I did a fast (for me) 26 mile traaining ride at about 98 degrees Tuesday night, then got up Wednesday for a 54 mile club ride that started at about 80 and went up to 100 by the time I finished. I felt completely gassed the rest of the day, and today I've felt weak and listless, with a low-grade headache all day. Since it was over 100 again today I blew off this evening's training ride. I hope I feel better tomorrow.