Mistake #3: Dressing inappropriately.
We know your black tri kit is slimming and all, but lighter colors will keep you cooler longer, especially when it comes to headwear (bring the white hat to throw ice cubes in). If you’re used to wearing compression sleeves while racing, skip them in high temps. Consider arm coolers, such as the Zoot IceFil Triathlon Arm Coolers or Craft Body Control ArmCOOLers, which will reduce skin temps and provide protection from the sun. Depending on how your body typically reacts to heat, you may want to wear a normal helmet instead of an aero one. Also, although it’s a small detail, wear low-cut socks.
Tip: While preparing for the Ironman World Championship in 2005, Torbjørn Sindballe tried wearing a latex glove while running, putting ice cubes in it to stay cool. He found a reduction in heart rate, and the ice melted quicker than it did in his hat—showing that the palms emit a lot of heat.