Exercise in extreme heat places a major thermal burden on the body. As the temperature rises, managing your core temperature becomes the limiting factor for performance, whether cycling, trail running, or road running. (1) Here’s how your body responds and how to precisely adapt your hydration and nutrition strategies. 

Before exercise: Optimizing reserves

• 4 hours before: Consume 5 to 7 ml of water per kilogram of body weight (i.e., 350 to 500 ml for a 70 kg athlete).

• 2 hours before: Add 3 to 5 ml per kilogram if your urine remains dark.

During exercise : Replenish without overloading

Don't rely on thirst, which is a late signal. Establish a routine every 10 to 20 minutes to aim for a volume of 400 ml to 800 ml per hour. Include sodium through electrolytes to dilute or chew, salt capsules, and isotonic drinks.

• Isotonic vs. Hypotonic

In extreme heat, choosing a hypotonic drink (more diluted than a classic isotonic drink) speeds up the passage of water through the intestinal walls.

• The salt trap

Consuming large quantities of plain water exposes you to the risk of hyponatremia (dilution of sodium in the blood). It is essential that your drink contains between : 0.5g and 0.7g of sodium per liter . : (3) 

For this, you can consume our isotonic drink, our jelly gels, or our double-salted flavors. After exercise Gradual rehydration

• The 150% rule: Weigh yourself before and after exercise. For every kilogram lost, you should ingest 150% of that loss in water (e.g., 1 kg lost = 1.5 liters of fluid to replenish over the course of several hours). (4) 

• The protocol: Combine a solution containing

0.7g to 1g : of sodium per liter with salty meals to restore fluid balance. The importance of acclimatization Regular and progressive exposure to heat during your training induces beneficial physiological changes: increased plasma volume, decreased heart rate, and better sodium retention by the sweat glands. By scientifically planning your intake and water volumes, heat becomes a manageable factor.



L'importance de l'acclimatation

Une exposition régulière et progressive à la lors de vos entraînements chaleur induit des modifications physiologiques bénéfiques : augmentation du volume plasmatique, diminution de la fréquence cardiaque et meilleure rétention du sodium par les glandes sudoripares. En planifiant scientifiquement vos apports et vos volumes d'eau, la chaleur devient un paramètre maîtrisable.