Often underestimated or poorly managed, hydration in trail running plays an almost equally important role as training and nutrition. Drinking properly helps to limit cramps and also delay muscle fatigue .
But be careful, drinking only plain water before, during and after running is not enough to avoid dehydration, the body may need more.
So, what should you put in your water bottle to run effectively without pain or a drop in performance? We explain this clearly and practically in this article.
Why is hydration essential in trail running?
Trail running is a demanding sporting activity: the body loses significant amounts of fluid through perspiration.
Dehydration greater than 2% Excess body weight directly affects your physical and cognitive performance . It can cause an increased heart rate, decreased concentration, loss of coordination, a feeling of heavy legs, or premature fatigue .
During a long-distance race, lasting more than 2 hours, electrolytes (sodium, potassium, magnesium , etc. ) are also lost through sweat. A deficiency of these minerals will lead to an electrolyte imbalance, often responsible for muscle cramps (note that proper training is the main reason to avoid cramps).
Your hydration during trail running should therefore allow you to both compensate for water loss and restore mineral levels.
Of course, your needs are not the same for a short race as for an ultra-trail. The longer the race distance, the more crucial strategic hydration becomes to maintain balance and prevent muscle problems.
What drink should I choose to avoid cramps while trail running?
Your body needs sodium, potassium, and magnesium to function properly. Without these elements, there is no fluid balance, no nerve transmission, and no effective muscle contractions. An electrolyte deficiency therefore increases the risk of cramps and fatigue .
Despite its hydrating properties, pure water is not enough to compensate for mineral loss . That's why drinks containing electrolytes and sugar are preferable.
Composed of a balanced amount of fast-acting sugars and minerals, they are more effective in limiting the occurrence of cramps. and maintain energy over time .
Here's what you can drink to reduce the risk of cramps :
Mineral waters (such as Hépar, Vichy Célestins or St-Yorre)
● Advantages: natural source of sodium
● Limitations: low in sugar, therefore not very suitable during exercise but ideal before/after
Homemade drinks (water, lemon, honey or powdered sugar, salt)
● Advantages: economical, natural, easy to make
● Limitations: approximate mineral dosage; digestive tolerance needs to be tested
Commercially prepared drinks (tablets/powders)
● Advantages: formulated for targeted carbohydrate and electrolyte intake; convenient to take with you
● Limitations: sometimes too sweet or poorly tolerated; may contain additives.
Some studies suggest that the Sodium bicarbonate , which occurs naturally or is added to some liquids, may help reduce muscle acidity and fatigue. Its direct effectiveness on cramps, however, remains a subject of debate.
Finally, Hydratis tablets offer a simple and reliable solution. Easy to dissolve in a water bottle or flask, they provide a good supply of electrolytes and trace elements (zinc, manganese) with a very small dose of sugars to aid digestion. A practical and comprehensive alternative, useful before, during, and after races.
How to properly hydrate before a trail run to avoid cramps?
Anticipating fluid and mineral losses is the best strategy to reduce the risk of muscle fatigue and cramps.
Proper hydration in trail running therefore begins several days before the race .
From three days before until the day before, drink at least 1.6 to 2 liters per day, divided into small amounts throughout the day , even if you don't feel thirsty. Frequent, clear urine is a good indicator of sufficient fluid intake.
Race day:
● Two to four hours before the start, you can consume between 5 and 7 ml of liquid per kilogram of body weight. This equates to approximately 350 ml to 500 ml of water for a 70 kg trail runner.
● One to two hours before, an additional intake of 150 ml to 200 ml may be considered.
During this preparation phase:
● Opt for beverages rich in sodium or other electrolytes.
● Focus on foods that contain sufficient potassium (bananas, potatoes, green vegetables … ) and magnesium (almonds, legumes, dark chocolate … ).
● The consumption of gels , fruit pastes, and energy compote can also be combined with an electrolyte drink
Hydration strategy during a trail run: when and how much to drink?
Drink when thirsty or at regular intervals?
During a trail run, certain signs should alert you: dry throat, pasty mouth, shortness of breath, dizziness, sudden fatigue … However, waiting until you are thirsty is already a sign of dehydration .
For races lasting more than two hours, follow a strict hydration plan, adapting it according to the weather, the difficulty of the terrain, and the altitude. Ideally, you should drink 150 to 250 ml every 15-20 minutes, even if you don't feel thirsty.
Warning: Drinking excessive amounts of plain water can dilute the concentration of sodium in the blood. This phenomenon, called Hyponatremia can have serious consequences (swelling, confusion, seizures, loss of consciousness, coma ... ).
To avoid this, it is best to drink a beverage containing sodium while exercising.
Transporting water efficiently: which solution to choose?
Choosing the right container is essential for proper hydration.
Soft flasks are lightweight, easy to fill, and ideal for short trail runs. Their only limitation: a small capacity that necessitates frequent refills.
A water bladder or camelback, on the other hand, is more suitable for long distances and ultras without refueling points, because it offers a larger capacity (up to 2 L).
To easily carry your containers during your trail runs, opt for suitable equipment.
For short trips, choose a hydration belt or vest . For longer distances, opt for a hydration pack with front pockets for flasks and a back pocket.
The price of each of these accessories varies depending on the quality of the materials and features. In any case, invest in a reliable system to avoid leaks or discomfort during a competition.
Post-trail hydration: how to recover properly and reduce the risk of cramps?
At the end of the course, the objective is clear: you must replenish your water and electrolyte levels. to help your body recover.
In the hour that follows, it is crucial to consume a significant amount of electrolytes . The goal is to replenish water, electrolytes, as well as carbohydrates and proteins.
Natural fruit juices, salted vegetable broths, smoothies … are also alternatives that you can absolutely use.
To determine how much water to drink after exercise, weigh yourself before and after without your clothes. The difference represents the amount of water lost during the trail run. It is recommended to drink 1.5 times this amount .
For example, if you have lost 2 kg, you should then consume 1.5 L x 2, or 3 L of fluid, to replenish your intake. Don't drink it all at once; spread your intake over 2 to 4 hours.
Finally, as we mentioned earlier, don't forget minerals such as magnesium, potassium, sodium, and calcium . They are also essential for better muscle function restoration and preventing post-trail cramps.
Conclusion
In short, proper hydration in trail running isn't something you can just wing. It's a strategy to plan ahead, adjust during, and continue afterward. It determines not only your performance but also your recovery .
Plain water alone is not enough to meet the needs of a body subjected to intense exertion. It is essential to replenish lost minerals by choosing drinks suited to your needs .
Bibliography
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