Trail running and ultra running are among the most demanding endurance sports. Prolonged effort, elevation gain, changing pace and challenging terrain mean that the right nutrition and supplementation strategy is just as important as the training itself.
In practice, many athletes prepare their physical fitness but fail to prepare their bodies to receive energy consistently during exercise. Yet nutrition during trail runs often determines whether you can maintain your pace, recover effectively and finish the race without an energy crisis.
During a run lasting several hours, the body gradually uses up:
If these are not replenished regularly, the result can be:
That is why a trail running nutrition strategy is one of the most important performance factors in endurance racing.
How do you prepare your body for a trail race?
Preparing for a trail race involves more than running training. It also requires metabolic and nutritional adaptation.
Key elements of preparation include:
-
developing aerobic fitness,
-
uphill and downhill training,
-
improving running economy,
-
adapting the muscles to eccentric loading,
-
gut training.
Regular training sessions with carbohydrate intake improve gastrointestinal tolerance and increase the body’s ability to use energy during exercise.
In practice, you can train your gastrointestinal tract much like you train your muscles.
Pre-race nutrition – how to build up your energy stores
24–48 hours before the race
In the days leading up to the race, the aim is to maximise muscle glycogen stores and ensure adequate hydration.
Recommendations:
-
6–10 g of carbohydrates/kg of body weight/day,
-
regular fluid intake,
-
increasing sodium intake,
-
limiting excess fibre and hard-to-digest foods.
The best options include:
-
rice,
-
pasta,
-
bread,
-
pancakes,
-
fruit,
-
isotonic drinks.
What should you eat before a trail run?
Your pre-race meal should provide readily available energy without placing excessive strain on the gastrointestinal tract.
3–4 hours before the start:
-
1–3 g of carbohydrates/kg of body weight,
-
a moderate amount of protein,
-
low amounts of fat and fibre.
Example meals:
-
rice with banana and honey,
-
oatmeal with fruit,
-
pancakes with maple syrup,
-
white bread rolls with jam.
Nutrition during a trail run
During prolonged exercise, a consistent energy intake becomes one of the most important factors in maintaining performance.
That is why the answer to the question:
“how many carbohydrates per hour during a trail run?”
is so important for athletes taking part in mountain and ultra races.
How many carbohydrates per hour during trail running?
Current sports nutrition recommendations indicate:
1–2-hour races
2–3-hour races
Trail and ultra >3 hours
For advanced athletes, intake can reach:
However, this requires a well-trained gastrointestinal tract and regular gut training.
Research shows that such a high carbohydrate intake may help maintain pace and delay the build-up of fatigue during prolonged exercise. Without prior gut adaptation, high CHO doses may increase the risk of gastrointestinal problems.
Why does combining glucose and fructose work better?
During exercise, the body uses different intestinal transporters:
-
glucose → SGLT1,
-
fructose → GLUT5.
Each of these systems has limited capacity, so relying on a single carbohydrate source quickly leads to saturation.
Combining glucose and fructose allows two independent absorption pathways to be used, increasing the total amount of energy delivered during exercise.
The most commonly used ratios are:
Benefits:
-
greater energy availability,
-
better gut tolerance,
-
the ability to maintain an intake of 60–90 g CHO/h,
-
more stable energy levels during prolonged exercise.
That is why glucose-fructose blends are now standard in modern trail running and ultra-endurance nutrition.
What should you eat during a trail run?
The most commonly used products include:
-
energy gels,
-
isotonic drinks,
-
gummies and chews,
-
bananas,
-
dates,
-
fruit purées,
-
rice cakes,
-
soft energy bars.
In ultra trail races, many athletes also use “real food” products to reduce flavour fatigue from sweet products.
The most important thing, however, is to test your nutrition strategy in training beforehand.
Hydration during an ultra – how much should you drink and how much sodium do you need?
Hydration during an ultra should include not only fluids but also electrolytes, especially sodium.
Recommendations:
-
400–800 ml of fluids/h,
-
300–600 mg of sodium/h.
Your exact requirements depend on:
-
temperature,
-
exercise intensity,
-
sweat rate,
-
race duration.
In practice, the most useful options include:
Supplementation strategy for trail running
During long races, the right supplementation strategy can have a significant impact on maintaining performance and limiting fatigue.
The most important elements are:
The longer the race, the more important an effective supplementation strategy becomes.
In practice, it is fair to say that during an ultra trail race, more than half of success depends on effective energy and hydration management.
Gut training – preparing your gut for an ultra
Gut training is now one of the most important elements of preparing for ultra races.
