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The secret to avoiding stomach issues

Updated: Oct 19, 2021

It is no secret that nutrition is the 4th discipline in triathlon and the longer the distance the more important it becomes. You can train all you like, recover like a king and make all the right steps. If your gut is shutting down it certainly will all go down the drain. A bit of a shame if you ask me. Why train hours and set early alarms if you cannot even perform averagely on race day and enjoy the experience? There are many who never experienced any issues during training even when taking the same nutritional products such as gels, sports drinks etc. but come race day they struggle. Why is that? Being a Physiotherapist and having experience in functional Osteopathy I believe I found a missing puzzle piece not mentioned in literature I have read so far. You will find it at the very end of this post.

Let’s have a look at some research for common GI (gastro intestinal) distress during races:

Overconsumption of carbs

A study published in Medicine & Science in Sports & Exercise recruited 221 athletes who took part in two IRONMAN, one 70.3, a long cycling time trial, a cycling stage race and a marathon. They were asked to recall their nutritional intake and mention a variety of different GI distress symptoms and scale it from 0-9. Grams of carbs per hour were recorded in all events.

Turns out that 31% of all IRONMAN triathletes experienced GI symptoms and 14% of all 70.3 participants. That a whopping percentage if you ask me. On the other hand, only 4% of all marathoners experienced GI symptoms. There is a significantly higher rate of grams of carbs per hour in triathlons (62-71g/hr) compared to marathon running (35g/hr).

That would mean: the higher the rate and amount of carbs we take in per hour the more likely we are to experience GI distress.

That is no entirely true though. There was no association between higher carb intake with the runners, cyclists or 70.3 racers of that study. ONLY IRONMAN racers faced a greater risk of GI issues when they consumer more carbs. Although the athletes in 70.3 and full IRONMAN took in the same amount, only the full distance experienced more GI distress on average. Moreover, the GI distress in a 70.3 was twice as high as the risk in a cycling stage race despite having similar durations of racing. That means that the transition from cycling to running adds another stressor on your gut, probably in the first 10k running.

In short: Too many carbs per hour during a full IRONMAN are linked to more likelihood of GI issues. The length of the event influences the chance of GI distress as well as the transition from cycling to running.

Although all of us should be very familiar with the intensity of your race pace (not the full duration of the event but in intervals) coming close to race day is exciting. Stress can range from nervousness and fear of the event to just having too much on your plate the days before the even like private problems, work and so forth. Either way, if you find yourself in this state of anxiety and “feeling stressed” your nervous system is responding to that. Besides a number of physiological responses to that such as not being able to recovery properly, your gut will become more sensitive to anything really. Why do you think you are feeling tension and discomfort in your stomach area when you are stressed? It is all linked and explainable. I imagine you understand that if you hit the run course with an already sensitive and irritated body including gut, a few sugary gels will not necessarily improve your GI sensations while hammering along the race course at a high intensity.

So, make sure you eliminate any potential stressors in race week. Plan ahead and try to have a smooth week with good nutrition, hydration and sleep while sticking to your coaches training plan. No experiments anymore with anything, not in race week – the ship has sailed now. You are of course allowed to feel excited and even a bit nervous. It is a good reaction of your body since it primes you to optimal performance. Also watch your language in choice of words. “I am scared” or “fear” have nothing to do in your vocabulary. Exchange them to “I am excited” or “I look forward to the challenge”. That will put you in the right mindset. No space for negative thoughts or emotions, you trained too damn hard for that event to let it be influenced by that. Trust your training.

Timing and general nutrition

There are a few reasons why you could experience stomach bloating, burping, cramps and so on during racing and not in training. Remember the following reasons are highly subjective and it might be like that for some but not for others.

Simple solution: try it in training, that why it is called training – so you can do anything which you do not want to test out when it actually matters, in the race.

Possible reasons for GI distress on race day:

  • High amounts of fibrous nutrition the days before the event and race morning (for example. Oats, cereals, beans, lentils, berries, rye, bulgur etc.)

  • High fat and protein intake the night before and race morning

  • Generally, not having digested anything you had for food (my advice: do not eat lots of pizza the night before and squeeze it all in at 8pm. I did that before IRONMAN Copenhagen once and couldn’t get anything down on race morning, recipe for disaster. Also, on race morning eat at least 2.5hours before warming up for the race. Watch for too much caffeine intake, stick to what your body knows)

  • Swallowing air during the swim or while sipping from water bottles.

  • Too much of any nutritional intake (carbs, protein, fats, electrolyte) without adding enough fluid with it. Ready to clog the pipes?

