Advice - How to adapt your hydration and nutrition for trail running

You should not overlook the importance of hydration and nutrition before, during and after exercise.

Without doubt, it is necessary to have suitable equipment for trail running. However, you cannot forget that you are the engine! It is common to talk about the importance of training to be successful, you should absolutely not overlook the importance of hydration and nutrition before, during and after exercise.




The human body is composed of 60 to 70% water. As a result, water is the second most vital element for humans (after oxygen of course). It is therefore very important to stay hydrated on a daily basis, especially when you practice a sport in a sustained way. It is recommended to drink at least 1.5L of water per day. In very cold weather, it may be the case that you do not feel dehydrated, but you must still force yourself to drink before you are thirsty.



All athletes know that hydration is a key performance factor that should not be neglected because it can really influence performance (for example: 2% water loss = 20% performance decrease).

In training hydration must be the same as in a race so that you are used to your hydration strategy. It is also important to ensure that the body responds well to the absorption of the product you are using during exercise. Be careful with the weather, the hotter it gets and the more you get dehydrated.

Whatever the amount of hydration in relation to effort you need, it is essential to drink before being thirsty. Isostar's experts advise to drink regularly: "every 15-20 minutes in small sips, drink according to the level of effort and the climatic conditions".



Note: The average water loss during trail running can vary between 1L and 10L per hour! As well as your performance, good hydration will allow you to limit the risk of muscular injury. It is not enough to drink to hydrate effectively: the drink must be suitable (alcohol and fizzy drinks are generally avoided!).
We cannot emphasize it enough; it is very important to adapt your hydration to the intensity of effort and the weather (high heat, cold, humidity, drought ...).





For an active person, energy needs per day are higher than for a sedentary person. Depending on the level and intensity of activity, but they can be between 2800 to 4500 kcal. Nutritional needs will not be the same either - the protein intake (meat, fish, eggs, should be increased and represent 15% of your diet), fat intake should be reduced to 25%, and carbohydrate will also be higher than those of a sedentary person and will have to be around 60% of the total energy intake.

In racing, the goal is to avoid dehydration and delay the depletion of glycogen stores. A runner will win a race with their legs (training), their head (the mind) but also with their stomach! Here are some tips for trail runners with Isostar products as a suggestion:
Drink regularly in small amounts (3 to 4 sips every 15-20 minutes) alternating isotonic Isostar drink: Fast Hydration, Hydrate & Perform or Long-Distance Energy (for races longer than 2h) with water (with a diluted bicarbonate stick).
- It is essential to refuel regularly. The content of these energy intakes will depend on the intensity and duration of effort.
For 3 to 4 hours, it can mainly be simple sugars (energy gels, Actifood, dried fruits ...) to be consumed every 40 to 45 minutes.
For longer, consumption of complex sugars (energy bars) will be essential. For example, we recommend a 1/2 bar every 30-45 min.
- Over long distances, greater than 6-7 hours, plan to take salty energy to avoid saturation with sweet.
- For people who have a fast running pace, the diet is preferably liquid or semi-solid because it can be difficult to eat and digest solid foods. However, the choice is made according to each person’s experience and tastes.

A basic but essential piece of advice: always test the products you eat during your race during training.


The diet of an athlete before exercise or competition is one of the key performance factors: poor nutrition can lead to hypoglycaemia, dehydration, digestive discomfort and therefore poor performance. Whatever the level of activity, the body must be prepared in order to have the necessary energy and hydration to be able to work at maximum capacity on the day of the race. Do not wait until the day of the event to build up energy or water reserves. Start at least 3 days before the event for your nutritional strategy. Whatever products or the nutritional strategy you use, it is imperative to test them during training sessions and not to wait until the day of the competition to try them.