trials designed to definitively test the effects of exercise training on inflammation are limited, and results are inconclusive. Future studies are needed to refine our understanding of the effects of exercise training on systemic low-grade inflammation, the magnitude of such an effect, and the amount of exercise necessary to elicit clinically meaningful changes in the deleterious association between inflammation and disease.