Because your body has fevers in order to heat up germs to death, and exercise artificially causes your body temperature to rise, it follows as an axiom of symbolic logic that exercise will (or can) help to kill germs.¹
I’ve known this for many years, just through common sense. But it’s hard to find a straight discussion of this issue, even on the Google. Here’s a smattering:
“Dr.” Ed Laskowski (I once knew a trombone player named Laskowski) says, from his Mayo bully pulpit, that in general you shouldn’t exercise if your symptoms are “below the neck.” For now just ignore the metaphysical ambiguity of his statement. At least he’s correct that symptoms “above the neck” – which include fevers – allow for exercise. And although he later advocates “common sense,” he fails to appreciate the real reason why exercise might “help you feel better,” i.e., by killing germs and diseases.
According to the self-discredited Findarticles.com (“This article is not intended to be a substitute for medical advice”), we should be scared of exercise. This piece would be flatly dishonest, if it weren’t so confused. First it says that “Working out when you have a fever can cause your body temperature to rise even higher.” But this is exactly the point! After all, a fever itself does this. Then the article, determined to find as many scare tactics as it can, does a total non-sequitur: “Exercise may cause a virus to invade the heart muscle or pericardium, the sac around the heart.” That makes sense why? Later there is this gem: “If you’re exhausted after a post-illness workout, you may be exercising too hard.” Tell that to Lance Armstrong.
Next we have a Catholic website that obviously specializes in irony, accusing other people of mythical beliefs. Exercise doesn’t eliminate toxins? Well maybe if we ate exercise, then it would. Anyway this article admits that “Fever raises your … body heat. Exercise also does this.” Well, what on Earth do the Catholics think fevers are for? It is not a bad thing that exercise takes some of the burden off your body by raising the heat level for it. Who needs a fever when you have a couple miles of sidewalk?
This hippie website advocates self-destruction, actually suggesting you try to lower your fever, immediately after admitting fevers help kill germs. Moving on.
Finally, Dr. Mirkin talks some sense into the Internet. He points out correctly that athletes regularly have body temperatures at otherwise dangerous fever levels, like 103.8 and 101 and 107.8. Add to this the fact that athletes are healthier than the rest of us, and you shouldn’t be so surprised.
One symptom of illness is that we become slothful, lying around the house, waiting for mothers to bring is soup. Don’t listen to this destructive instinct in your body. When you are ill, engage in a substantial cardiovascular workout, possibly with some heavy lifting.
Science and Math Defeated 