Heat acclimatization can seem a bit complex, but it's really just the process in which your body adapts to the stress of heat. With the right training and exposure, the strain of high temperatures and humidity (that can send your heart rate through the roof and make your workout feel way harder) lessens.
Properly acclimating to warm temps can be the difference between performing at your best and blasting past the competition in an endurance race and your mind and body shutting down mid-race. Take, for example, the Olympic trials that took place in downtown Los Angeles just a few weeks ago. Shalane Flanagan, though she landed a third-place finish, was incoherent as she fell to the ground with symptoms of heat exhaustion after she crossed the finish line.
"The athletes were struggling because they weren't properly prepared," says Douglas Casa, Ph.D., ATC, CEO of the Korey Stringer Institute and Blueprint for Athletes Medical and Scientific Advisory Board member. "Race temps are usually mid 60s, but it was in the 70s at the start of the trials and rising into the 80s in the middle of the race; plus, nearly every athlete was coming from cool climates like Boulder, CO," he adds.
Even if you're not an Olympian or a professional athlete, it's still smart to acclimate your body before diving in to training in the heat—Whether you've signed up for The Bermuda Triple Challenge in March, want to run an IRONMAN in a warm-weather climate like Puerto Rico, Mexico, or California, or just want to take your workouts outside after being holed up in the gym all winter. Sure 70 to 80 degree weather is a dream if you're paddle boarding or walking along the beach, but training? That's a different story.
For hot weather races, conditioning your body to the heat can mean a 5 percent difference in performance, and anywhere from a 2-3 percent difference in performance in warm weather climates. That's significant if you're running even a medium-distance race like a 10-K (If you typically run 6.2 miles in 60 minutes, for example, you could theoretically shave off 3 minutes by acclimating your body.)
"You can look at heat acclimatization as a natural blood doping," Casa says. "You get an expansion of your plasma volume—about 3-4 percent—when you heat acclimatize so you have more blood that can be shared amongst your heart to maintain your power output, take away toxic waste, deliver oxygen to your muscles, and cool your body down," he adds.
So, ready to start training right?