WHAT WATER SHOULD YOU CHOOSE FOR MOUNTAIN RUNNING? A HYDRATION GUIDE FOR TRAIL RUNNERS

The importance of water in trail running

In a mountain race, water is much more than just a drink to quench your thirst. It is essential for maintaining physical performance, regulating body temperature and enabling the body to function properly.

During training or racing, we lose water and minerals through sweat. If those losses are not replaced properly, dehydration can set in, performance drops and the risk of cramps, early fatigue or more serious heat-related problems increases.

That is why learning how to hydrate properly is every bit as important as training.

Is all water the same?

Although they may look the same at first glance, different waters contain different amounts of dissolved minerals, such as calcium, magnesium, sodium and bicarbonates.

One way to tell them apart is by their dry residue: the amount of minerals left behind after one litre of water has evaporated.

In general, you may come across:

• Very low-mineral water.
• Low-mineral water.
• Medium-mineral water.
• High-mineral water.

Each has different characteristics and may be suitable in different contexts.

What water is best for a mountain runner?

For day-to-day hydration, any good-quality drinking water can be a perfectly good option.

However, when it comes to long training sessions or mountain races, particularly in hot conditions, your needs change.

Prolonged exertion leads to significant losses of fluids and electrolytes, particularly sodium. In these situations, it is often advisable to combine good hydration with isotonic drinks or electrolyte solutions, as well as water.

The aim is not only to replace fluids, but also to recover some of the minerals lost during exercise.

How much water do we need?

There is no one-size-fits-all amount.

Hydration needs depend on factors such as:

• Body weight.
• Temperature and humidity.
• Training duration.
• Exercise intensity.
• How much each runner sweats.

As a general reference, an adult needs roughly 30 to 35 millilitres of water per kilogram of body weight per day, although this increases considerably when taking part in sport.

The most important thing is not to wait until you feel thirsty. By the time thirst appears, the body has already started to become dehydrated.

How to stay hydrated before, during and after running

Before training

It is best to start your activity well hydrated. Drinking water regularly in the hours beforehand is far more effective than trying to make up for it just before you head out.

During the race

In long events or high temperatures, it is advisable to drink small amounts frequently.

If the exercise lasts for around an hour or more, or if the conditions are particularly demanding, it may be beneficial to alternate between water and drinks that provide electrolytes and carbohydrates.

After exercise

Recovery also starts with hydration.

A good approach is to gradually replace the fluids you have lost and support that hydration with balanced nutrition to aid muscle recovery.

What about tap water?

In many places, tap water is perfectly safe to drink and meets strict quality standards.

If it is safe to drink and suitable for human consumption, it can be a perfectly valid option for daily hydration.

In any case, during intense or long-duration activity, the key is not so much where the water comes from as maintaining proper hydration and replacing the electrolytes lost through sweat.

Hydration needs training too

Many runners spend months building up their endurance, strength or race strategy, but forget to practise staying hydrated.

Testing different drinking strategies during training, learning how much you sweat and finding out which type of drink suits you best will help you approach race day with much more confidence.

Out on the trails, good hydration is one of those small details that can make a big difference between finishing strong and struggling before the end.