Trail Running Nutrition: Health Impact & Optimal Dosing

Sports Nutrition in Trail Running: What It Really Does to Your Health

Sports nutrition and health in trail running

You open a gel at mile 18.

And someone tells you: "You're going to ruin your teeth."

Meanwhile, endurance recommendations climb to 90, sometimes 120 g/h.

Two opposing narratives.

The good news: physiology weighs in, and it's usable on your next long run.

On the Agenda

  • 3 essential insights
  • 2 inspirations
  • 1 scientific explanation
  • Key takeaways
Impact of sports nutrition on health

3 Essential Insights on Sports Nutrition

1. Your Body Processes Sugar Differently When You Run

During exercise, muscles take up glucose via a pathway that functions even without insulin. Sugar goes directly where energy is lacking: maximum muscle sensitivity, stable blood sugar, immediate glycogen replenishment.

👉 Sports nutrition is designed for sustained effort. Keep it for this context.

2. Your Optimal Dose Is What Your Gut Absorbs

The 120 g/h you see on Instagram comes from athletes who maintain very high intensities and have been training their digestion for seasons.

  • 60 g/h: well-absorbed with glucose alone
  • 90 g/h: achievable with glucose + fructose (2:1 ratio)
  • Beyond: experimental territory

👉 Increase in increments of 10 g/h over several weeks, paying attention to your digestion.

3. Your Daily Diet Has the Biggest Impact

Your race products account for 3 to 6 hours out of 168. The rest — meals, sleep, stress — builds your metabolic health.

For your teeth: rinse with plain water after consuming sugar, wait 30 minutes before brushing.

👉 Prioritize your daily diet, and sports nutrition becomes a simple performance tool.

Carbohydrate dosing trail running

2 Inspirations

Scientific studies sports nutrition

Scientific Insight: Exercise-Induced Gastrointestinal Syndrome

The review by Costa et al. (2017) describes exercise-induced gastrointestinal syndrome: during prolonged exertion, blood is diverted to the muscles, the gut receives less, and absorption deteriorates. Heat, dehydration, intensity, and duration worsen the picture. Result: nausea, bloating, inability to eat late in a race.

Jeukendrup (2014) provides the solution: intestinal transporters for glucose and fructose multiply when regularly stimulated. An athlete who trains their gut absorbs more, with fewer symptoms.

👉 Gut training develops like your endurance or strength.

References: Costa et al., 2017 · Jeukendrup, 2014

Gut training protocol trail

Protocol: Train Your Gut in 6 Weeks

This progressive protocol helps you optimize your carbohydrate absorption during exercise:

  • Weeks 1-2: 40-50 g/h on a long run. Rate your comfort out of 10.
  • Weeks 3-4: 60-70 g/h, with a glucose + fructose product.
  • Weeks 5-6: 80-90 g/h, using the exact format of your race.
  • Always: 400 to 600 ml/h — water is crucial for absorption.

Example 80 g/h: 1 gel at 25g every 45 min + 500 ml of drink at 40g/L per hour.

If symptoms persist despite gentle progression, a sports nutritionist can help you individualize your plan.

Key Takeaways

  • Carbohydrates consumed during exercise use a specific metabolic pathway.
  • Your true limit is your intestinal absorption capacity.
  • A glucose + fructose mix allows you to exceed 60 g/h.
  • Your digestive tolerance can be improved incrementally.
  • Your long-term health depends on your daily meals.

The best nutrition plan is the one you can stick to for years without thinking. Test it out now.

— Antoine, Baptiste, and Etienne from TRL