Hello Runner,
Welcome back to your weekly moment of endurance nutrition!
Happy Weekend!
How was your week?
My week was good.
I trained hard, but I also felt a lot of muscle pain. I slowed down my running pace because my legs felt very heavy.
At work, I did a lot of what I was supposed to do and created a lot of content.
There are only 15 days left until I run my first half-marathon, and I confess that I'm already anxious. I feel butterflies in my stomach, but I think everything will be fine.
I already know which energy gel I'm going to take, what clothes I'm going to wear... in short, everything is practically decided.
In today's email, I want to talk about the topic of irritable bowel syndrome and why it can interfere with running performance. Many runners do not know what this means, and many may suffer from this syndrome. Let’s delve deeper.
Running is often described as a freeing, energizing practice. But for many runners, training comes with an uncomfortable and frustrating side effect: abdominal pain, bloating, gas, or the sudden need to find a bathroom mid-run.
These symptoms are often brushed off as “normal runner issues,” nerves, or something that will eventually go away. In reality, for some athletes, they may be signs of irritable bowel syndrome (IBS)—a common digestive condition that can significantly affect training quality, confidence, and performance.
IBS is manageable. With the right guidance and strategies, runners can reduce symptoms, protect gut health, and return to consistent, enjoyable training.
What is irritable bowel syndrome (IBS)?
IBS is a functional gastrointestinal disorder (affecting 10-15% of the population). This means the gut looks normal on medical tests, but it doesn’t function normally.
IBS affects how the intestines move and how sensitive they are to food, stress, and physical activity. It is not dangerous, but it can be disruptive, especially for endurance athletes like runners.
IBS is unique to each sufferer, but often there are shared characteristics. IBS can be categorized into different types based on the predominant symptoms:
IBS-D (diarrhoea-predominant): Individuals with IBS-D experience frequent episodes of diarrhoea. This can be accompanied by urgency and a constant need to use the toilet
IBS-C (constipation-predominant): IBS-C is characterized by infrequent bowel movements and hard, lumpy stools. People with this type often struggle with abdominal discomfort and a feeling of incomplete evacuation
IBS-M (mixed-type): Some individuals may experience a mix of both diarrhoea and constipation, with their symptoms varying over time
IBS-U (unsubtyped): This category is used when the symptoms do not clearly fit into any of the above types
How can IBS interfere with running?
Running places unique demands on the digestive system. During exercise, blood flow is redirected away from the gut toward working muscles, and the repetitive impact of running can stimulate bowel movements.
For runners with IBS, this can lead to:
Increased gut sensitivity during training
Faster intestinal movement (or sometimes delayed movement)
Heightened response to certain foods or stress
The result is often unpredictable symptoms, which can:
Disrupt long runs and workouts
Create anxiety around training or races
Reduce fueling confidence
Affect recovery and consistency
Common signs and symptoms runners often ignore
Runners with IBS may experience:
Abdominal pain or cramping (especially before or during runs)
Bloating or excessive gas
Urgent need to use the bathroom during training
Diarrhea, constipation, or alternating between both
Symptoms that worsen with stress or hard sessions
Relief of pain after a bowel movement
If these symptoms happen repeatedly and interfere with training, they are not something to ignore.
What to do if a runner suspects IBS
If a runner suspects IBS, the first step is not self-diagnosis or eliminating foods randomly.
1. Seek a proper diagnosis
A runner should consult a gastroenterologist or primary care physician to:
Rule out conditions like celiac disease, inflammatory bowel disease, or food intolerances
Confirm whether symptoms align with IBS
2. Work with a qualified nutrition professional
A sports dietitian or nutritionist with gut health experience can:
Identify personal symptom triggers
Recommend a Low FODMAP diet
Adjust fueling strategies without harming performance
Support gut health while maintaining adequate energy intake
This combination is key: medical evaluation + individualized nutrition guidance.
PRACTICAL SOLUTIONS
Supportive First Steps
Here are supportive first steps, not quick fixes or long-term treatment plans.
1. Review pre-run fueling timing
Eating too close to a run can trigger symptoms. Many runners benefit from:
Allowing 2–3 hours between larger meals and running
Choosing easily digestible foods before training
2. Simplify pre-run food choices
Highly fatty, very spicy, or large mixed meals may worsen symptoms.
Opt for simple carbohydrates
Keep protein and fat very moderate before runs
3. Stay consistent with hydration
Dehydration can worsen both constipation and diarrhea.
Drink fluids consistently throughout the day, not just before running
Keep a reusable bottle of water close to you during the whole day
4. Reduce training-day stress where possible
Stress is a major IBS trigger:
Build calm routines before runs
Avoid rushing meals or workouts when possible
These steps often reduce symptom intensity and help runners feel more in control while seeking professional support.
Product of the Week
This week's Product of the Week is Caudalie Vinosun Protect - Invisible High Protection Stick SPF50.
This is my favorite stick sunscreen for running.
It's reasonably priced, glides on easily, isn't sticky, doesn't leave a white cast, comes in a good size (which you can carry with you to reapply if necessary), and provides very effective protection.
I think I've used about five or more of these.
I'm a big fan of this brand, and the good thing is that it's available in most countries.
IBS can affect running performance—but it doesn’t have to stop you from running well.
With proper diagnosis, supportive nutrition strategies, and individualized care, runners can:
Train more consistently
Fuel with confidence
Reduce symptoms over time
Protect long-term gut and athletic health
Running should feel empowering, not stressful. When gut symptoms are addressed with care and evidence-based strategies, performance and confidence can follow.
Track of the Week 🎧️
This week's Track of the Week is a song I discovered recently, and I thought was perfect for a run in zone 4 or 5.
I’ve chosen Embers by Robin Schulz
Any questions or something you would like to share, drop me an email
Wishing you a great weekend and week ahead!
Here’s to health and good runs⚡️
Ana Paula Alonso