So here I am trying to decide whether to bail out on racing this weekend. Predicted heat index values in the upper 90's. My primary concern is not comfort, but medical/safety. I'm 61 years young, no medical issues, but not really in shape. I don't tolerate heat well and have had a couple incidents in my past that I'd like to not repeat. In a typical sprint race in 75* weather I'll come in soaking wet. I've got a cold-pack cool vest being shipped to me today and have a paddock canopy. I just don't know where the line is - how much heat is too much? Any wisdom out there?