Ultra-Trail Nutrition: Building a Resilient Digestive System

Ultra-Trail Nutrition: Building a Digestive System That Lasts

Ultra-trail nutrition: digestive system and hydration

Ultra-trail running is a lifestyle: mental load, sleep, stress, a delicate digestive system, your tribe, your identity… and amidst all this, a very concrete challenge: being able to absorb what you consume.

Because in ultras, the limit often comes from the gut. Your legs, cardio, and mind might be able to keep going, but if your digestive system goes on strike, the race becomes a constant negotiation. Hydration, assimilation, a stable protocol: performance starts in the digestive system.

The Digestive System: The True Final Boss of Ultra

In ultra-trail running, the real adversary isn't always the elevation gain or the distance. It's often the digestive system. When the gut gives up, physical condition no longer matters: the race becomes a torment.

The nutritional goal in ultra is to maintain a stable energy curve, avoiding glycemic rollercoasters that exhaust the body. To do this, several strategies are essential:

  • Prioritize progressively absorbed carbohydrate sources (maltodextrin, fructose)
  • Incorporate electrolytes to support intestinal function
  • Prepare the digestive "terrain" beforehand with prebiotics and postbiotics
  • Use natural and well-tolerated ingredients (sea salt, vitamins)

The modern approach to ultra-nutrition relies on a combination of prebiotics + postbiotics, which combines a long-term effect (strengthening the intestinal flora) and a rapid effect (immediate support of the intestinal barrier). This dual action helps prepare the digestive system to withstand prolonged effort.

Nutritional strategy for ultra-trail

Hydration: A Fragile Balance Between Too Little and Too Much

In ultra-trail, simply “drinking water” is not enough. You need to find a fluid + electrolyte balance adapted to the intensity, duration, and climatic conditions.

Too little hydration leads to decreased performance, concentration issues, and an increase in core body temperature. Too much hydration (especially without electrolytes) can cause hyponatremia, which is potentially dangerous.

Hydration Strategy According to Conditions

Hydration must be proactive and strategic, adapted to the following parameters:

  • Cool temperatures (<20°C): moderate hydration, fractional dose per hour
  • Moderate temperatures (20-30°C): regular hydration with electrolytes
  • High temperatures (>30°C) or heavy sweating: up to 1 full dose of electrolytes per hour, with a significant intake of sodium (1380 mg or more depending on individual needs)

The benefit of electrolytes, particularly sodium, is to support fluid balance, especially when sensations are distorted by fatigue, heat, or stress. In ultra, hydration is not a "by feel" reflex that you activate when it's too late: it's a discipline to plan.

Modern Nutritional Protocol: Simplicity and Regularity

Modern ultra-running relies on a principle: regular fueling + tolerance + simplicity. Rather than multiplying formats and sources, the idea is to build a protocol that coherently meets the needs of prolonged effort.

The Pillars of an Effective Ultra Protocol

  • Energy drink (DrinkMix): neutral-tasting carbohydrate blend, designed to avoid taste fatigue over long durations
  • Concentrated gel: an "all-in-one" flask format combining carbohydrates, electrolytes, and vitamins, with dilution recommendations to facilitate assimilation
  • Electrolyte hydration: dedicated powder to maintain fluid balance without overloading the digestive system
  • Intestinal support: specific supplement for digestive "terrain," to be taken daily in preparation

The goal is to build a stable protocol that you can maintain even when you're tired, even when sensations become muddled, even when every action requires mental effort.

Nutrition products for ultra-endurance

What Science Says About Ultra Nutrition

Two major scientific points guide nutritional strategy in ultra-endurance:

The Gut Suffers During Prolonged Effort

Ultra-effort leads to a decrease in digestive blood flow. Blood is preferentially redirected to the muscles, heart, and lungs, leaving the intestines under-perfused. This intestinal ischemia significantly increases the risk of gastrointestinal issues during long efforts.

Research (notably Hoogervorst et al., MDPI Sports) shows that preparing the digestive system, through an adapted nutritional strategy and training digestive tolerance, can significantly reduce these issues.

Hydration Must Be Anticipated

Armstrong's work (2021, Nutrients) confirms that hydration must be proactive. Waiting for the sensation of thirst or the first signs of dehydration is too late in ultra. The benefit of electrolytes, particularly sodium, is to maintain fluid balance even when natural regulatory mechanisms are disrupted by prolonged effort.

In ultra, nutrition is a discipline in itself. A simple, repeatable, and tested strategy is better than a perfect… but never-followed strategy.

Ultra-trail nutritional protocol

Putting It Into Practice: Building Your Nutritional Protocol

Here's a structured approach to building a solid nutritional protocol for ultra-trail:

Daily (Foundation Block)

Prepare the digestive "terrain" beforehand with a stable routine. The goal is to strengthen intestinal health long-term, via a course of prebiotics and postbiotics during the weeks leading up to your goal race.

During Effort (Hydration Block)

Incorporate electrolytes adapted to the conditions (temperature, sweating) rather than simply drinking water. Plan intake according to a regular schedule, without waiting for the sensation of thirst.

During Effort (Energy Block)

Choose an energetic guiding principle: either a DrinkMix type beverage or an "all-in-one" concentrated gel. Adjust tolerance by fractioning or diluting if necessary, especially early in the race when the gut is still vulnerable.

Golden Rule: Test Everything In Training

All elements of the nutritional and hydration protocol must be tested in training, under specific conditions:

  • Long sessions to evaluate digestive tolerance over time
  • Training in heat to validate the hydration protocol
  • Technical descents to measure the impact of jostling on the digestive system
  • Variable intensity sessions to observe reactions according to effort

Never discover a product, format, or strategy on race day. Ultra is also won in nutritional preparation.

Tested nutritional strategy for ultra-trail

Building a System That Lasts

In ultra-trail, nutrition is not a secondary variable. It's a system to build, test, and adjust. The gut is the critical link: if you neglect it, it will make you pay precisely when you most need your resources.

The winning approach combines:

  • Daily digestive preparation
  • Proactive hydration with electrolytes
  • Regular and well-tolerated energy intake
  • Repeated tests in training under varied conditions

Simplicity and repeatability are better than theoretical perfection. Test in training. Adjust. Stabilize. Then take your protocol far, very far.

— Antoine, Baptiste, and Etienne from TRL