Moderate Exercise & Immunity
topic
Moderate-intensity aerobic exercise (40–60% VO2 max, 30–60 minutes, 3–5 days/week) produces consistent enhancements in innate and adaptive immune function — elevating circulating NK cells, neutrophils, and T-lymphocytes during exercise and in the hours following (the immune surveillance effect), improving macrophage phagocytic function, enhancing mucosal IgA secretion (the primary respiratory tract immune defense), and reducing systemic inflammatory markers (CRP, IL-6, TNF-alpha) chronically in regularly active versus sedentary individuals.
Role
The immune-enhancing effects of moderate exercise are the most directly relevant to everyday health outcomes — reducing the frequency and duration of upper respiratory infections (the illnesses that account for the most lost work and school days globally) through mechanisms that most people manage with vitamin C and zinc without any awareness that their daily movement habits are a far more potent immune intervention. The 50% reduction in upper respiratory infection risk in people exercising moderately versus sedentary individuals is a larger protective effect than most nutritional supplements can demonstrate — yet it is not marketed to the public in the way that immune supplements are.