This weekend at Cozumel 70.3 I solidified the fact that my body can not race in hot and humid climates secondary to not just a "leg cramp" but my legs completely locking up. I was destroyed in Texas in 2015 and again in Madison this past June. This season I had some of the best runs off a swim and a bike including an 18min 5k and a 38min 10k all of which were in the high 60's low 70 degrees. Leading up to Cozumel I've done multiple 70.3 race pace simulations at home with 90min rides at 250watts followed by 6-8miles at a 6:40-6:50 race pace without a problem. I got off the bike again just before the dismount line this weekend and my leg was completely locked up, I couldn't move. I did not over bike (I actually averaged 10 watts less in fear of this happening) I started to jog out of T2 and my legs cramped up again by mile 1. I hobbled the next 3 miles before calling it quits in fear of causing myself harm in another country. I made sure I was adequately hydrated before the race in the 2 days leading up to it. I had 2 x 24oz bottles of EFS and likely an extra 10-15oz of water and Gatorade from aid stations on the bike. My electrolytes (including my sodium) are fine. The only thing I can come up with is that my fluid losses far exceed my fluid intake only when it is hot and humid. From what I've read, the body can't really absorb more than 1.2L per hour at maximum and I was just a few Oz. Shy of that. Maybe it would come down to doing better heat training prior to racing in a hot and humid climate, I really don't know. I am going to do some sweat rate testing in the near future but if anyone has any other suggestions please let me know. Thank you.