We thought it would be fitting to provide an article this month in lieu of the Ironman World Championships fast approaching in early October. It is very common for athletes to either forget about their nutrition until the last few days before the event or have no idea the large impact it can make on the day of an Ironman race.
This article will provide you a few outside of the box nutrition tips as you develop your Ironman race day nutrition plan either for a late season Ironman or one that you may complete in 2012.
Tip #1: Beware of the blood shunting response
Many athletes will try their normal training nutrition plan during longer aerobic training sessions and while this is okay to a certain extent, it is important to remember that the gut will respond differently when the intensity of exercise increases. Specifically, there is a blood shunting response which means that during higher intensity exercise, more blood is directed to the working muscles so more oxygen can be delivered to support locomotion. This means less blood in the gut and thus when you try to eat something when pushing the pace a bit, your body responds negatively and you will either feel like you are going to throw-up or you must slow the pace down to redirect the blood flow back to the gut to process any calories you have consumed.
The solution involves not overfeeding your body with calories during exercise so the body is not confused regarding where the blood should go. Read the next tip to learn how to do this.
Tip #2: Develop metabolic efficiency
You have likely heard of the concept of metabolic efficiency but if you have not, I will outline it for you in brief because it has completely changed the nutrition paradigm for Ironman athletes. Metabolic efficiency is the ability of the body to more efficiently use the nutrients it has stored, specifically carbohydrate and fat.
The body has extremely limited stores of carbohydrate (enough to fuel about 2-3 hours worth of moderate intense exercise) but almost unlimited stores of fat. The goal is to teach your body to use more of its abundant fat stores during exercise. By doing this, you will preserve those precious carbohydrate stores longer thus you will not need to feed much during longer training or racing. By lessening your bodyʼs need for supplemental calories during exercise, there will be less blood shunting happening and the body (and gut) becomes much happier! Be forewarned though, like developing any type of efficiency, be it mechanical or nutritional, it takes a daily nutrition shift and about 2-4 weeks of nutrition training to begin the transformation to metabolic efficiency.
If you put in the small amount of time needed to make this metabolic shift, the rewards can be fantastic. Most athletes change their hourly calorie needs during an Ironman from 300-400 down to 40-120. That is music to an Ironman athleteʼs ears because as you learned in Tip #1, the more calories you put in your body during training, the more blood is shunted away from your gut and the incidence of GI distress is greater. Plus, you will not have to worry about your nutrition as much and you will actually be able to focus on racing without nutrition being a limiter!
The only true way to test the waters and apply these nutrition tips is to implement a nutrition plan during training sessions that have race predicted intensity built into them. The true test becomes when your bodyʼs thermostat best simulates your Ironman race so be sure to add about 90-120 minutes of race pace during your longer bike and brick sessions to test your metabolic efficiency and how your digestive system will respond with the added intensity. In the end, developing metabolic efficiency will support a higher level of performance and health.
Happy training!
Originally written by : Bob Seebohar coachbob@fuel4mance.com


September 19th, 2011
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