Regular carbohydrate intake during training improves:
-
gel tolerance,
-
glucose and fructose absorption,
-
the rate of gastric emptying,
-
comfort during exercise.
In practice, it is worth regularly training with:
The most common nutrition mistakes during trail races
The most common mistakes athletes make include:
-
insufficient carbohydrate intake,
-
not taking electrolytes,
-
eating inconsistently,
-
starting to fuel too late,
-
not training the gut,
-
testing new products during a race.
Even a well-prepared athlete can lose significant pace because of nutrition mistakes.
FAQ – nutrition for trail running
How many gels per hour during a trail run?
Usually 1–3 gels/h, depending on total carbohydrate intake.
Do you need to supplement sodium during a trail race?
Yes, especially during long races and in high temperatures.
How do you train your gut before an ultra?
Gradually increase your CHO intake during training.
What should you eat at aid stations?
Gels, isotonic drinks, bananas, fruit purée and savoury foods.
Can you run an ultra on a low-carb diet?
Yes, although most athletes still use a high carbohydrate intake during races.
Summary
Modern trail running nutrition includes:
-
adequate carbohydrate intake,
-
hydration and electrolytes,
-
gut training,
-
an individual supplementation strategy,
-
consistent energy intake during exercise.
In practice, the result is determined not only by fitness but above all by your ability to manage energy throughout the race.
References
Podlogar T, Wallis GA. New Horizons in Carbohydrate Research for Endurance Athletes. Sports Medicine, 2022.
Costa RJS et al. Exercise-Induced Gastrointestinal Syndrome. Sports Medicine, 2023.
Wallis GA, Podlogar T. Dietary Carbohydrate and Endurance Performance. GSSI Sports Science Exchange, 2022.
Cao W et al. Carbohydrate Supplementation Strategies in Endurance Sports. Nutrients, 2025.
Jeukendrup AE. Carbohydrate Intake During Exercise and Performance. Nutrition, 2004.
Tiller NB et al. ISSN Position Stand: Nutritional Considerations for Ultra-Marathon Training and Racing. JISSN, 2019.
IOC Consensus Statement on Sports Nutrition, 2018.
Nutrition and supplementation for trail running – how to prepare your body for a race and what to eat during the event
Trail running and ultra running are among the most demanding endurance sports. Prolonged effort, elevation gain, changing pace and challenging terrain mean that the right nutrition and supplementation strategy is just as important as the training itself.
In practice, many athletes prepare their physical fitness but fail to prepare their bodies to receive energy consistently during exercise. Yet nutrition during trail runs often determines whether you can maintain your pace, recover effectively and finish the race without an energy crisis.
During a run lasting several hours, the body gradually uses up:
muscle glycogen,
fluids,
sodium and electrolytes,
energy stores needed for muscle and nervous system function.
If these are not replenished regularly, the result can be:
a drop in pace,
increasing fatigue,
gastrointestinal problems,
reduced concentration,
the so-called “bonk”.
That is why a trail running nutrition strategy is one of the most important performance factors in endurance racing.
How do you prepare your body for a trail race?
Preparing for a trail race involves more than running training. It also requires metabolic and nutritional adaptation.
Key elements of preparation include:
developing aerobic fitness,
uphill and downhill training,
improving running economy,
adapting the muscles to eccentric loading,
gut training.
Regular training sessions with carbohydrate intake improve gastrointestinal tolerance and increase the body’s ability to use energy during exercise.
In practice, you can train your gastrointestinal tract much like you train your muscles.
Pre-race nutrition – how to build up your energy stores
24–48 hours before the race
In the days leading up to the race, the aim is to maximise muscle glycogen stores and ensure adequate hydration.
Recommendations:
6–10 g of carbohydrates/kg of body weight/day,
regular fluid intake,
increasing sodium intake,
limiting excess fibre and hard-to-digest foods.
The best options include:
rice,
pasta,
bread,
pancakes,
fruit,
isotonic drinks.
What should you eat before a trail run?
Your pre-race meal should provide readily available energy without placing excessive strain on the gastrointestinal tract.
3–4 hours before the start:
1–3 g of carbohydrates/kg of body weight,
a moderate amount of protein,
low amounts of fat and fibre.
Example meals:
rice with banana and honey,
oatmeal with fruit,
pancakes with maple syrup,
white bread rolls with jam.
Nutrition during a trail run
During prolonged exercise, a consistent energy intake becomes one of the most important factors in maintaining performance.
That is why the answer to the question:
“how many carbohydrates per hour during a trail run?”
is so important for athletes taking part in mountain and ultra races.
How many carbohydrates per hour during trail running?
