Hacking The Heat During A Triathlon Or Marathon

Funny things happen when you race in the heat.

As soon as you throw your body into the heat and begin to exercise, you create a need to circulate blood out to the skin for cooling, and this both draws blood away from working muscles and also lowers the amount of blood your heart can pump with each beat. Since evaporative cooling from sweat is the primary mode of heat reduction during exercise, this redistribution of blood to the extremities is combined with loss of fluid and blood volume via sweat, which places additional demand on an already stressed heart.

As blood pressure and cardiac output fall from this drop in blood volume, temperature elevation accelerates, performance is impaired as the body reaches a critical core temperature, and neuromuscular drive and metabolic function subsequently begin to plummet. In other words, the wheels fall off.

So what can you do about?

Can you do anything about it?

You bet.

Not only can you condition your body to maintain a higher blood volume, increased sweat rate, decreased salt in the sweat produced, increased salt store availability, decreased fatigue rate of sweat glands and more rapid onset of sweating, but you can also keep your body’s core temperature cooler during exercise in the heat.

And in this article, you’re going to learn how to be a mad scientist, hack yourself to handle the heat, and throw every possible wrench at your body to keep it from blowing up when the pressure cooker is on.

Body Cooling Gear

Let’s begin with the heat-hacking fashion you can wear: body-cooling sleeves, vests, gloves, grips and if you’re in a triathlon, a well-vented helmet.

The science behind body cooling sleeves is that they block solar radiation and increase sweat evaporation by increasing the surface area of the skin. In addition, the newer sleeves contain Xylitol, a natural sugar-alcohol that produces a cooling sensation when wet.

In 2011, two researchers put CEP arm cooling sleeves to the test in the Ironman Hawaii race in Kona, and found that with just a 30 minute run, there was a significantly lower temperature in the arm with a cool sleeve compared to the arm without. Companies such as Zoot, CEP, and New Balance are among those that now make arm cooling sleeves.

Several studies show that a light-weight body cooling vest could possibly get you even better results: in one study, after nearly 40 minutes of warming up in the heat, participants wearing a body cooling vest ran an average of nearly 13 seconds faster in a 5K, with heart rate 11 beats per minute lower. Since a vest covers an even greater surface area than the sleeves, this could be a better option, or an addition to the sleeves.

But just in case sleeves and a vest aren’t enough for you, back in 2004 two Stanford biologists developed a special grip that maximizes heat transfer through the palms. The palm is a point where a large amount of heat radiation occurs, and blood vessels in the palm surface bring heated blood from the core to be dissipated at the extremities.

If the palm is cooled, the cold blood from the palm is brought back to the core to assist with heat management. While the Stanford “Core Control” device is too bulky to effectively carry in a race (and the price of a decent triathlon bike), by freezing an ice pack and securing it to the hand, you can achieve a similar effect, and the BEX Cool Palms or Trigger Point’s palm cooling device are two such examples. A vest will still extract over three times as much heat as a palm-cooling device, but the latter is more portable and affordable.

If you’re planning on breaking out cooling gear for a long event like an Ironman triathlon, consider the logistical implications – your gear should be kept as cold as possible until you use it, and the grips and vest will only maintain cooling for up to a couple hours. This means that you might wear sleeves on the bike, then add in the vest and grip from a cooler in your transition bag.

No discussion of gear would be complete without addressing head cooling, especially if you’re competing in an event for which you must wear  a helmet. Balancing aerodynamics and cooling in a ventilated aerodynamic helmet is a technological barrier that helmet manufacturers must overcome, since vents, holes or any other gap in the smooth surface of a helmet can significantly increase drag.

So if your event requires head protection, you should choose a well-vented aero helmet, such as the Specialized TT2, or simply wear a road helmet if you’re willing to sacrifice aerodynamics (interestingly, the well vented road helmets will cool the head better than if you didn’t wear a helmet at all).

Heat Acclimation

Now that your warm-weather fashion is set, it’s time to address heat acclimation hacks.

Gradual exposure to repetitive exercise and non-exercise heat stress will produce beneficial physiological adaptations, including improved heat transfer from core to skin, more efficient cardiovascular function, decreased heart rate, skin and body temperature during hot exercise, increased blood volume and less electrolyte loss via kidney filtration.

For cold-weather and Northern climate athletes, preparation for a hot race should begin with frequent exposure to simulated heat, since opportunities to train in the racing environments are not available. For these athletes, there are two options: passive acclimation and active acclimation.

Passive acclimation involves sitting or standing in dry heat saunas or steam rooms to simulate heat, and induces the same cardiovascular and sweat changes without the recovery implications or discomfort that accompany exercise in the heat. Sweat evaporation and cooling efficiency appears to occur most favorably with hot-wet conditions (steam rooms), but both methods will achieve favorable results.

Positive adaptations can occur with as few as 10 days of passive acclimation, but for optimum results, begin passive acclimation 4-8 weeks prior to the race, beginning with 10-15 minutes and gradually working up to 45-50 minute sessions every 1-3 days.

Active acclimation, or exercise in the heat, is crucial for experiencing the physiological and psychological responses to hot weather racing, and can be accomplished via treadmill or cycling sessions in a dry heat sauna, or in a small room with a heater or humidifier under the bike. You can use a steady-state exercise protocol, and if you begin to get too hot to exercise comfortably, you’ll still get results if you stop exercising, or remove the heat, allow the body to cool, and then progress back into the routine when you are ready (this is called “controlled hyperthermia”).

