Many endurance athletes experience cold-like symptoms after strenuous events like marathons, triathlons, or even intense training sessions. This phenomenon, often called “runner’s flu” or “post-race flu,” isn’t necessarily caused by a virus, though it can be. Instead, it’s frequently a direct result of the extreme stress placed on the body during prolonged exertion.
The Science Behind Post-Race Illness
A 2024 meta-analysis in Exercise Immunology Review shows that your risk of an upper respiratory tract infection increases by 18% after running a marathon. This is because endurance events temporarily suppress the immune system. When the body is focused on recovering from extreme physical stress, it prioritizes muscle repair and physiological balance over fighting off infections.
As Dr. Marissa McCay, a sports medicine physician at NewYork-Presbyterian The One/Columbia University Irving Medical Center, explains, “You’re putting your body through a huge feat…so many of its functions are working in overdrive.” This means the immune system may be less effective at preventing viral infections picked up during crowded race environments.
However, not all post-race symptoms are infectious. Dr. Sawalla Guseh, director of the Cardiovascular Performance Program at Mass General, points out that some symptoms are simply the body’s natural inflammatory response to intense exertion. “This is going to affect your muscles, this is going to affect your immune system…they’re all in recovery mode.” Symptoms like a runny nose and cough can be a non-infectious part of this process.
Prevention & Treatment
While the immune system is suppressed, athletes can take simple precautions to lower their risk of contracting an actual virus. These include frequent hand washing, disinfecting surfaces, avoiding touching the face, and considering a mask in crowded settings before and after events.
Beyond hygiene, adequate training and recovery are crucial. Dr. Guseh emphasizes that post-race symptoms can be a sign of inadequate preparation. “Post-marathon symptoms…are really your body’s way of saying you need a little bit more fueling, you need a little bit more electrolytes and recovery.” A well-structured training plan and proper nutrition can help the body better withstand the stress.
If symptoms do occur, rest, hydration, and nutrition remain the most effective treatments. Warm liquids like tea with honey can soothe a sore throat. However, if symptoms persist beyond three days or include confusion, high fever, dark urine, or severe nausea, medical attention is necessary.
At the end of the day, endurance events push the body to its limits. Recognizing this physiological stress and prioritizing recovery is key to minimizing post-race illness.
