by Jesse Kropelnicki

Ed. Note—I don't know about where you are, but it is HOT in Portland, and I hear it's only hotter in California and out in Bend. We're shifting into that period of the year in which you should EXPECT blazing temperatures at your next few races. And if you're headed for Kona, well, the time to start your acclimation is now. Jesse Kropelnicki—head coach at QT2 Systems and coach to several superstars—checks in to remind us how to acclimate.

The IRONMAN World Championship in Kailua-Kona is known for three things: the world’s best endurance athletes, unpredictable winds, and heat/humidity. This heat and humidity is, likely, the most common reason why an athlete does not race to his or her fitness capabilities on that day in October. The lack of a specific and good plan for dealing with extreme conditions, usually, is the main culprit for the underperformance. So, as you prepare for your next hot weather race, be it Kona, Cozumel, or something next season, let’s take a look at some of the primary areas where you can prepare your ability to race up to your fitness.


By Columbus Day, most athletes have said goodbye to the warmth of the summer months, and are beginning to adapt to cooler and crisper weather. How can these athletes prepare to race in the tropical climates of Kona, in October, or Cozumel, at the end of November?

Ideally, athletes will arrive at the race site more than 14 days from race day. Any time an athlete can spend 10 to 14 days (or more!) in the climate of the event, will allow them to actually acclimate to the conditions. This entails training outdoors, during the warmer parts of the day, and sleeping without air conditioning (so long as doing so does not hinder good quality sleep).

But that is a pretty difficult endeavor, what, with work and all. So, if you are unable to arrive two weeks prior to the race, the intent should be to avoid the hot and humid conditions as much as possible upon arrival. You should stay indoors, with the air conditioning on, getting your training done early, during the coolest portion of the day. Arriving within this two-week window, a “No Man’s Land” of sorts, will typically deplete more so than acclimate you, since the body will not have enough time to adjust and adapt to the conditions. The only exception to this is for those who begin their acclimation at home, prior to arriving to the race site. This preparation is highly recommended for most age groupers, who are usually unable to arrive more than 14 days prior to the race. For those from warmer climates, this is pretty simple – focus on ensuring that training time is spent in the sun, and heat of the day, during the final four weeks leading into the race (with the exception of race week, itself).

For those from cooler climates, a few acclimation options do exist. These can be used prior to the event, in order to help the sweat rate and blood plasma changes reach levels that are more beneficial to the race conditions. This requires a two-week period of “layering up,” where practically each and every ride and run is done in warm conditions, either by turning up the heat, in the house, and/or using layers of clothing, above and beyond what would be required in normal conditions, to simulate the expected race conditions. The goal is to get the body to start sweating as soon as possible, and at the rate expected on race day.

One way to monitor whether or not you are sufficiently acclimating is to monitor average overnight heart rate. Take some readings prior to traveling to the race destination, and start comparing them once beginning your acclimation. The goal is to see congruency with the levels seen prior to travel or prior to acclimation. This is indicative of the necessary adaptations for acclimation. Some other acclimation “tricks” include the use of a sauna, immediately prior to a workout, in order to pre-heat the system before the start of the session. Studies have shown that the general use of these tools, when not under training load or linked to a workout, do very little, if anything, to prepare athletes for warm weather racing. But when used in conjunction with a training session, these approaches have the capacity for a tremendous impact on performance. The most important factor in the use of saunas is to ensure that you remain properly hydrated. Athletes with higher sweat rates can lose a tremendous amount of fluid in these conditions. Many athletes can be more sensitive to the humidity than to heat. In these cases, it may be a good idea to buy a humidifier, for use in your home training room, in order to simulate race-day conditions. When taken seriously, these measures can have a tremendously positive impact on your race.

Body Fat

Although rarely discussed with regards to heat and humidity, carrying around a little too much body fat can be the equivalent of wearing a 1/8- to ½-inch thick full body sweater, so to speak. This insulation can have a major impact on both sweat rate and the dissipation of heat. We encourage athletes to reach an optimal body fat level, for their gender and age, by race day, particularly for hot weather races.

Appropriate body fat goals are best determined with the help of a registered dietitian, or certified coach. If you can stand to lose a few pounds, keep in mind that a single pound of weight loss is, typically, worth about one minute, over the course of a 70.3, and two over a full IRONMAN. These metrics do not even take into account the impact of more efficient heat dissipation. Just keep in mind that lower isn’t always better. The objective is to reach your optimal body fat level during race week. Not sooner, and certainly not underweight, which will also have serious and negative effects on your performance.


