Current knowledge and new challenges in exercise immunology

Abstract

Exercise has a significant effect on the regulation of the immune system. Acute bouts of exercise induce an intensity-depen-dent leukocytosis, followed by redistribution of effector cells into peripheral tissues. These processes are a result of the activation of the sympathetic nervous system and the hypothalamic-pitu-itary-adrenal axis, increased hemodynamics, and the release of stress hormones such as catecholamines and glucocorticoids. › During periods of intensive training, athletes frequently report increased symptoms of upper respiratory tract infections (URTI) which may be a result of a stress overload associated with an impairment of mucosal immunity. In contrast, single bouts of short-term or moderate intensity as well as regular exercise training are mainly “immuno-enhancing”. › In this regard, exercise positively affects the composition of the T cell compartment and the function of various leukocyte subpopulations. Regular exercise of moderate intensity also exerts immune-regulating effects during inflammation-associ-ated diseases, such as obesity, type 2 diabetes, or cardiovascular diseases, and counteracts hallmarks of immunosenescence. › Consequently, exercise represents a powerful behavioral intervention that has the potential to improve both immune function and health outcomes in subjects of all ages in prevention and therapy. The present review summarizes the current knowledge, new challenges and future directions in the field of exercise immunology.