Hydration is a pillar often underestimated in sports nutrition. Yet it directly influences endurance, concentration, coordination and recovery.
Beyond drinking regularly, it is about understanding how to adapt intake to real needs.
1 – What happens during exercise
During training, the body produces heat. To maintain a stable temperature, it triggers sweating.
This mechanism leads to losses:
In water
- In sodium, the main mineral lost in sweat
- In magnesium and potassium (in smaller amounts)
These losses have several effects:
- The blood becomes more “concentrated” so the heart works harder
- The muscles are less well oxygenated
- Body temperature rises faster
A loss of around 2% of body weight can already impact endurance but also concentration.
2 – Knowing your needs
The sweating rate varies enormously from one person to another. On average between 0.5 and 2 liters per hour, but it can be higher in some people.
Two simple tools to better understand yourself:
- Weighing before/after exercise (1 kg lost represents about 1 liter of water)
- Urine color: clear to pale yellow = correct hydration / dark = insufficient hydration
It is a simple indicator, useful daily.
Beyond the amount of water, the composition of sweat also varies. Some people lose a lot of sodium.
Different signs:
- White marks on clothing
- “Salty” skin or face after exercise
- Burning sensation in the eyes (salty sweat)
- Frequent cramps
If you observe these different signs, hydration with water only may be insufficient, especially during long efforts.
3 – Effective hydration
Before exercise:
- 500 ml of water in the 2 to 3 hours before
- About 200 ml close to the effort
A slightly salted drink (by adding table salt or taking electrolytes) may be interesting for people who sweat a lot.
During exercise:
- 150 to 250 ml every 10 to 15 min
Adapt according to duration:
- Less than 45 min: water is sufficient
- 45 min to 1h30: water + minerals (electrolytes)
- More than 1h30: minerals + carbohydrates (be careful to choose an exercise drink containing carbohydrates)
Carbohydrates (30 to 60 g/h) help maintain energy and avoid drops in performance.
After exercise:
After training, the objective is to replenish reserves.
- Drink 1.2 to 1.5 times the losses
- Include sodium in food and/or drinks
Without sodium, part of the water consumed is eliminated more quickly through urine.
4 – The key role of sodium
Sodium is essential for:
- Maintaining fluid balance
- Promoting water absorption
- Preventing cramps related to dehydration
Some simple ways to include it:
- Use isotonic drinks
- Add a pinch of salt to a homemade drink
- Consume salty foods after exercise (soup, broth…)
5 – Adapting hydration to your environment
Heat and humidity greatly increase fluid losses.
- Heat → greatly increased fluid and sodium losses
- Humidity → less effective sweating, faster fatigue
In these conditions:
- Drink more frequently
- Increase electrolyte intake
- Anticipate even before feeling thirsty
Conversely, in winter, the feeling of thirst decreases, but losses are still present. The risk is not drinking enough without realizing it.
6 – Common mistakes
- Starting training already dehydrated
- Drinking only water during long efforts
- Testing a new drink on competition day
- Forgetting that some drinks (alcohol, excessive coffee) can promote dehydration.
Be careful, drinking excessively without sodium intake can lead to dilution of salt in the blood (hyponatremia), especially during very long efforts.
Hydration is a simple but powerful lever. When well managed, it improves endurance, helps better manage effort, optimizes recovery and also limits risks related to fatigue and heat.
More than a habit, it is a strategy in its own right, just like training or nutrition.
Chloé Masson
Nutrition Project Manager
chloemasson.nutrition@gmail.com
See previous nutrition articles :
LIPIDS AND SPORT: UNDERSTANDING GOOD FATS TO IMPROVE PERFORMANCE AND RECOVERY
5 COMMON MYTHS ABOUT SPORTS NUTRITION
SPORT AND DIGESTION : HOW TO AVOID DISCOMFORT?