Running a marathon or doing other long, strenuous races or workouts probably doesn’t temporarily suppress the immune system and increase vulnerability to colds and other infections, contrary to the widespread belief among athletes and researchers, according to a 2018 research review in Frontiers in Immunology.
Most early studies linking grueling endurance exercise to higher rates of illness afterwards depended on self-reports of cold-like symptoms by athletes, which can be inaccurate. But later studies that actually tested saliva for the presence of viruses or bacteria after marathons have found that the runners were no more likely to be infected than the general population. And newer analyses of changes in the immune system in humans and lab animals after endurance exercise suggest that immunity is not suppressed and may actually be enhanced, the British authors concluded.
This article first appeared in the UC Berkeley Wellness Letter.
Also see Answers About Immunity.