Trail running requires much more than cardiovascular endurance. Uneven terrain, elevation gain, long race durations, and constant changes in intensity significantly increase energy demands, making a well-planned supplementation strategy essential for maintaining performance all the way to the finish line.
Unlike road running, trail races often alternate between high-intensity uphill sections and lower-intensity downhill segments, requiring a steady supply of energy and an effective hydration strategy.
Energy demands are different in trail running
Trail races are often longer and less predictable. In addition to distance, factors such as elevation, temperature, terrain, and total exercise duration directly influence energy expenditure.
Long climbs increase muscle recruitment and carbohydrate utilization, while technical descents place greater eccentric stress on the muscles, contributing to fatigue as the race progresses.
For this reason, starting the race with adequate glycogen stores and maintaining carbohydrate intake throughout the event are key to sustaining performance.
How much carbohydrate should you consume during the race?
Current recommendations suggest consuming between 30 and 90 g of carbohydrates per hour, depending on race duration, exercise intensity, and the athlete's level of gut training.
During events lasting more than 2.5 hours, strategies providing up to 90 g of carbohydrates per hour may help maintain exercise intensity and delay fatigue, especially when multiple transportable carbohydrates, such as glucose and fructose, are consumed.
In addition to the total amount, spreading carbohydrate intake consistently throughout the race is generally more effective than waiting until energy levels begin to decline.
Hydration deserves special attention
Hydration can be particularly challenging in trail running due to environmental conditions and the limited availability of aid stations.
Fluid and sodium losses vary considerably between athletes, and replacing water alone is not always sufficient. During long races or competitions held in hot environments, electrolyte replacement helps maintain fluid balance, supports fluid absorption, and reduces the risk of dehydration and exercise-associated hyponatremia.
Ideally, athletes should know their sweat rate and adjust both fluid and sodium intake according to the specific demands of the race.
How should you organize your supplementation strategy?
A simple and well-structured plan makes race-day nutrition easier to execute.
About 10 to 15 minutes before the start, consuming a carbohydrate gel can help increase carbohydrate availability at the beginning of the race.
During the event, regular intake of carbohydrate gels or carbohydrate-containing sports drinks helps maintain a continuous supply of energy. For longer races, easily digestible solid foods may also be included, depending on individual gastrointestinal tolerance.
When appropriate, caffeine-containing products may be strategically used during the second half of the race or before demanding climbs, always considering the athlete's individual tolerance and overall nutrition plan.
Practice your nutrition strategy during training
A supplementation strategy should never be tested for the first time on race day.
Long training sessions provide the ideal opportunity to determine carbohydrate intake, establish feeding frequency, evaluate gastrointestinal tolerance, and identify which products work best for each athlete.
This process, known as gut training, improves the body's ability to absorb carbohydrates while reducing the likelihood of gastrointestinal discomfort during endurance events.
Conclusion
In trail running, supplementation involves much more than taking a gel when fatigue appears. A well-planned strategy that includes carbohydrates, hydration, electrolytes, and, when appropriate, caffeine helps maintain energy availability throughout the race and minimizes performance decline. Testing this strategy during training is essential for arriving at race day with confidence and a predictable nutrition plan.
