Trail nutrition: the complete guide to managing your energy in off-road running

Trail running is not prepared for in the same way as a classic 10k road race. The challenges are not the same: prolonged effort, repeated elevation changes, and digestion slowed down by impact.

Without an adapted nutritional strategy, you risk experiencing nausea, hypoglycemia, or a drop in performance.

In this guide, we will see how to adapt your trail running diet: before, during, and after the event to maintain your energy and limit digestive issues.

Why is nutrition different in trail running?

A longer and more irregular effort

Trail running differs from road running in its duration and variable intensity. Where a marathon lasts 3 to 5 hours at a stable pace, a trail run can extend from 2 hours to over 30 hours depending on the format and elevation. The pace constantly changes (ascents, descents, altitude, technical sections), forcing the body to exert an irregular effort. Your calorie needs therefore constantly fluctuate.

Specific constraints of trail running

On ascents, intensity increases and the body uses more carbohydrates as its primary energy source.

On descents, eccentric muscle contractions cause tissue micro-damage and progressive neuromuscular fatigue (Millet et al., 2011).

Environmental conditions also influence your needs: heat increases your water and electrolyte needs, while cold can decrease the sensation of thirst.

In trail running, gastrointestinal issues are quite common and can also complicate the ability to maintain sufficient nutritional intake (Costa et al., 2017).

Trail running nutrition: what to eat before the race?

The week leading up to the trail race

You should eat normally, with a varied and balanced diet during the first part of the week (D-7 to D-4).

From D-3 to D-1, it is advisable to:

• gradually consume more carbohydrates;
• reduce training volume.

Goal: maximize glycogen stores with 10 to 12 g of carbohydrates/kg/day to build up a good energy reserve before race day.

Prioritize easily digestible carbohydrate sources: white rice, white pasta, potatoes, compotes, ripe fruits. Supplement with lean proteins (chicken, turkey, fish, eggs) and healthy fats (olive or rapeseed oil, avocado, omega-3s).

The day before a trail race

The dinner the night before should be simple, easily digestible, and rich in carbohydrates. Leave no room for improvisation: this meal should consist of foods you have already tested.

Examples of classic menus:

1. white rice + steamed white fish + cooked zucchini + very ripe banana.
2. white pasta + grilled chicken + tender carrots + 1 fruit juice.

Avoid: strong spices, fatty dishes, and fiber.

Breakfast before the start

Before an endurance effort of more than 60 minutes, the ACSM recommends eating a meal containing 1 to 4 g of carbohydrates/kg, 1 to 4 hours before the start.

Breakfast is usually the pre-race meal.

It is very important, as it allows you to:

• start with readily available energy;
• limit the risk of a performance drop from the first kilometers.

Example of a trail breakfast:

1. white bread + jam;
2. porridge or rice pudding;
3. pancakes + honey + banana;
4. energy drink.

Add a small portion of protein if well tolerated.

If starting very early, opt for a light snack.

Example: compote + sports drink.

Nutrition during a trail race: the key to performance

How many carbohydrates per hour?

According to the work of researcher Asker Jeukendrup and the ACSM consensus:

• 1 to 2.5 hours: 30 to 45 g/h;
• 2.5 to 3.5 hours: 45 to 60 g/h;
• Beyond 3 hours: 60 to 90 g/h.

Going up to 90 g/h or even 120 g/h requires rigorous gut training, and you need to combine glucose/maltodextrin + fructose to optimize absorption.

Sweet, savory, or a mix of both?

Some trail runners find that after 4 to 5 hours of effort, energy gels become difficult to swallow. Sweet aversion is very common. Alternating sweet and savory (mini-sandwiches, cheese, chips, broth) helps avoid monotony.

Hydration and electrolytes

In trail running, hydration needs vary enormously depending on temperature, altitude, intensity, duration, and sweat rate. Stay within the range of 400 to 800 ml of water per hour depending on your needs.

Do not drink only plain water over long distances. Drink water containing minerals, especially sodium, to maintain fluid balance and prevent hyponatremia.

Adapting your diet according to distance

Short trail (20–30 km)

Over this distance, your glycogen reserves are largely sufficient. Nevertheless, plan for 30 to 40 g of carbohydrates per hour via gels, light bars, or an energy drink, taking into account your digestive tolerance.

Long trail (40–80 km)

Carbohydrate intake becomes strategic. Aim for up to 60 g per hour, varying formats: gels, bars, dried fruit, isotonic drinks. Incorporate savory items after 3 to 4 hours of effort.

Ultra-trail (80 km and +)

Nutrition for a trail of 80 km or more must be meticulously planned.

Aim for 60 to 90 g of carbohydrates per hour, with maximum variety: solid, semi-liquid, sweet, savory.

Incorporate solid foods at aid stations (pasta, rice, potatoes, soups).

Also plan for a moderate protein intake (5 to 10 g per hour).

