Also keep in mind that symptoms can evolve, and what might begin as a runny nose could later become something more serious, like bronchitis or the flu. Proceed with caution, keep tabs on how you’re feeling and skip the workout if you start to feel worse.
“There’s this myth that you can sweat out a virus, but that is a terrible thing to do,” said David Nieman, a professor of biology at Appalachian State University and director of the Human Performance Laboratory at the North Carolina Research Campus. If you’re not feeling well, heavy exercise can exacerbate your symptoms and increase your risk for complications, he said. “It has the potential to really bring you down.”
If your condition does deteriorate, it’s best to rest until the symptoms go away, Dr Nieman said. “Then, gradually get back into the routine,” he added. “Relapse can be common if you get back too quickly and push hard.”
In rare cases, exercising intensely while you’re sick, or even shortly after you’ve recovered, could lead to new or lingering symptoms like exhaustion or unexplained pain. Researchers believe this phenomenon is similar to how some people develop long Covid or chronic fatigue syndrome (also known as myalgic encephalomyelitis, or ME/CFS), which are illnesses that can develop after an acute infection. “It can be serious for a small percentage of people if they push exercise too hard during the illness or soon thereafter,” Dr Nieman said. “You may enter into this unexplained syndrome, and it’s not worth the risk.”
Another unlikely but possible consequence of working out heavily while battling an upper respiratory infection is myocarditis, or inflammation of the heart muscle, which can cause symptoms such as a rapid or abnormal heart beat, chest pain or shortness of breath.
Researchers aren’t entirely sure how common it is to develop these more serious conditions during or after a viral infection, or why the body reacts in this way. But there is speculation, Dr. Nieman said, that the immune system goes into “a strange level” of overdrive that ramps up inflammation.
