Stay as cool as you can. We encourage you to take generous amounts of water, up to 12 ounces an hour for at least a few hours before the race. Stop at each water station, take a cup of water, pour some over your head if you're feeling warm, and run through the hose sprays located along the course. Dress Properly Do not overdress. The crowd generates heat, and you will warm up as you run.
Extra clothing can lead to heat stroke.
This doesn't mean you should run naked, but it does mean you should feel a bit cool at the start. A visor helps if it's sunny. If you do become weak or dizzy, walk or sit down and rest, or seek out one of the medical aid stations that are near each water aid station. If you have high blood pressure, a heart problem, diabetes or other major health problems, you should clear participation in Bloomsday with your private physician and list any health problems on the back of your runner number. The Bloomsday course is monitored to control traffic.