Nutrition for IRONMAN Tallinn 2021 with Maurten and the Supersapiens sensor, by Yannick Antoine

After 12 Ironmans, I have to admit that I still hadn’t found the formula for perfect nutrition. I’m starting to know myself when it comes to physical training, and I know what I’m theoretically capable of doing in an Ironman, but I had never been able to put it into practice. Nutrition has always been my weak point: stomach issues, loss of energy and drowsiness during the marathon (and sometimes even on the bike!), hypoglycemia—I’ve experienced it all… several times 😊

This time, while preparing for the Ironman in Tallinn (Estonia), I placed particular focus on nutrition, testing and measuring my needs during training and my ability to assimilate the energy required to last through an Ironman.

Here are a few key points that guided my thinking:

1. Pre-race nutrition/carbo loading

I often arrived on race morning having probably eaten too much in the preceding days and having fallen for the brands’ marketing sirens (eat a lot = buy a lot). The result: bloating, water retention, and sometimes stomach issues even before the swim start!

For this Ironman, I ate “normally” for 3 days, but prioritized starchy foods (pasta/rice), without trying to “stock up.” I supplemented these 3 days with 1 500ml bottle of Maurten Drink Mix 320 per day.

2. Race: energy requirements

The recommendation is to assimilate 1g of carbohydrate per kg of body weight per hour of racing.

It is possible to go beyond that by combining different types of carbohydrates (glucose, maltodextrin, fructose), but this must be tested.

In the past, the energy drinks I used were often too low in carbohydrates. I therefore had to supplement them, either with gels or bars. In practice, I was unable to assimilate the necessary calories without once again experiencing stomach issues that greatly hindered me on the run.

In addition, the strongly sweet taste (orange, lemon?) of commercial drinks creates an aversion to sweetness for me, which greatly affects my ability to continue refueling with the organizers’ drinks during the marathon.

3. Managing nutrition on the bike:

It is impossible to carry more than 2.5l of fluid on my bike. So I need to get the calories in the most concentrated form possible through the energy drink, and potentially supplement it with a few gels/bars while preserving digestive comfort

In practice:

For all these reasons, and because I had tested their drink in the past, I chose to focus on Maurten Drink Mix 320: one sachet diluted in a 500ml bottle provides 80g of various carbohydrates. For 5 hours of cycling, I therefore only need “5 500ml bottles,” and by increasing the bottle size I can carry almost all my nutrition on the bike (or potentially plan a single personal aid station to pick up a bottle on the course if this is allowed).

So there is no longer any need to slow down at every aid station and try to grab bottles on the fly.

I supplement this with 2 CLIF bars, which suit me well but can be difficult to chew while riding because of their texture. Limiting myself to 2 bars over approximately 5 hours allows me to take about ¼ of a bar every 30 minutes, which is easier to chew and assimilate while avoiding the feeling of an empty stomach.

At the same time, I usually consume mineral salt tablets as a supplement. The amount may vary depending on the weather conditions. In Tallinn, with 18°C temperatures and rain throughout the race, my needs were limited (3–4 tablets in total).

4. Validate it in training:

In an Ironman, the goal is to reach the half-marathon feeling fresh and having filled up on calories without any problems. To validate my protocol on the bike, I used the Supersapiens glucose monitor.

In real time, and also afterward, I could see how my blood glucose level varied thanks to a patch stuck to my arm and an app on my phone.

On long rides (5–6 hours and up to 200 km), this allowed me to validate and fine-tune the Maurten Drink Mix 320 + CLIF bar protocol, ensuring that my glucose level did not drop but instead remained stable thanks to regular consumption.

5. Running:

Once the cycling protocol had been tested and validated, all that remained was to manage nutrition during the run. It is difficult here to carry 1.5l of fluid for a 3-hour run. So I relied on Maurten 100 gels, having successfully tested them in a race at the Ironman 70.3 Les Sables d’Olonne. They are also very easy to digest despite their particular texture and do not create an insulin spike or an aversion to sweetness.

I therefore started the marathon with 5 gels, which I took with water at the aid stations, alternating them with the organizers’ energy drink. Once I had finished my Maurten gels, I had already reached the half-marathon mark, and only then did I switch to the organizers’ gels and drinks as well as cola to supplement. At that point, the mental aspect takes center stage, and being able to swallow whatever I wanted without stomach issues or an aversion to sweetness during the final part of the race made it significantly “easier.” In the end, I beat my Ironman marathon record, running at an average pace of 4’27’’/km (every kilometer between 4’10’’ and 4’40’).

Even better: I feel tired but not destroyed at the finish. Good hydration throughout the race and a good calorie intake allowed me to hold on for longer, but also to recover more quickly.

Of course, this is the protocol that worked for me and may not be suitable for everyone, but it can serve as a basis for reflection to help create your own plan with the assistance of Nutri-bay’s experts 😉