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Heat: Secret Weapon? (Part 1)

author : alicefoeller

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Updated: Make hot weather your secret weapon by understanding how it affects you.

Updated Aug. 31, 2020

Part 1: Why Do You Feel so Terrible When It's Hot?

There's no doubt that a beautiful, smooth 10K run can turn into miserable punishment when the thermometer creeps up. Understanding why you feel worse in the heat can be key to minimizing the effects. And performing well in the heat will give you a hidden advantage over other athletes in your age category.

So, why do we feel so crummy when it's hot?

In short, when both our core temperature AND the air around us are hotter than usual, our bodies need to turn attention to cooling off in order to avoid shutting down. We are warm-blooded mammals, after all. We can't just put our systems on hold in temperature extremes and wake up again when it's more temperate. Our bodies need to maintain themselves within a certain temperature range in order to survive.

So let's say we are doing a long training session, and there are some normal delays getting out the door because, well, it's 2020 and there could be an asteroid coming. The sun is almost directly overhead, but we are just starting out on a run, which is often the hottest part of triathlon no matter the weather. (The swim obviously has the water to cool us, and on the bike we have the wind generated by our forward movement.)

When our body senses it needs to cool off -- but our determined triathlete selves continue to run without stopping -- our body switches gears and begins to do a few things. The main thing that happens is blood is diverted to the surface of our skin, where it should be able to cool off before returning to our heart and lungs. If our skin is sweaty or doused with water, the blood at the surface cools quickly and keeps us from dying. However, the more blood that needs to be diverted to this cooling mechanism, the less is available for other things.

Areas that don't receive enough blood flow when our body is trying to stay cool include:

Our muscles. (This is why it feels so much harder to bike and run when it's hot, even when we are in good shape.)

Our digestive system. It will be harder to eat and even to drink enough when it's hot, because our stomach can't handle the input with such low blood flow to the digestive system. Remember, blood flow to the digestive system is already low when we are working hard, which is why we are more likely to become queasy eating a Clif bar while riding hard than while sitting at the kitchen table. (See Part 2.)

Our brain. Our ability to make decisions and recognize when something is not right will be impaired when we are too hot. This may cause us to make poor decisions that make things even worse. (More on this in Part 3.)

In addition to reduced blood flow, our heart rate is also higher as our body is racing to fulfill these competing needs. So our perceived exertion is higher, and our ability to take on food and water is impacted by our higher heart rate.

I'll provide more specific tips on combating the effects of heat on digestion, brain function and core temperature in future installments. For now, a basic training tip is to practice how you are going to race.

Tips:

If you always run at 6 a.m., you will not be prepared to run later in the morning in a sprint or Olympic distance triathlon. You certainly won't cope well with the afternoon heat of a half-ironman run.

You can't rearrange your whole life to accommodate hot weather training and racing, but do make sure you have trained in the heat before you get to race day.

The tips in the next installments of our heat series will help, but you need to practice them in training so they will be easy to implement. Remember, your brain function is also going to be impacted by the heat, so don't expect to be able to remember and implement something you read in an article. Make it a habit to inventory your body systems and implement heat-response techniques in a stressful race.

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