As a triathlon coach I often hear a series of questions about nutrition strategies for Ironman racing. Training for an Ironman triathlon is a task itself without having to think about race day nutrition. In long course racing, like the Ironman triathlon you need to practice and tune your nutrition strategy starting months out.
In this article I've included solid tips which are good guidelines to start with in your Ironman nutrition planning. Keep in mind everyone is different and you must practice these nutrition strategies months before your key race and modify them as needed. With my Ironman athletes I like to have them do what's called a "Big Training Day" of swimming, biking, and running with Ironman stimulation a couple of times at different points leading up to their race. It's a long day but a good opportunity to practice to find out how their nutrition will respond and how they can overcome challenges that may arise. When the actual race is here they are prepared.
Two Days Before you will want to slightly increase your protein, carbohydrate, and salt consumption. Athletes need to consume 1.4-1.8 grams/kg of protein per day and 5-6 g/kg per day for carbohydrates while limiting fiber. Limiting fiber will help prevent GI distress. A bowl of a soup is a great way to increase your salt intake. The day before you will want to eat a large breakfast and lunch with both meals having a low glycemic index and fiber.
Over hydrating before your race can lead to hyponatremia. This dilutes the sodium at the cellular level. If you are peeing every 2-3 hours a couple of days before this is solid evidence that you are adequately hydrated prior to competing as long as your urine is fairly clear - anymore than this you should be concerned. Over hydration leads to nausea, vomiting, and cramping. (My own experiences).
Electrolytes plays a critical role in racing, especially in the Ironman triathlon. There really isn't a need to increase your electrolytes too much before the race unless you are a profuse sweater. You may want to visit my last training blog on hydration to do a sweat test. If you are a serious sweater then increasing your salt consumption 800-2000 mg during your dinner the night before may help. You can easily get this amount with a bowl of soup. Electrolytes do help you while racing, especially 4-5 plus hours. They help with digestion by moving water through the cells. You should take 2-4 electrolyte tablets per hour (ex. endurolytes) depending on the heat, sweat rate, and effort. We preach this often that is to practice in race pace training stimulation.
Race day breakfast is extremely important for the Ironman athlete. Here are three different options depending on how your body responds in training at race simulation paces to see which one works best for you.
If you require a substantial breakfast (600-800 calories) before long course racing you may need to eat 2-3 hours before your race start to give you plenty of time to digest. You should keep this rich in carbohydrate and very low in fiber. For something lighter (200-350 calories) eat a more liquid based digestible meal about an hour before. For something on the opposite end, if you need a huge breakfast of 1000-1500 calories. It should be consumed approximately 3-4 hours before. You will want to rehearse these options in training and during low priority races. If you find yourself with a sensitive stomach you will want to practice more with semi to complete liquids.
Thirty minutes before your Ironman consume a maloxdextrin or dextrose (glucose) based gel. This malodextrin based gel is more complex than dextrose/sucrose based and takes longer to break down. Consuming these during the race could lead to GI distress, but 30 minutes before you should be safe - with just one. Again, you will want to experiment in training first! You can switch to a simpler form on the bike and run.
Once on the bike divide your nutrition and effort into four segments. During the whole bike most triathletes will take in 30-50% of their calories from solid foods (bars, sandwiches, cookies) aiming for 200-400 calories/hour based on your tolerance, size, and experience. During the first quarter of the bike avoid going too hard and let your heart rate do the talking. You will see many people going by on your left, but don't worry you will be catching them a few hours later on the run when their legs are cooked. Going too hard too early will mess up your digestion and your race will end in a disaster. Keep your heart rate below zone 3 the first 30 miles. If it goes over then you are going too hard. The second quarter of the bike it should still be much in zone 2 holding steady at Ironman goal watts. Usually only the fittest of the fittest triathletes can tolerate riding an Ironman in zone 3. The third quarter of the Ironman keep holding steady of zone 2 effort, even though your heart rate might be reading higher. It's even better to have a power meter to dial this in. The last quarter of the ride still try continue to eat and keep your effort similar to zone 2 to moderately hard. Your heart rate will probably be reading quite higher by this point. Any point during the ride you are facing stomach issues you need to slow down. Trying to deal with your stomach issues by keep pushing will only make it worse and you will lose more time on the run than you would by slowing down on the ride.
On the run you should avoid solids unless you are on walk to the finish line trying to regroup. It would be near impossible to consume solids while running. Most of your nutrition will come from liquid such as water, sports drink, gels, and Coke. Aim to consume about 100-250 calories per hour. At the beginning of the run settle in at a very easy pace and consume liquid calories. Avoid picking up the pace too much and get settled in. Save your biggest effort for about the last 8 miles. At every aid station take in a gel with 6oz. water, sports drink, or coke - not all at the same time. Although not enough evidence or studies to make a strong case, but some suggest that consuming ice water will slow down the rate of digestion further.
You will want to hit the coke late into the run as it's the simplest form of sugar, glucose (dextrose). It's important to know if coke will be available on the course. A drink mix of dextrose/sucrose (not gels) will help as dextrose requires really no digestion. If your fuel options aren't available on the course, you'll want to carry your own to something similar to a Fuel Belt or Nathan brand. In the last 8 miles if you're feeling well and you can run faster, you will gain a lot of time on those who went out too hard at the beginning, just be sure to keep up with you nutrition.
Gels can be finicky for some individuals a long with the marketed endurance drinks. The malodextrin based gels take longer to digest and the dextrose based gels tend to have higher osmolarity, both of these could lead to GI distress.
Fortunately, there are some alternatives out there with a bit of research - homemade gels, fat added gels, or energy chews. Pedialyte is also a common beverage for endurance racers who have stomach issues. You'll want to practice experimenting months in advance before your Ironman with different options.
Regardless, no matter how hard you try it is extremely difficult to replicate race nutrition strategy in training. You can certainly prepare the best you can but sometimes things happen when you least expect. Your body may respond differently than it did in training. It helps to be equipped with this information so you can be best prepared. Not everything will go perfectly. It may take you several Ironman triathlon races to develop a solid nutrition strategy. Chrissie Wellington said it took her 5 tries. The main thing is to remind yourself to be positive in the moment and deal with the cards you are dealt with at that point in time.
Thanks for reading!
If you have questions or an idea for another topic that would be of help to you, simply leave a comment or email. If you are interested in coaching, review my coaching page first then email me for an interview at firstname.lastname@example.org. I have limited availability open for coaching passionate athletes who want to get the most return for their investment of time. I'm currently coaching a great group of athletes beginner to elite with different goals (Ex. Finishing first triathlon, 70.3 or Ironman, Boston qualify, Podium finish) from East Texas/Dallas all the way up to Maryland .