Common mistakes in trail nutrition

Using new products on race day: always test your nutritional strategy during training to identify your level of digestive tolerance.

Drinking only water: without electrolytes, you risk hyponatremia over long distances.

Overloading the stomach: fragmenting intake limits digestive issues and optimizes absorption.

Neglecting hydration: even in cool weather, you sweat. Drink regularly in small quantities.

Example of a trail nutrition plan (practical case)

Strategy: 50 km trail (6-7 h)

• Fractionate intake every 15 to 20 min.
• Alternate sweet/savory after 3 h.
• Aim for ~60 g carbs/h and ~500 ml/h.

Important notes: This plan is a typical example. Adapt it to your level of digestive tolerance.

Post-trail nutrition: optimizing recovery

Metabolic window

The first few hours after the race are crucial. Quickly consume a snack that combines carbohydrates and proteins. This strategy is recommended by the International Society of Sports Nutrition (ISSN), which highlights its importance in the post-exercise recovery process.

Examples of post-trail snacks:

1. whey protein + maltodextrin + amino acids;
2. ham and cheese sandwich + banana;
3. Greek yogurt + honey + dried fruit;
4. fruit smoothie + milk + oats.

Follow with a complete meal within 2-3 hours.

Rehydrate gradually: 150% of lost weight (1 kg lost = 1.5 L).

Prefer water enriched with electrolytes, sodium-rich water.

FAQ – Trail Nutrition

What to eat before a 30 km trail run?

Have an easily digestible breakfast 1 to 4 hours before the start: porridge, white bread with jam, banana. Supplement with a gel 15 minutes before the start.

How much to drink during a trail run?

Aim for 400 to 800 ml per hour depending on the temperature and your sweating rate. Prefer a drink with electrolytes. Drink in small sips every 15 to 20 min.

Should you eat savory food during a trail run?

Yes, especially over long distances. Savory food provides sodium and reduces the feeling of being fed up with sweet tastes. Include broth, mini-sandwiches after 3-4 hours.

How to avoid digestive issues during a trail run?

Test your nutritional strategy multiple times. Divide food intake every 20 to 30 min. Avoid fiber, fats, and lactose. Hydrate regularly without excess.

What is the difference between marathon and trail nutrition?

Trail running often involves a longer effort time, irregular terrain, and variations in intensity. It requires more variety (sweet/savory), better electrolyte management, and adaptation to sometimes spaced-out aid stations.

In summary: what to remember

Trail nutrition is based on three pillars: anticipation, regularity, and personalization.

Optimize your glycogen stores beforehand, divide your carbohydrate intake during exercise (60 to 90 g/h), and compensate for your fluid and sodium losses.

Test your strategy during training. Vary the formats and flavors and take care of your recovery by consuming carbohydrates and protein after the finish line.

Disclaimer: The recommendations and advice in this guide are for informational purposes only. In case of illness (diabetes, chronic digestive problems, kidney problems), consult a health professional or a sports nutrition specialist.

Bibliography

Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Journal of the Academy of Nutrition and Dietetics, 116(3), 501–528. https://doi.org/10.1016/j.jand.2015.12.006

Jeukendrup A. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports medicine (Auckland, N.Z.), 44 Suppl 1(Suppl 1), S25–S33. https://doi.org/10.1007/s40279-014-0148-z

Kerksick, C. M., Arent, S., Schoenfeld, B. J., Stout, J. R., Campbell, B., Wilborn, C. D., Taylor, L., Kalman, D., Smith-Ryan, A. E., Kreider, R. B., Willoughby, D., Arciero, P. J., VanDusseldorp, T. A., Ormsbee, M. J., Wildman, R., Greenwood, M., Ziegenfuss, T. N., Aragon, A. A., & Antonio, J. (2017). International society of sports nutrition position stand: nutrient timing. Journal of the International Society of Sports Nutrition, 14, 33. https://doi.org/10.1186/s12970-017-0189-4

Urdampilleta, A., Arribalzaga, S., Viribay, A., Castañeda-Babarro, A., Seco-Calvo, J., & Mielgo-Ayuso, J. (2020). Effects of 120 vs. 60 and 90 g/h carbohydrate intake during a trail marathon on neuromuscular function and high intensity run capacity recovery. Nutrients, 12(7), 2094. https://doi.org/10.3390/nu12072094

Millet, G. Y., Tomazin, K., Verges, S., Vincent, C., Bonnefoy, R., Boisson, R.-C., Gergelé, L., Féasson, L., & Martin, V. (2011). Neuromuscular consequences of an extreme mountain ultra-marathon. PLoS ONE, 6(2), e17059. https://doi.org/10.1371/journal.pone.0017059

Costa, R. J. S., Snipe, R. M. J., Kitic, C. M., & Gibson, P. R. (2017). Systematic review: Exercise-induced gastrointestinal syndrome—implications for health and intestinal disease. Alimentary Pharmacology & Therapeutics, 46(3), 246–265. https://doi.org/10.1111/apt.14157