Ultramarathon Nutrition - Part 2

Optimal Carbohydrate, Protein, & Caffeine intake during endurance events

A few days ago I posted a blog on my nutrition issues, and today when I listened to this pod cast with Asker Juekendrup on competitorradio.com, I was surprised to find out that it was all about nutrition.

So who is Asker Juekendrup? Well he is is one of the leading sports nutritionists of the Human Performance lab at the University of Birmingham. He has previously worked with the Rabobank professional cycling team, and is currently working with high profiled athletes such as Chrissie Wellington (Ironman winner) and Haile Gebrselassie (marathon world record holder). He has also personally completed 17 Ironman Triathlons.

The pod cast runs for 50mins but I think that it's well worth a listen. Here is a quick summary of the findings of his recent studies:

1. The optimal carbohydrate fuel source is made up of 2:1 ratio of glucose & fructose. Glucose alone can only provide around 60 grams/hour, but because glucose and fructose are absorbed differently in the intestines, it allows for a higher amount of carbohydrate to be absorbed. The approximate ratio of 2:1 allows us to consume approximately an extra 30 grams of carbohydrate per hour. An interesting comment that Asker made, was that because the digestive limitations are due to the nature of our intestines, and because both large and small people have similar sized intestines, then the amount of carbohydrate that is able to be absorbed is very similar for both large and small people. Also, whilst the absorption of the 2:1 mix is slightly impaired, it closely matches that of water alone.
2. According to his studies he doesn't believe that protein is necessary during endurance events such as the Ironman. Firstly, protein will impair the rate at which carbohydrate can be absorbed, and for events of Ironman distances he doesn't believe that the mechanisms claimed by many studies can work in that time period. From what he said in the pod cast, it's not clear if protein would be useful for events lasting over 24 hours or so.
3. Caffeine clearly has a performance enhancing effect. The recommended dosage is 3-5mg per kg of body weight. As caffeine has a half life of around 5 hours we only need to top up every 5 hours or so. Studies also show that more is not better, and it's a good idea to stick to the recommendation of 3-5mg per kg of body weight.

So there you have it. The findings of Askers studies are different to Hammers philosophy, but who is correct? As with a lot of this stuff, I think we need to test it out during training and figure out what works best for us. We are all different!