Posted by Jacob Fraser

Training in the sub-zero wind chills and icy streets of Chicago winters for “seventy and sunny” in Florida to run a destination race in January sounds like the perfect way to spend a winter weekend, but this dramatic shift in climate can cause runners to have a meltdown during the race. However, there are measures that athletes can take prior to and during the race to minimize the impact of the heat on performance.



Acclimatize Before the Race

Put simply, heat acclimation allows the body to better tolerate exertion in high temperatures. Acclimated athletes have lower heart rate, lower salt content of sweat, lower core temperature and lower sweat rates, resulting in increased athletic performance. In order to fully acclimate to a hot environment athletes need to accumulate 90 to 100 minutes of exercise at a minimum intensity of 50 percent VO2max daily for one to two weeks before racing in a hot environment. Given that it is typically not possible for athletes to arrive at the race destination 10 to 14 days ahead of time, there are a couple of other options that may be employed locally to achieve some of the same effects. First, athletes can do some of their training in conditions that simulate those of their race. This may involve exercising indoors while wearing extra clothing and skipping the fans to simulate a hot environment. It’s uncomfortable, especially at first, but it works.

Another method of acclimatizing at home involves either hot yoga or a sauna to elevate heat stress above the sweating threshold of exercise. Hitting the sauna or hot yoga for 20 to 30 minutes after a workout tricks your body into thinking you did a workout in the heat and you get some of the same adaptations as exercising in a hot environment. To get the greatest acclimatization benefit from hot yoga or a sauna, enter the sauna or hot yoga class without rehydrating. In order for the adaptation process to work, athletes should slowly rehydrate over the course of 3 to 4 hours following high-heat exposure rather than gulping down fluid immediately.


Travel and Arrival Strategies

Athletes should pay extra attention to hydration during the entire week leading up to the race, especially while traveling to their destination and upon arrival. Drinking an electrolyte drink every couple of hours and avoiding alcohol while traveling can help reduce dehydration. Recognize that sudden temperature increases predispose the body to overheating sooner and cause sweat rates to increase. Consequently, athletes should consider basing their hydration plans on what they may have done during the summer, rather than the fluid and electrolyte patterns of their winter training.

If possible, athletes should try to get in an easy run upon arrival. It’s best that race day not be the first time an athlete runs in the heat (and humidity). While this doesn’t necessarily affect the physiology of acclimatization, it does have an impact on perception of effort and just a run or two in the heat can make a big difference in how an athlete feels on race day.


Pacing, Nutrition and Hydration Strategies

Athletes should consider the potential effects of the heat and humidity on their performance and make adjustments to pace expectations, nutrition and hydration plans accordingly. Exercising in a hotter environment than the body is used to puts greater stress on the heart, which means that heart rate and intensity increases (even for reduced paces) and the body burns through carbohydrates faster reducing glycogen stores at a faster rate resulting in earlier onset of fatigue and increased muscle damage. The degree to which heat impacts performance will vary according to an athlete’s level of heat acclimation, ability and fitness. However, in temperatures above 70 degrees it can slow an athlete’s pace anywhere from 40 seconds to 2 minutes per

mile. Additionally, in order to cool the body blood and oxygen is diverted, not only from the muscles, but also from the gut which results in decreased digestion. Consequently, the body isn’t able to absorb as many calories so athletes should reduce their calorie intake during the race and aim to get most of their calories from fluids.


Pre-cooling Tips

Athletes can effectively reduce their core temperatures at the start of the race to delay reaching critical core temperature and the onset of fatigue by employing some of the following techniques. First, in the 24 hours prior to the race athletes should try to maintain a lower resting core temperature by avoiding high-intensity exercise, hot tubs or saunas. Along those lines, athletes can drop their core and skin temperatures pre-race so they don’t feel as hot at the start by spending 10 to 15 minutes in a cool pool, lake, ocean or a cold shower. An icy beverage or slushy will also lower an athletes core temperature and cause athletes to store less heat and at a reduced rate, thereby delaying the onset of heat-induced fatigue. Finally, draping cool towels over the neck is also an effective pre-cooling strategy.


Keeping Cool While Racing

* Athletes should grab an extra cup of water at each aid station and pour cool water on themselves to help pull heat away from their core.

* Wear a visor rather than a hat to allow heat to escape through the top of the head. A visor will help shield an athlete’s face from the sun, as well as prevent salt from running into their eyes if they pour water over their head or run through a cooling station.

* Wear light-colored, loose-fitting, moisture-wicking apparel. Light-colored clothing reflects light and heat, whereas darker clothing absorbs light and traps heat, making an athlete hotter. Additionally, loose-fitting clothing promotes more air circulation keeping athletes cooler.

* Wear sunscreen and/or sun sleeves. Sunburn amplifies heat stress so it is important that athletes protect themselves from getting sunburned. In addition to providing protection from the sun, if athletes pour cool water on UV-protectant arm sleeves, they’ll hold water against the forearms which helps keep an athlete cool. Keeping the skin cool helps reduce the overall impact of heat allowing athletes to exercise harder and longer in a warm environment.


With proper preparation leading up to race day, as well as employing pre-cooling strategies and taking steps to stay cool on the run, athletes can minimize the effects of heat on race performance. Follow the tips above to maximize performance and enjoyment at warm-weather destination races.


Coach Kristan Huenink is a USAT-certified coach with Grit Endurance, Live Grit’s athlete-inspired training community.