Physical exercise as a modulator of the immune system

Background:  Regular moderate physical activity is one of the main strategies for activating the immune system, contributing to the prevention of numerous non-communicable chronic diseases, such as type 2 diabetes mellitus.(2) Methods: This is a literature review based on a selection of five articles published in the last five years, retrieved from the BVS portal and PUBMED databases. (3) Results: Regular moderate-intensity exercise strengthens the immune system by increasing defense cells (neutrophils, macrophages, T lymphocytes, and NK cells) and enhancing their functions through hormones and adhesion molecules. Furthermore, it promotes the release of anti-inflammatory myokines (IL-6, IL-10) and reduces pro-inflammatory mediators (IL-18, TNFα). These effects improve the COVID-19 vaccine response and contribute to the control of chronic cardiovascular and metabolic diseases. Conversely, high-intensity exercise can cause immunosuppression, a higher risk of respiratory infections, and serious cardiovascular events. (4) Conclusions: Moderate and consistent exercise is essential for activating and maintaining the immune system. However, strenuous exercise can pose cardiovascular and infectious risks.