Clothing can play a significant role in maintaining a heat equilibrium. Be smart! Wear clothing that helps you to remove heat at the same rate, or faster, then you take it on. Although heat is not typically an issue on the bike (due to the convectional cooling that takes place at 20mph), it can still make sense to use a well-vented helmet. Many of the recently developed aero helmets are well-vented, and allow for the ability to spray water on your head, through the vents. But, for those that do not allow this, it may worth using a traditional road helmet, instead. If in doubt, err on the side of caution. Sacrifice the small impact on aerodynamics, in favor of not cooking your head. Many athletes underestimate the amount of heat that can be added to, or removed from your head, based upon your choice of headwear, on both the bike and the run. A white race hat, that can be used to keep melting ice, refilled at each aid station, can really help to dissipate heat.

Heat/moisture wicking clothing is a newer gear item that has recently gained popularity among the triathlon population. Based on my experience with athletes, it seems to work IF kept wet the entire day. The big question with that is, does the cooling impact of these items really come from the material itself, or the fact that the athlete is more conscious of keeping it wet, and—therefore—their body wet. The jury is generally out on this one, and because of that I tend to take the more conservative approach until proven otherwise: let the body do its thing, skin exposed, protected with sunscreen, AND with big focus from the athlete to stay wet as much as possible during the race itself. This means grabbing water at every aid station, and dumping water into the helmet and up and down arms/legs. Hat color and race kit color is another area where athletes can reduce the amount of heat added to the system. Lighter colored clothing reflects more radiant heat than darker colored clothing, and is particularly sensitive around the head.

How to Operate the Engine

In the heat and humidity, heart rate can be your most useful pacing metric. Heart rate can do a very nice job of accounting for potential heat accumulation, when pace, wattage, and perceived exertion may not. When heat accumulation occurs, it is very common to see a dramatic decoupling between pace/power and heart rate. For example, heart rate will continue to increase through the opening miles of a race in hot conditions, while pace/speed slows, or remains steady. This is, typically indicative of accumulating heat more quickly than it is being dissipated. In most cases, holding the intensity constant, while allowing the heart rate to increase, will eventually result in stomach bloating, and an eventual unraveling, due to heat related stress. This leaves the athlete only one option: to slow down and to allow the system to rebalance itself. This deceleration most often takes the form of soft-pedaling and/or walking. The smart athlete makes the most of this unfortunate situation, and uses it as an opportunity to remove as much heat as possible, with water and other cooling options.

Slowing down can be very, very difficult, for the well-trained athlete, who is hard-wired to maintain a pre-determined pace, no matter the conditions or circumstances. Slowing down is pretty unnatural, but an investment that can, certainly, save your day. Most will try to fight it, continuing to push the pace. Most of them will fail, taking on more and more heat. Try as they might, this battle can only last for so long, and has a pretty typical foregone conclusion. Even the toughest of the tough will find themselves walking, cramping, and/or with an upset stomach. Mother Nature has a tendency to win. On the other hand, heart rate based pacing, in hot environments, allows an athlete to identify heat accumulation, and adjust the intensity, accordingly, before it becomes a much larger problem. At QT2 Systems, the motto for hot weather racing is to always “keep a few beats in your pocket—once you use them, there’s no getting them back.”

The most critical—and overlooked—period of a hot weather Ironman is, typically, the final ten miles of the bike, and the first two to three miles of the run. We call this The Pocket. This period (and how you handle it) can make or break your day. After spending several hours with a solid breeze, on the bike, we find ourselves in a stagnant changing tent, with no air circulation. This, alone, adds a tremendous amount of heat, almost immediately. Then, out of T2, into the cheering crowds, to run a marathon. Nine times out of 10, those opening miles of the marathon are being run much faster than is appropriate, only adding more and more heat to the equation. It happens on Ali’I Drive every year, and at an alarming rate. Instead, focus on ‘The Pocket.’ Use this period to make absolutely certain that you are staying cool at all costs. That means slowing down, a bit, towards the end of the bike, focusing on getting wet, and opening up the run at a slower pace than you would normally, while focusing on getting cool. 


Racing in the heat, when not fully acclimated, can be a challenging task for many athletes with higher sweat rates, a poor ability to dissipate heat, and/or those from cooler climates. But all of this is quite manageable, if taken into consideration during the days, weeks, and months leading up to the event. Athletes who are able to arrive early, prepare for the conditions ahead of time, consider the right equipment, and pace themselves appropriately will marginalize the challenge of the heat and humidity. Those who don’t are likely to be left scratching their heads, wondering what wrong, and where. 

Athletes should have a tool box full of the means necessary to overcome any challenging race day situation. The more tools available to an athlete, alongside an understanding of how to use them, the more likely they will be able to overcome obstacles encountered along the way. To this end it becomes quite simple:

  1. Arrive heat acclimated
  2. Make gear choices and pace in a way which will limit, or reduce, the amount of accumulated heat
  3. Remove as much heat as possible throughout the day.

Athletes who are able to do achieve the above three things are much more likely to race to their fitness in hot weather events. Those who don’t, or won’t, should consider other, cooler, races.