The last time I had a UTI, my pharmacist warned me the the antibiotic I was given made muscle tears more probable. He said to lay off on strenuous exercise for a while. By no means did he tell me to lay off altogether - just to take it easy. (He knew I was riding my bike home.)

In my opinion, it's good to listen to my body and let it tell me what it wants to do when I'm sick. If I'm feeling crappy and I want to lay on the couch, then I take a day off exercise and lay on the couch. But if I've got the energy, then I go ahead and work out.

I've been exercising regularly for so long that when I have to abruptly stop due to illness, I think that I feel worse from the lack of exercise and being cooped up inside than I do from the sickness itself.