Moderate Exercise Improves Immunity and Decreases Illness Rates

Abstract

Moderate exercise training causes favorable perturbations in immunity and a reduction in incidence of upper-respiratory illness (URI). During each bout of moderate exercise, an enhanced recirculation of immunoglobulins, neutrophils, and natural killer cells occurs that persists for up to 3 hours postexercise. This exercise-induced surge in immune cells from the innate immune system is transient but improves overall surveillance against pathogens. As moderate exercise continues on a near-daily basis for 12 to 15 weeks, the number of symptom days with URI is decreased 25% to 50% compared with randomized sedentary controls. Epidemiological and animal studies support this inverse relationship between URI risk and increased physical activity. Recent evidence indicates that maintaining leanness and a physically active lifestyle during adulthood reduces systemic inflammation, an underlying factor in multiple chronic diseases. The anti-inflammatory influence of near-daily physical activity in lowering C-reactive protein, total blood leukocytes, interleukin-6, and other inflammatory cytokines may play a key role in lowering risk of cardiovascular disease, certain types of cancer, type 2 diabetes, sarcopenia, and dementia.