Recently my son came down with a bad head cold, and I soon caught it from him. Some combination of echinacea, zinc, extra sleep, and luck probably saved me from a week-long ordeal, because I woke up less than 24 hours after symptoms started feeling well.
The illnesses, though, started some discussions in our household about activity when you’re sick. My assumption about illness was that once you start getting sick, you should rest intensively until you’re better, but it turns out that the experts don’t necessarily agree. A Rodale News article on the subject quotes researcher David C. Nieman saying that people who exercise more get and stay less sick, which may be no surprise, but in the same article Nieman points to research he has done that seems to suggest that moderate exercise when we’re mildly sick (like with a head cold) can cut the length of the illness by half.
Nieman and article author Emily Main are quick to point out that exercising with a chest cold or severe illness is a recipe for trouble, and give pretty specific guidelines on when to exercise during an illness and when not to; read the full article for details.