Sorry if this was already posted:
http://edition.cnn.com/2009/HEALTH/0...out/index.html
It basically says there's this thing called the "neck rule".. if you're sick above the neck (head cold), you can exercise, but if you're sick below the neck (chest cold) avoid exercise. Of course they said if your head cold is severe, don't exercise too.
It's a good read!