Current sports nutrition recommendations indicate:
1–2-hour races
30–45 g CHO/h
2–3-hour races
45–60 g CHO/h
Trail and ultra >3 hours
60–90 g CHO/h
For advanced athletes, intake can reach:
90–120 g CHO/h.
However, this requires a well-trained gastrointestinal tract and regular gut training.
Research shows that such a high carbohydrate intake may help maintain pace and delay the build-up of fatigue during prolonged exercise. Without prior gut adaptation, high CHO doses may increase the risk of gastrointestinal problems.
Why does combining glucose and fructose work better?
During exercise, the body uses different intestinal transporters:
glucose → SGLT1,
fructose → GLUT5.
Each of these systems has limited capacity, so relying on a single carbohydrate source quickly leads to saturation.
Combining glucose and fructose allows two independent absorption pathways to be used, increasing the total amount of energy delivered during exercise.
The most commonly used ratios are:
2:1,
1:0.8,
1:1.
Benefits:
greater energy availability,
better gut tolerance,
the ability to maintain an intake of 60–90 g CHO/h,
more stable energy levels during prolonged exercise.
That is why glucose-fructose blends are now standard in modern trail running and ultra-endurance nutrition.
What should you eat during a trail run?
The most commonly used products include:
energy gels,
isotonic drinks,
gummies and chews,
bananas,
dates,
fruit purées,
rice cakes,
soft energy bars.
In ultra trail races, many athletes also use “real food” products to reduce flavour fatigue from sweet products.
The most important thing, however, is to test your nutrition strategy in training beforehand.
Hydration during an ultra – how much should you drink and how much sodium do you need?
Hydration during an ultra should include not only fluids but also electrolytes, especially sodium.
Recommendations:
400–800 ml of fluids/h,
300–600 mg of sodium/h.
Your exact requirements depend on:
temperature,
exercise intensity,
sweat rate,
race duration.
In practice, the most useful options include:
isotonic drinks,
electrolytes,
soft flasks with carbohydrates,
sodium capsules.
Supplementation strategy for trail running
During long races, the right supplementation strategy can have a significant impact on maintaining performance and limiting fatigue.
The most important elements are:
carbohydrates,
electrolytes,
caffeine,
carbohydrate drinks,
products that support hydration.
The longer the race, the more important an effective supplementation strategy becomes.
In practice, it is fair to say that during an ultra trail race, more than half of success depends on effective energy and hydration management.
Gut training – preparing your gut for an ultra
Gut training is now one of the most important elements of preparing for ultra races.
Regular carbohydrate intake during training improves:
gel tolerance,
glucose and fructose absorption,
the rate of gastric emptying,
comfort during exercise.
In practice, it is worth regularly training with:
30–90 g CHO/h,
different forms of energy intake,
your race nutrition strategy.
The most common nutrition mistakes during trail races
The most common mistakes athletes make include:
insufficient carbohydrate intake,
not taking electrolytes,
eating inconsistently,
starting to fuel too late,
not training the gut,
testing new products during a race.
Even a well-prepared athlete can lose significant pace because of nutrition mistakes.
FAQ – nutrition for trail running
How many gels per hour during a trail run?
Usually 1–3 gels/h, depending on total carbohydrate intake.
Do you need to supplement sodium during a trail race?
Yes, especially during long races and in high temperatures.
How do you train your gut before an ultra?
Gradually increase your CHO intake during training.
What should you eat at aid stations?
Gels, isotonic drinks, bananas, fruit purée and savoury foods.
Can you run an ultra on a low-carb diet?
Yes, although most athletes still use a high carbohydrate intake during races.
Summary
Modern trail running nutrition includes:
adequate carbohydrate intake,
hydration and electrolytes,
gut training,
an individual supplementation strategy,
consistent energy intake during exercise.
In practice, the result is determined not only by fitness but above all by your ability to manage energy throughout the race.
References
Podlogar T, Wallis GA. New Horizons in Carbohydrate Research for Endurance Athletes. Sports Medicine, 2022.
Costa RJS et al. Exercise-Induced Gastrointestinal Syndrome. Sports Medicine, 2023.
Wallis GA, Podlogar T. Dietary Carbohydrate and Endurance Performance. GSSI Sports Science Exchange, 2022.
Cao W et al. Carbohydrate Supplementation Strategies in Endurance Sports. Nutrients, 2025.
Jeukendrup AE. Carbohydrate Intake During Exercise and Performance. Nutrition, 2004.
Tiller NB et al. ISSN Position Stand: Nutritional Considerations for Ultra-Marathon Training and Racing. JISSN, 2019.
IOC Consensus Statement on Sports Nutrition, 2018.