A few of my athletes are approaching their first half Ironman. This means a lot of questions, many of which revolve around nutrition. When it comes to race day nutrition, a few basics that every athlete can start with are hydration, electrolytes, and calories. All of the guidelines I am going to lay out are just that: Guidelines. They are not set in stone and can change drastically based on the temperature, athlete, dietary restrictions, and nutrition history (aka the often repeated rule: do not try anything new on race day!). Practice with many nutrition products, including what they have on course. Know how you react to them, then make a plan.
Let’s get to the basics. In races over two hours nutrition can make or break your race. Make sure you show up on the start line with hydrated and with full glycogen stores. I try to eat a big breakfast and lunch the day before the race, then taper off my meals and have smaller snacks the rest of the day. My breakfast is typically carb heavy and varies depending on what is available. For my later lunch, I like to eat a grain centered meal, such as rice with a little bit of chicken and veggies. I keep my snacks carb heavy as well, such as cereal and peanut butter and honey sandwiches. Race morning I eat a carb heavy meal about three hours before the race start. I shoot for 800 to 1000 calories from mixed sources such as a bowl of oatmeal, toast, and a banana. Peanut butter and honey usually accompany all three of these. I also focus on drinking water and some sort of electrolyte drink throughout the day before and morning of the race. If I feel like I need it, I have a gel right before the start of the race.
Once in the water I try hard to take in nothing. After getting on the bike is when the real fueling begins. This is the most important leg for fueling. In order to have a good run, you need to start as well fueled and hydrated as possible. I like to think about how I would fuel if I was going to run a standalone half marathon or full marathon. I would have a good breakfast and be well hydrated going in to those races, so I want to start the run leg as close to this state as possible.
The gut can process at most about 100 grams of carbs an hour. This is 400 calories of pure carbohydrate so likely closer to 450 calories with other macro nutrients. In order to actually process that much you need to practice. Smaller people may be lower. The range is about 250 calories to 450. This is affected by the intensity level, practice, and the source of the calories. I aim for the high end - about 400 calories an hour on the bike. When I started I maxed out closer to 200. This has been a learned skill I have worked on over the years. You also need to make sure you are consuming enough water and electrolyte in order to digest these. Minimum requirements are a bike bottle an hour, but I think two bottles an hour is a better goal, unless it is a cold race.
Electrolyte consumption varies a lot depending on the person. Some people just can drink a little sports drink while others take multiple salt pills an hour. This must be based on practice, but I believe that having some plan for electrolytes is important. Think about what you crave after a longer session. If you crave fries and chips - you are likely a salty sweater! You can also look at your clothes after a long ride. Are they white with salt? If so, you need to be supplementing with electrolytes. Again, water is key. You need to take in enough water to digest the electrolytes you are ingesting.
During the run of a half ironman I stick to 2-3 gels. I also try to alternate drinking water and gatorade at every aid station. It is much more challenging to take in calories while running. I find I max out closer to 250 compared to the 400 while riding. It may surprise you to hear that I switch to flat coke for the last third of the run!
I can’t say enough about flat coke. People talk a lot about eating clean, and racing on products with good ingredients. When all else fails flat coke seems to always work. My one word of caution, is to try to wash it down with a little water, and once you start, don’t stop! It is a fast fuel source, so you need to keep dumping it in! The point is, nutrition is key, but it might be simpler than you think. Play around and figure out what works for you!