More on Big Unit Fueling

by Nicolas Theopold

As a tall and relatively heavy (85kg) guy I need to produce a lot of power to get around an ironman course, which means a big energy need. Due to my size, my energy stores are likely bigger than average, but like for everyone else, they are far too small to get me to the finish line.

I will start a race with somewhere around 3,000 calories in my stores, but will need around 9,000 calories to get to the finish line. This means I need to get 6,000 calories from other sources -- either fat or race day nutrition intake. So when I look at fueling, I look at energy production and fuel intake during the race.

Energy production
A big piece to understanding the puzzle was the substrate test I did earlier this year with Alan Couzens. For those who are unfamiliar with it -- it's a bike test on a home trainer during which we measured the breathing gases. The respiratory gases told us how much energy I was generating from fat and how much from carbs at different levels of power.

Assuming that the machine was well calibrated I was happy to see that I was oxidizing very large amounts of fat in absolute terms and was still at 50% of energy coming from fat at ironman pace. Unfortunately, I also learned that I am not very efficient at producing this energy: I take far more oxygen to produce a certain amount of power than a top level triathlete, which means that I use more energy to produce a watt than an elite athlete. Not so good.

To help fat consumption we continued to focus on extensive endurance and on a diet high in healthy fats. I really upped the number of avocados I am eating, as well as the amount of olive oil and nuts I'm eating. That said, I still need to take care to get enough carbs to fuel consistent training day in and day out. There is no point in starving yourself of carbs to the point that you bonk during training.

To increase efficiency we focused on strength, which has been shown to affect cycling efficiency positively. I haven't done a follow-up test yet to see whether the numbers have changed significantly, but recent training results have been encouraging.

Race fueling
In past races I found that my gut starts getting iffy around 7 to 8 hours of racing. I can usually pull off a half ironman with aggressive fueling where I take on 400 calories per hour on the bike and still run pretty hard afterwards. During my previous ironman races I hit the nutritional wall somewhere between the first and second hour of the run. It was never game over, but it's pretty unpleasant and did slow me down.

For the coming race I'm changing things with Alan's guidance in the hope to get through it better. I am taking out pretty much all solid food and gels and am going to liquid nutrition, which should be easier to take on. I've also tested -- and very much liked -- using maltodextrin that is taste free and mixed with water. You can buy it at pharmacies for a low cost and mix your own bottles. It's super easy to drink on the bike and doesn't give me taste aversion like gels or other things later on. During the run I will switch to Coke only and keep an emergency gel in my pocket.

Nutrition simulations
The last piece of the puzzle is in pushing the nutrition envelope during training and to back off during the race. I am trying to be aggressive in my fueling during ironman simulations and try to get through, but at race day I will take my consumption down again by a notch to maximize my chances of getting through without stomach problems.

This whole experience has shown me that with a bit of curiosity and trial and error you can make some big improvements in your race nutrition and enhance your chances of having a great race day. Don't leave things up to chance -- you trained far too hard to get to the start line to throw away the race with a poor nutrition strategy.

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