Nutrition - Fuelling for Race Day

Testing your kit and pacing in training is standard practice - so why ignore your nutrition?

When it comes to race-day fuel intake, there’s good reason to treat your gut like a muscle and train it under pressure.

Why delivering the right fuel on race day isn’t luck, but science.

Designing the Experiment

A true experimental approach sets up clear conditions:

1. Participants – A diverse group of triathletes (e.g., aged 18–45, mixed genders, and triathlon experience).

2. Intervention – A structured “gut-training” protocol during key sessions (e.g., long rides or bricks over 6–8 weeks).

3. Control – A group sticking to basic hydration or placebo feeds.

4. Measurements – Energy intake logs, gastrointestinal symptoms (Ex-GIS), digestion markers, and perceived effort or performance metrics.

   
   

Results from the literature show that repeated carbohydrate intake at race-day levels (60–90 g/h), during training, leads to:

• ~47%–54% reduction in gut discomfort and malabsorption.

• Maintenance or enhancement of carbohydrate absorption capacity.

• Reduced gastrointestinal symptoms (especially stomach upset or bloating).

  
  

These findings are backed by repeatable experimental trials: one study observed a 45–54 % drop in malabsorption after 2 weeks of gut training.

Practical Application: Your Race‑Day Nutrition “Trial Runs”

1. Simulate Gastro Conditions

Choose 1–2 key sessions per week (a long ride or a brick) to practice your planned fuel intake. Match the amount (e.g., 60–90 g carbs per hour) and form (gels, bars, drink) you'd use on race day.

2. Monitor and Adjust

Record how you feel — bloating? Energy? Digestive comfort? Track symptoms and energy levels to spot patterns and tweak intake as needed.

3. Vary the Conditions

Train in weather and durations similar to your target race. Train the gut under heat or for long durations, reflecting real-race stresses.

4. Repeat and Progress

Consistency matters. Like strengthening muscles, your gut adapts over weeks — commit 4–8 weeks and fuel every key long effort.

Ironman Portugal - Cascais

What You Can Expect

• Better tolerance for race-day volumes, fewer hunger or nausea episodes.

• More reliable energy – fewer spikes/dips, more sustained effort.

• Confidence at nutrition aid stations – knowing what works removes guesswork.

Coach’s Tip: Think of race-day nutrition as dress rehearsals: wear your kit, rehearse race-day nutrition, and simulate effort. Use tools like timers or watch cues to help you stick to your intake plan - don’t wait until you're craving fuel, by then it's often too late. By using a research-informed, repeatable approach - including control conditions, systematic tracking, and progressive adaptation - you turn nutrition from a wildcard into a performance weapon.

Train your gut. Train smart. Race stronger.