How to fuel for a trail or ultra trail run?

Are you preparing for a trail run, long trail, or an ultra trail? Managing your nutrition is crucial. It is one of the most common reasons for dropping out. Nutrition in trail running demands special attention and necessitates a deep understanding of oneself. We’ll provide you with essential tips to steer clear of common mistakes and enhance your chances of completing your trail. Here are our recommendations for fueling during a trail or ultra trail run.

The digestive system under strain during long Trail and Ultra Trail running

During long trail and ultra trail running, blood flow is predominantly directed towards the muscles involved in the activity, rather than the digestive system. This redirection of blood flow is a primary cause of digestive issues, as the intestines receive less blood and, consequently, struggle to function effectively.

Another factor contributing to digestive discomfort is the saturation of the stomach with foods that are overly sugary or acidic. To prevent stomach or esophageal irritation, it’s crucial to incorporate a variety of foods into your race-day nutrition.

We will explore strategies for trail nutrition, starting from 2 hours into the race and extending to ultra trails that last between 30 to 45 hours.

Mistakes to avoid in trail nutrition

Hydrate appropriately, but avoid overhydration

A trail runner should optimize their carbohydrate reserves in the days preceding the race. However, it’s equally important not to overindulge in food or drink right before the start. Race day stress can lead to a nervous stomach, so rather than eating excessively, plan to begin nourishing yourself from the first hour of the race.

During the race, taking a few sips every fifteen minutes is advisable. Ideally, aim to consume 500ml (about 17 oz) per hour, or up to 750ml (about 25 oz) in hotter conditions. Overhydration can cause hyponatremia, characterized by an excessively low concentration of sodium in the blood. Its symptoms closely mimic those of dehydration, making it vital to accurately diagnose and avoid further water intake unnecessarily.

Consider the glycemic index of your foods

Paying attention to the glycemic index of the foods you eat is crucial. Foods that are overly sweet and have high glycemic indexes should be avoided. While they may offer an initial energy surge, this can quickly dissipate, leaving you energy-depleted.

Such foods cause a swift increase in blood sugar levels, followed by a rapid decline, which can lead to hypoglycemia. Specifically, it’s advisable to steer clear of consuming energy gels early in the race and to prefer foods with a low glycemic index instead.

Our recommendations for fueling during a Trail or Ultra Trail Run

When preparing for a trail or ultra trail run, it’s useful to focus on the duration of your effort rather than the distance covered. One of the benefits of trail nutrition is the flexibility to eat and drink on the go, without being reliant on aid stations.

Hydration should be a constant priority, with the recommendation to drink regularly, about every 10-15 minutes. While sports drinks can be beneficial, alternating with plain water is also advised. However, be cautious with consuming Coca-Cola for a quick energy boost; its high sugar content and potential for causing a rapid increase in blood sugar levels mean it should not be consumed at every opportunity.

Consider adding mineral or sparkling water enriched with magnesium and sodium to your hydration plan.

For sustenance, aim to alternate between a salty snack and a sweet snack every 30 minutes. If you have a preference at any point, go with the option that is easiest for you to consume. Energy bars are a great choice, with varieties including almonds, fruits, vegetables, and sweet options like compotes made from sweet potato, apple, and others.

For those in search of high-quality nutrition products, Baouw, a brand based in the Alps, offers an array of energy bars and purees worth exploring.

At aid stations, you’ll typically find a range of solid food options such as bananas, raisins, oranges, cheese, sausage, biscuits, and more. It’s important to choose foods that you digest well, avoiding overconsumption in a single sitting.

Soup can also be a good choice, offering both hydration and alkalizing benefits from the vegetables. Some aid stations may offer the option to add rice or pasta to your soup, providing an additional carbohydrate source to fuel your run.

Regular caloric intake during a Trail or Ultra Trail run

Maintaining a regular caloric intake is essential during a trail or ultra trail run. For example, during the Ultra-Trail du Mont-Blanc (UTMB), a runner can burn more than 15,000 kcal! This highlights the importance of consuming food at most aid stations, with an emphasis on variety.

Taking time to chew thoroughly is beneficial, as saliva plays a significant role in the digestion process. It’s also advisable to slow your pace slightly before reaching an aid station. This helps in lowering your heart rate and ensures you’re not too breathless to eat.

If you have the support of friends or family during the race, consider having them prepare homemade foods for you, such as sandwiches, or mashed potatoes mixed with olive oil and salt. While this requires some planning and organization, such comforts can be incredibly beneficial during the long hours of a trail or ultra trail run.

Prepare your Trail or Ultra Trail nutrition plan in advance

To optimize your performance and enjoyment during a trail or ultra trail run, preparing a nutrition plan in advance is key. Start by creating a tailored plan for yourself. Begin with printing the course profile and plotting your estimated passage times. While these estimates may not be exact, they’ll provide a framework based on your target finish time and allow you to analyze previous years’ results to understand the performance of runners at your level. Be wary of basing your plan solely on runners who may have started too aggressively and mismanaged their race; instead, look to those who have paced themselves wisely throughout.

When planning your nutrition and hydration, consider the intervals between aid stations and pack your gear accordingly. As a general guideline, we recommend consuming 500ml of water per hour of running, along with a carbohydrate source every 30 minutes. It’s prudent to pack a little extra to account for any unforeseen delays or extended periods between aid stations.

Tailored Trail training: beyond nutrition

Training for a trail or ultra trail run goes hand in hand with strategic nutrition planning. Your body needs to become accustomed to running long distances and managing periods of glycogen depletion.

An interesting approach to training could involve occasionally reducing your carbohydrate intake during long runs to assess how your body copes with decreased energy reserves. While not advocating for extreme measures, it’s worth noting that elite runners like Kilian Jornet have experimented with running for extended periods without food to explore their physical limits under conditions of scarcity.

Race day is not the time for experimentation with your nutrition or equipment strategy. A well-thought-out plan is essential to avoid compromising the hard work and preparation you’ve invested. While it’s true that ultra trail races rarely unfold exactly as anticipated, having a solid plan ensures you’re as prepared as possible for the challenges ahead.

For those seeking comprehensive guidance, including nutrition and personalized training plans, the RunMotion Coach app offers valuable resources. Monthly nutritional advice and specific recommendations tailored to the lead-up to your race are available to support your preparation fully.

Here’s to a successful and enjoyable race experience!

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Mailis Durif-VarambonMailis grew up in the mountains, where she went hiking and biking every weekend. She loves outdoor activities where she can relax at the end of the day. At RunMotion Coach, she is responsible for community management.