  • Becoming dehydrated before or during the race (also make sure you add enough high-quality salts like Himalaya salt 2-3 days before the event. Although studies are not sure about sodium loading, making sure your electrolyte balance is in check is crucial. Many people flush out all nutrients with plain water. Color of urine should be slightly yellowish, not crystal clear white)

  • Medication and supplements (chronic use of aspirin and NSAIDs have been shown to damage the intestinal wall. I for example get sick when I take Magnesium supplements on an empty stomach, so just take all the night before and it will be fine)

"Training the gut”

There are studies (for ex. “Jeukendrup Training the gut for athletes, Sports Med. 2017”) who are talking about training with large volumes of fluid, training immediately after a meal, training with high carb intake and increase content of carbs in diet to ultimately improve performance. Yes sure, if you agree you can go ahead and do that. I personally, disagree with that approach. You obviously have to be certain that you can take a certain product and you are happy with it, maybe try it a few times in race pace sessions. Other than that I will stay away from it. I also think it is a great way of marketing and buying more of their products. There are studies that back up my beliefs. Take me as an example: I have not touched a gel after July 2017 up to my main event IRONMAN Florida in November except for Challenge Davos Half in September. I experienced absolutely no stomach issues and could take gels 30k + onwards in the Marathon in Florida without GI issues or discomfort of taste. That being said, from my first to 4th IRONMAN I suffered from GI distress during all races, always on the run. I cannot tell you exactly what the reasons is that they are gone now but my guess are 1) experience in long course racing 2) mainly fluids on the bike except for one bar after 140k to avoid the feeling of hunger and have something salty).

Biomechanical view

The role of the Aeroposition:

If you are sitting extremely tight and low on the bars you will produce more pressure on your organs including your gut. If you push these limits and you are making your gut work hard while performing at a high intensity, there is a chance you will experience GI distress. Make sure you spend enough time “behind bars” on your TT bike and practice drinking and nutrition in that position over longer periods of time. There should be no surprises come race day.

Make sure you get a proper bike fit done by professionals. There are way to many out there that are just trying to make some extra cash. I highly recommend STAPS ( for all the European based athletes, good enough for Mister Frodeno so cannot be too bar. And no, it is not overpriced if you might worry now, check the website.

Now we come to the functional osteopathy side of things. I will give you a brief background so that you will not ditch another foam roll session in your life.

Generally, the spine is in the center and can be split up in different sections such as cervical (neck), thoracic (upper to mid back) and lumbar (low back area) spine. The body is the master of compensation, meaning if you have an overload or old injury somewhere it might lead to a compensation in your spine which can cause a variety of issues. It goes as far that if you break your little finger, it will be represented in your spine, to give you an idea.

Depending on how you get a change in joint position in your spine, it affects different areas which have a neurophysiological connection. Common example would be the “tennis elbow” which is connected to the upper part of your thoracic spine. Unblock that one and activate the right muscles and you are as good as new.

Let’s come back to your gut and racing.

The area that is very much connected to your gut is your upper back/thoracic spine. Here is a list of the level of that vertebrae and the neurological connection that might get affected if that joint position changes:

T2-5 (2nd to 5th vertebrae upper back for ex.): Breathing volume restriction, functional lung problems

T6-9: stomach issues like pressure sensation and not tolerating nutrition (ding dong looks who’s here), issues regarding digestion, generally tension upper stomach and swellingness feeling.

T10-12: kidney issues which tends to cause swelling, intenstine problems and digestion issues, breathing problems and tension change in diaphragma/breathing muscle in stomach area

L1-2 (upper lower back/lumbar spine): digestion issues like constipation, flatulence/gas production

I am sure you get the message here. If you are having too much tension and blockages in that part of the spine (shoulder area down to upper lower back) due to let’s say spending lots of time in the TT position, you are more likely to experience GI distress. Especially during a triathlon you are pushing limits and hitting high effort levels on the bike. Combine that with already a lot of unresolved tension in the spine (also: office work or physically demanding jobs) from months of training leading up the event, and voilà the toilet seat is yours. We do not want that, so what to do?

  • Keeping the spine flexible (most important movements would be rotation and extension)

  • Foam rolling: make sure you roll nice and slow back and forth all the way from shoulder blades to lower back. Once you found a stiff area, lower your hips/sit down then hands behind head and extend yourself over the foam roll. All pain free, go slowly back and forth and try to get a little further each time. Examples: 3x 10 reps slow back and forth rolling followed by 6x 1min slow extending on stiff area with hips on floor.

  • Lumbar rotation stretch. Just google and youtube this one, very common. Goal is to reach the floor with both knee and opposite shoulder. Example: Hold 3x 1min per side while releasing all tension consciously and breathing deep and relaxed through your belly.

  • Massage

I am a firm believer in massage therapy, I go at least once a month if possible every two weeks in intense weeks. Mainly a financial issue, otherwise I would go once a week 😉 If you are in Zürich make sure to stop by a real professional like Mahmoud in Homes place in Horgen. (

  • Physiotherapy or Osteopathy

There are complex chains of compensations that need a sharp brain and good hands to deal with.

Wow, that filled up quickly again. I had fun writing and I hope I can help out a few lost triathlon souls who are frustrated and doomed with GI distress on your big day.

Until next time,

Become the most unstoppable you,




“Funktionelle Osteopathie und Integration”, Friedhelm Becker und Hand de Jong

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