Sports and Immunity

Abstract

There is a general consensus that regular exercise of moderate intensity is beneficial for reducing the risk of infection, especially in older adults and people with chronic diseases. In contrast, the burden of infection is reported to increase in high performance athletes during periods of intense training and is the second most common cause, after injury, of missed training days during preparation for major sporting events. This has shaped the common perception that strenuous exercise, which is more like an overload and does not allow sufficient regeneration, can temporarily suppress immunity. At the cellular level, acute exercise induce intensity-dependent leukocytosis which is followed by a redistribution of effector cells into the peripheral tissues. These processes result from the activation of the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis, as well as the associated release of stress hormones such as catecholamines and glucocorticoids. It is assumed that the effector cells strengthen immunological barriers, such as the lungs and intestines, and initiate repair processes, for example in tissues that are stressed or damaged by exercise (e. g. muscles). Regular physical activity thereby mediates a favourable composition of the T-cell compartment, NK cells and monocytes, and improves the function of various leukocyte subpopulations over the entire lifespan. In addition, each single activity releases myokins from the muscles, which have numerous metabolic and immune-regulating effects. In summary, physical activity represents a key or additive behavioural intervention that has the potential to mediate numerous positive effects in the prevention and treatment of the most important lifestyle-associated diseases.