During active acclimation, the elevation of both core and skin temperature is necessary for complete heat adaptation, but the wearing too many extra layers of clothing during these sessions could actually be detrimental. Clothing is semi-permeable to water, so the climate developed under your clothing creates a wator vapor pressure that prevents sweat evaporation and rapidly elevates discomfort and dehydration.

Full benefits of active acclimation can take 45 to 60 minutes of moderate-intensity exercise in the heat for 7-10 consecutive days, or four to five times a week for two to three weeks

For these same cold-weather athletes, arriving early to a hot race such as Ironman Hawaii is highly recommended, but initial exposure to a hot-humid environment can result in lethargy, sleep disturbances, loss of appetite, dehydration, greater discomfort of training and reduced training capacity. After 7-10 days, these responses diminish, assuming the athlete isn’t spending the majority of time in an air-conditioned car or home (for this reason, it is recommend to turn the A/C off).

You can lose the positive benefits of heat acclimation in as few as 7 days, so continue to engage in heat exposure until just 4-6 days before the race, at which point you can begin staying out of the sun and the heat.


Water is the ultimate heat-acclimation hack. Not only does your blood require water to maintain volume, but water can be used to cool the skin and body. Let’s begin with pre-race water immersion.

One study found that torso immersion of elite cyclists in a cold water bath for up to 30 minutes improved subsequent power on the bike, another study found 5 minute cold water immersion to increase power during a heat time trial, and finally, if a cold tub is not available, a combination of a cool air fan and a cooling vest can significantly improve cycling endurance in hot conditions.

Once you’re finished immersing yourself, you can ensure that you are pre-loading with water before your event. A practical way to do this is to drink 15-20 ounces of water 2 hours before you go to bed at night, then another 15-20 ounces of water as soon as you wake. Continue to drink 15-20 ounces of water for every hour leading up to the race, tapering off water consumption about 30 minutes before the race begins.

This form of hyperhydration can be potentially be enhanced through the use of glycerol, a binding agent that allows you to retain extra water, but this practice can be dangerous, and at performance improving efforts is banned by the WADA.

While it may not seem like a sexy, new hack, you’ll definitely want to continue to drink ample amounts of water during your hot weather event.

The American College of Sports Medicine recommends 20-40 ounces of water per hour, but Tim Noakes, author of the book Waterlogged and hydration expert and physiologist, says that performance is optimized when athletes drink according to thirst, and that drinking more or less can impair performance, and produce fluid accumulation in the legs. Based on these recommendations, when you get thirsty during a hot event, you should consume 4-8 ounces of water.

The colder the water you’re drinking the better, since cool fluids leave the stomach more quickly than room-temperature or body-temperature fluids. Finally, there is some evidence to suggest that electrolyte-containing fluids will result in a greater amount of hydration compared to plain water.

Contrary to popular belief, there may not actually be a need for increased electrolyte intake as a heat hack.

Research shows that high sodium intake during exercise may actually increase sodium loss, and the body’s natural stores of sodium may be much higher than the 10 grams frequently cited by electrolyte manufacturers. Therefore, taking in “extra” electrolytes because the weather is hot may simply cause you to sweat or urinate those additional salt. Based on this, it may not be necessary to exceed 2-3g of electrolytes on race day. Ideally, supplementation should contain sodium, chloride, potassium, magnesium, and manganese, from capsules, tablets, powder, or pre-mixed liquids (remember that most gels also contain 80-300mg of electrolytes).

The importance of water “immersion” will continue into the race. Your perception of heat will heavily influence your perceived rate of exertion, and while ice, ice sponges and cold water on the back of the neck, inside the front of the tri suit, or down the legs will not significantly reduce core temperature, these methods can significantly decrease perceived heat.

Finally, water in the form of ice slushies can lower physiological strain and core temperature. To make your own slushies, you can fill a water bottle with crushed ice and if you’re in a triathlon, keep it in a cooler in T1 and in your special needs bag. On the run, you can grab a cup of aid station ice and add 4-6 ounces of water or coke, then chomp down, chew and swallow as you go

Extra Heat Hacks

When it comes to hacking the heat, there are a couple additional considerations that fly under the radar. The first is the propensity of the gut to become more permeable during exercise in the heat, which can cause diarrhea as the body attempts to avoid toxins from gut organisms entering the bloodstream, where they can lead to heatstroke and organ damage.

Enter colostrum, a nutrition supplement extracted from the milk of mother cows and goats, which has been found to reduce gut leakiness by up to 80 percent during maximum aerobic running. Supplementation with colostrum should be initiated at least 2 weeks prior to hot weather competition, and you should be warned that colostrum may increase growth factor levels above that consider acceptable by the WADA.

The final heat-hacking element to consider is sunscreen. Most oil-based sunscreens will limit cooling capability due to creation of a non-porous structure on the skins surface, but a sunscreen made with specific benzones that create a porous polymer can allow the skin to breathe, and enhance cooling. Scape sunscreen is one example of a product that includes Avobenzone as a safe but porous UV-blocker.


So now that you know how to use hydration, colostrum, electrolytes, slushies, gloves, cold baths, porous sunscreen and more to get your body ready for the heat, it’s time go scan the globe for the hottest races on the planet and go try out your new heat hacks.

Have fun out there.

Questions, comments or feedback? Leave them below. And if you want to work with a Superhuman coach to help prepare you for your triathlon, marathon or any other hot weather event, simply request a coach by clicking here.