And if you do, should you push yourself as hard as ever or take it easy? Will exercise have no effect, or make you feel better or worse?
Two little-known studies that were published a decade ago in the journal Medicine and Science in Sports and Exercise showed results so much in favor of exercise that the researchers themselves were surprised.
The investigators found no difference in symptoms between those who exercised and those who rested. And there was no difference in the time it took to recover from the colds. But when the exercisers assessed their symptoms, people said they felt O.K. and, in some cases, they actually felt better.
Now, Dr. Leonard Kaminsky, an exercise physiologist at Ball State University, and others at Ball State encourage people to exercise when they have colds, at least if they have the type producing symptoms like runny noses and sneezing.
He is more cautious about other types of colds that produce fevers or symptoms below the neck such as chest congestion. Exercising with a head cold is not an issue for athletes, Dr. Kaminsky said, because most of them want to train no matter what. “If anything they tend to push too much,” he said.