What role does IgG play in Sport?

IgG (Immunoglobulin G) is an antibody that plays a central role in the immune system, particularly in defending against bacteria and viruses. In the context of sport, IgG is often discussed in relation to athletes' immune status. Intense and prolonged exercise can lead to temporary immunosuppression, known as the 'open window' phenomenon, where concentrations of immunoglobulins like IgG in saliva or blood may decrease. Some studies suggest that repeated measurements of IgG levels could provide clues about infection risk. However, the evidence for a direct link between IgG levels and athletic performance is weak. IgG testing is not routinely used in sports medicine because individual variability is high and other factors such as nutrition, sleep, and stress play a larger role. MyBody-X DNA tests do not measure current IgG concentrations; they analyze genetic variants. To assess immune status, blood or saliva tests are necessary. In summary: IgG is a marker of immune function, not a direct performance indicator in sport. The evidence is mostly mechanistic and insufficient for personalized training recommendations.