Triathlon racing in heat | Hiddit Triathlon Nutrition

Jun 27, 2019 11:50:24 AM
3 min read

Heat changes how you should race 

What happens yo your body in high temperatures

The first thing to realize is that your body is designed to function at a certain temperature, and if it shows signs of overheating, it will attempt to cool down by by moving a lot of blood to the surface of your body, where it can be cooled down by sweating.

This is an efficient mechanism, but it also means that it takes blood away from your working muscles, and that less oxygen will be available. Your internal athletic engine will become 'muzzled'.

This will automatically result in higher heart rates for the same performance in colder temperatures.

Add to this the fact that dehydration also raises your heart rate, and you can easily see that performing in heat will be more difficult than in cooler temperatures.

But with some planning and adaptations, you can still race in an efficient and safe way.

Follow the tips below.

pro triathlete hydrating

You can learn more about general principles of triathlon nutrition here, or dive deeper in hydration here, but let's focus on what is specific for triathlon racing in high temperatures.

Sodium loading


As you know, you sweat out a lot of sodium (salt), so the more you sweat, the more sodium is lost. Sodium is essential to hydrate and digest glucose, and depleting it can even cause a life threatening condition of hyponatremia.

If you've read our blog on our Isotonic drinks, you will know that they contain the same ratio of sodium as lost in sweat (830 mg/liter), so during the race you can top up the sodium stores.

However, if you are facing a hot race, start sodium loading a few days before. Use sodium-rich Isotonic drinks already three days before, add extra salt to your food and aim for an intake of 3000 - 4000 mg of sodium during the last 18-24 hours prerace.

Sodium does not equal salt: only about 40% of salt is sodium, so adjust accordingly.

Carbo loading

Remember that your stomach and digestive track will have less blood due to the fact that blood is drawn to the skin to cool down?

That also means it will be harder to digest carbs during the race, so make sure your glycogen stores are filled to the max. You can find more about carbo loading in our free ebook on racing nutrition.

Liquid nutrition

For the same reason, your body will find it harder to digest solid foods. Use as much liquid foods as possible, for instance substitute an Energy Bar by an Energy Gel.

Sodium-containing drinks and gels


Make sure to use an Isotonic drink, designed to quickly replenish fluids and electrolytes. Pay a close attention to sodium content: you should be getting around 900 to 1500 mg of sodium per hour if you are a heavy, salty sweater.

Medium sweaters should aim at 500 to 800 mg, and light sweaters 250 to 500 mg.

Make sure you know what your race organisation will be providing, and check out the nutritionals and sodium content of their products. If they do not provide enough sodium, make sure to bring your own sources, such as our Isotonic or sodium-containing Energy Gels.

Don't overhydrate

Drinking too much, and especially water, can flush sodium from your system but also cause stomach cramps if your stomach and intestines can't handle the volume.

You should have a good idea of what your sweat rate is, ideally in several temperatures, and drink accordingly. As a rule of thumb, a person can take in 800 to 1200 ml of fluids before the stomach gets backed up, but this is of course highly individual.

Lower your pace

Nobody wants to lower their pace after a long preparation period, but shooting for a personal best in extreme heat is not advisable.

Your heart rate will be higher than in cooler temperatures, there is nothing you can do about that.

Stick to your planned heart rate zones, even if it means you'll be going slower.

Cool down

luc racing in heat (1)

Start by dressing appropriately, in light colors and airy fabrics. Don't forget a visor or light hat.

Cool yourself down by throwing water over your head and body, running through the sprinklers or putting ice cubes in your clothing. Run or bike in the shades if you have the option.


Extreme heat will definitely impact your performance - as it will anyone's. However, with proper preparation the days before, and a close attention to nutrition during your race, you can still have a great time racing in a safe and responsible manner.



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