How to Handle the Heat and Humidity in Triathlon

The hot and humid climate is a major challenge for triathletes, who must be careful with their training hours, periodization and hydration.

For many triathletes, one of the worst nightmares is to train and / or compete in situations of heat and very high humidity. Can be so extreme that some athletes end up choosing tests with these characteristics to challenge themselves. Others end up being forced to face these conditions when they move to cities with this type of weather for various reasons such as work or family. Coastal or riverside cities, close to the tropics, usually have this type of characteristic climate. Which is a very typical set up in Asia especially South East Asia

Whatever the reason, compete and train in the humid heat makes everything harder and slower than under normal conditions. The equation is complicated, because these two factors – humidity and heat – are individually responsible for the large drop in performance of athletes and, when combined, these two factors can make a huge mess in the body of an athlete.

All human beings got a limit when it comes to handling high temperature when performing a physical activity. As an athlete gets stronger and faster, it heats up your body and the more your speed increases, the more it approaches this limit. In hot environments, this temperature is reached quicker and, what is worse, at a lower cruise speed than you can perform in colder environments. This is an important point to be understood. In general, an athlete can not compete or train in intense heat at the same pace that he could in places with milder weather.

This limit is further reduced when high humidity is present. One of our coaching consultants and a Master of Sport Science, experience this kind of situation every day as he lives right at the equatorial line. He points out that the preparation of athletes in humid and hot places, such as Singapore, requires specific attention and adjustments.


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The human body has a number of “natural switches” reactions that can reduce the pace and even stop an athlete before a collapse. During competitions and training, it is important that the athlete perceives the signs that he is coming to this point before it happens, so he can avoid it.

Keep an eye on the below

> Rise in heart rate;
> Rise in skin temperature, especially in the abdomen and feet;
> Rise of sweating rate;
> the presence of salt in your clothes and skin;
> Decreasing on your vision range
> Mental Confusion.

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• As your body temperature rises, skin temperature also increases, then you starts sweating;
• In normal conditions, the sweat evaporate, cooling the body. In humid environments, the sweat can not evaporate due to saturation of the air, already thick with water vapor;
• The sweat accumulates on the skin;
• As it doesn’t evaporate, the accumulated sweat on the skin turns at room temperature, further heating the skin and thus the body;
• Your body tries to compensate for all this generating even more sweat, which can not be evaporated;
• The cycle continues until dehydration and collapse of you system and shut down. That is the final resort of your body to reduce its temperature.



Typically, an athlete does not feel thirsty until it begins to lose more than 2% of their body weight in fluids. To compound this situation, many times the athletes despise this situation of high heat and humidity, and when they feel thirsty they are already dehydrated. For this reason, many experienced athletes say: “in long races, always ingest liquids at all aid stations, even if you are not thirsty.” In fact, thirst is a sign of the body saying his state is getting critical. A dehydrated athlete has hampered their blood flow, and only a smaller supply of liquid to produce sweat is available, and consequently, there is less heat exchange with the outside environment. The result is a drastic rise in body temperature, decreased performance and, in extreme cases, abandonment of competition or interruption of training. There are even cases of death in situations of extreme dehydration in these adverse weather conditions.

Our body is not a very efficient machine. About 70% to 80% of muscle energy is transformed into heat, leaving only 20% to 30% to be processed in motion. In hot and humid environments, the use of muscle power may reach only 10%. Genetic predispositions may influence this rate, but studies on the topic have been inconclusive.

In situations of high humidity, the main mechanism of the human body to reduce body temperature is reduced in its effectiveness: perspiration. The evaporation of droplets of sweat produces a drastic reduction of body temperature because heat is taken from the muscles to the skin, which in turn produces sweat to enable heat exchange with the external environment through this evaporation of sweat drops. Evaporation and heat exchange with the environment are responsible for the reduction and maintenance of body temperature at safe levels. Things start to get complicated when the ambient temperature is greater than or close to body temperature (36◦C). At this point, there is no exchange of heat, leaving the whole task to the sweat to cool the body. When an athlete is in a very humid environment, virtually no evaporation happens because the air is already saturated with moisture. Thus, our cooling mechanisms lose almost all its efficacy,

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In fact, extreme temperatures and high humidity can cause the switch body heat inversely with the environment, that is, absorbing heat and raising its temperature. This is the result of blockage of the two main mechanisms that control body temperature. Overheating, or hyperthermia is common in scenarios like this.

It is for these reasons that races like the Hawaii Ironman are so difficult and challenging. For athletes accustomed to the cool and dry conditions, hot humid climate is unforgiving.

Many triathletes live this situation, as is the case of a friend of mine who is an age grouper ironman champion nicknamed Kris. Kris, is one of the best amateur runners in triathlon and has broken 3 hours in the ironman marathon, his PB is 9h07 in a cold weather race, but his performance in the Hawaii Ironman is quite different. In 2010, he went 10:16. He said that “even coming early to Kona, adaptation is difficult for anyone who does all the training during the winter.” Says the athlete that is based in the south hemisphere. Among the tactics used by the athlete, is an interesting train at home on the roll with the heater on, increasing the heat and sweating.

A third element can make a hot and humid day become a traumatic experience for an athlete training or competing: dehydration. The ability to reduce core body temperature also depends on proper hydration. As sweat is the primary cooling source, it requires a minimal amount of water to be evaporated. To get an idea, an athlete, in hot and humid environments, sweats an average from 1 to 2.5 liters per hour. This sweat that evaporated needs to be replaced so that the body continues to function properly.

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