Training your gut is just as important as training your legs.

If you’ve ever struggled with stomach cramps, bloating, or nausea during a long run, cycle or race, you’re not alone. These are signs that your gut isn’t ready to handle the fuel you're giving it.

But here’s the good news. Just like your muscles adapt to training, your gut can too.

“Gut training” is the process of gradually teaching your digestive system to tolerate carbohydrates and fluids during exercise—without discomfort.

It helps improve fuel delivery, reduces the risk of GI distress, and allows you to race and train at a higher intensity for longer.

In this post, you’ll learn:

• Why gut training matters

• How your gut adapts

• Simple strategies to start training your gut

• Common mistakes to avoid

Whether you’re prepping for a marathon or just want to perform better on long sessions, training your gut can be a game-changer.

An overview of gut training strategies

Training your gut is about gradually exposing your digestive system to the same nutrition strategy you’ll use on race day.

Here’s how it works:

Key strategies to include in training:

• Drink larger volumes of fluid during sessions to improve stomach tolerance

• Train soon after eating to challenge digestion under stress

• Consume carbohydrates during longer runs to mimic race fueling

• Simulate your race-day nutrition. Try to match your planned carb and fluid intake

What happens over time:

• Gastric emptying improves, meaning food and fluids move through your stomach faster

• Absorption capacity increases, allowing you to take in more carbs with fewer issues

• You experience less bloating, nausea, and GI discomfort during hard efforts

The result?

• Less GI stress

• Better fuel availability

• Improved performance on race day

When to start gut training

Timing matters. Gut training shouldn’t be an afterthought in the final weeks before your event.

Here’s a simple timeline:

• Preparation phase (6-12 weeks out):
  Focus on building aerobic capacity, technique, and base mileage. Start gut training early if possible—especially during key long sessions.

• Performance phase (6-8 weeks out):
  This is when intensity increases and race-specific sessions begin.
  At the very latest, begin replicating your race-day nutrition here.

Your gut needs multiple exposures to adapt. Waiting until race week doesn’t give your body enough time to adjust, and that increases your risk of GI issues. The more carbs you plan to consume during the race (for example, 90g+ per hour), the earlier you should start this in your training block.

Takeaway

Plan your gut training just like your run sessions. The earlier you start, the more confident you’ll feel on race day.

Why do gut issues occur?

Most exercise-related gut issues happen because of -

• Reduced gastric emptying
• Malabsorption of water and nutrients
• Delayed transit time

Plus there is a shift in blood flow away from the gut during exercise. Gastric emptying rate is impeded by high-intensity exercise and further slowed by dehydration and hyperthermia. (Reference, Reference)

Why stress management is crucial

Not managing stress in the build-up to a race and on race day itself can play havoc with your gut.

How to manage stress is well beyond this post but try to employ techniques to lower stress levels leading into the race. 

Pre-race nerves play a huge role in this.

Key points to help:

• Plan your race day strategy and test this in training so you know it.
• Plan your travel / kit etc
• Have extras of everything in case you lose something or it breaks
• Know where aid stations are and what products are on them
• Carb load properly so you are not chasing your nutrition the night before / morning of the race.

Supplements to use for gut training

While dietary strategies and progressive exposure to race-day fueling form the foundation of gut training, certain supplements can support gut health and reduce the risk of GI distress, especially in the final build-up to race day.

 

Key takeaways

Gut training isn’t just about avoiding discomfort. It’s about creating a system that can efficiently absorb and utilise the fuel you need to perform at your best. 

Start early. Be consistent. Treat your gut like a muscle, it gets stronger with use.

With the right strategy and smart support, you’ll not only reduce GI stress, you’ll unlock better energy delivery and race-day performance.

Links to the products above are here - 

Glutamine - buy here
Electrolytes - buy here