Exercise (or exercise-training), a subcategory of physical activity, is planned, structured, repetitive and intentional bodily movements intended to improve or maintain one or more components of physical fitness
Regular moderate-intensity exercise diminishes the risk of infection. Exercise allows immune cells to perform effectively — it increases blood flow, reduces stress and inflammation, and can strengthen antibodies.
Strenuous exercise leads to the activation of several cell lines within the immune system, such as neutrophils, monocytes, and macrophages, which all are capable of producing ROS (reactive oxygen species).
Neutrophil concentrations increase during and after exercise, whereas lymphocyte concentrations increase during exercise and fall below pre-values after long-duration physical work (Sports Med 6: 333–363, 1988).
Neutrophils are phagocytes that play an important role in the innate immune response, usually being the first cell type recruited to the infection site. Thus, they are involved in many of the inflammatory processes, including those in muscular tissue, promoted by the exercise.
Exercise may also increase the production of macrophages that assaulting bacteria, associated with upper respiratory tract diseases.
Exercise and immune system
