Triathlon Nutrition Planning for Training and Racing Ironman and 70.3

It’s that time of year again!  The weather is warming and the duration of key endurance rides and runs is increasing in preparation for spring long course races.  As such, you need to start paying attention to fueling.

The importance of fueling during training and racing

As the duration of your long rides (and to a lesser extent long runs) increases, it is essential to take in calories. Generally, if you’re working out (or racing) for over 90 minutes, you will benefit from taking in nutrition.  For long course races, like half or full Ironmans, in-race nutrition is the fourth discipline.  Knowing exactly what to consume during the bike and run is ESSENTIAL for performing well.  So now is the time to learn how your body absorbs and burns fuel during exercise and to establish what you can and should eat/drink during your longer sessions and races.

Prioritize carbohydrates, electrolytes and fluid

Your doctor might recommend that you limit sugar and salt intake in your day-to-day life. That’s good advice; however, you should completely ignore it when racing. Especially in long-course racing, intelligently consuming sugar (i.e. carbohydrates) and sodium (an essential electrolyte) can mean the difference between a podium and a DNF. (Note: don’t consume pure table salt or bags of sugar as pictured in the photo above. There are better alternatives).

Carbohydrates and endurance sports are inextricable from one another.  Carbo-loading, pasta dinners and sugary gels are heavily associated with running, cycling and triathlon—and for good reason.  Carbohydrates are the primary source of fuel during exercise. You’ve likely heard of the dreaded “bonk,” which is when your body runs out of glycogen (i.e. stored carbohydrates).  When you run out of fuel, your ability to continue at target pace evaporates and you are relegated to a walk or slow shuffle. When it comes to fueling during exercise, carbohydrates are key.

There are 4 calories per gram of carbohydrate.  Most people should aim to consume 60-90 grams per hour, or 240-360 calories worth.  This is by no means a ceiling, as many are able to tolerate 400-500+ during Ironman races while on the bike. Your ability to absorb carbohydrates is influenced by the intensity you are exerting (the higher the intensity, the slower the rate of absorption). Thus, you should be able to take in more calories per hour during an Ironman race or easy long ride than during an Olympic or 70.3 distance race. To establish what you can consume at various intensity levels, you need to experiment in training.

Of comparable importance to carbohydrates are electrolytes—specifically sodium and potassium.  Electrolytes are essential for maintaining osmotic pressure and for nerve function.  They form ions that carry the charge necessary for muscle contraction and nerve impulses, so when you’re depleted, your muscles cramp. Depending on sweat rate and composition (i.e. how salty your sweat is), I recommend that athletes consume 500-1000 milligrams of sodium per hour, and 250-500 milligrams of potassium.  Again, it’s important to experiment in training to figure out what works for you.

To adequately absorb carbs and electrolytes—and to simply replenish fluid lost via sweating—you need to consume liquids. The volume you need to drink is driven by your sweat rate (which is related to temperature, humidity and intensity level) and the number of calories and amount of electrolytes you are consuming. It is all about balance. If you drink too little relative to calorie/electrolyte consumption, the nutrition will sit in your stomach and you’ll feel bloated. Similarly, if you drink too much, there will be excess water in your stomach sloshing around, which is decidedly uncomfortable. Because of this, you need to figure out appropriate fluid/calorie/electrolyte ratios. There is leeway, but 100 calories per 8 oz of fluid is a decent ball park estimate, though you may be able to go more concentrated in cooler races or more diluted in hotter races. Most people can consume up to one liter, or 32 oz, every hour, though this is an upper limit that is usually reserved for hot days unless your body and experimentation during training demonstrates otherwise.

What about protein?

Many athletes ask about protein during an Ironman race.  In my opinion, there is no benefit to consuming it (assuming you aren’t engaging in some kind of multi-day event).  Yes, your body is breaking down muscle and protein, but it’s not as if consuming protein during your race is going to cause your body to repair itself while you’re biking or running.  All fat and protein will do is tax your digestive system, burning energy that should be spent metabolizing carbohydrates. A few years ago there was thinking that consuming a bit of protein (i.e. a 4:1 ratio) would be useful, but the evidence supporting it is suspect. Focus on carbohydrates and electrolytes. 

What to consume during training and racing? Gels, sports drink, etc.

The best approach is keeping it simple. There is no physiological benefit to consuming solid foods (though this can be enjoyable in training), so I typically recommend athletes go with an all liquid nutrition plan during races. Some people enjoy eating real food (sandwiches, pretzels, bananas, etc.) during key endurance sessions, which is fine early in the season, but as your target race approaches, you want to consistently practice your race day nutrition plan during training. This means testing and establishing a protocol that works best for you—which could mean a completely self-supported nutrition plan or utilizing the offerings at aid stations on the race course.

Gatorade Endurance and gels are available on the course at WTC (Ironman and 70.3) events and are common at other USAT certified races. You need to make sure these sit well with you before grabbing them for the first time in the middle of a race, so figure out what will be on the course at your next event and train with it during your key sessions to ensure you tolerate it. However, just because they hand certain items out on the course does not mean they are the best options for you or that you shouldn’t supply your own nutrition. Other great sports drink options that you can carry with you include Tailwind, EFS, Skratch and Base Performance Hydro, among others. Again, the key is experimenting to see what you like and can absorb.

Apart from sports drink, the next most readily absorbed nutrition source is gels. Products like GU or Clif shots usually come in 100 calories servings and are great supplementation. Some prefer to subsist off of them exclusively and wash them down with water—taking in one gel pack every 20 minutes or so. These people will often grab water on the course and store the gels on their bike and/or in their pockets.

Consolidating your nutrition

An alternative strategy to carrying numerous gels or keeping track of a half dozen 200-300 calorie bottles of sports drink is mixing one highly concentrated bottle and supplementing with water. An approach I often recommend to athletes and utilize in my own racing is creating a 900-1,500 calorie bottle of sports drink or multiple gel servings diluted with a bit of water. The result is a slightly thicker solution that you can wash down with additional water that you obtain on the course. You can use a permanent marker to mark volume increments along the side of the bottle so that you know how many calories you are consuming in real time. The benefit of this is its simplicity and knowledge that most of your nutrition is consolidated into one traceable bottle.

Example Nutrition Plans for Ironman and 70.3 Racing


-Once on the bike, start with a 300 calorie bottle of Tailwind between the aero bars and another behind the saddle (600 calories total). Supplement with a bottle of Gatorade Endurance on the course or a gel or two that you bring with you in the pocket of your trisuit. Aim to take in 250-300 calories per hour.

-On the run, take in a gel every 30 minutes with water at every aid station. Alternatively, take in a bit of Gatorade Endurance at each aid station, trying to balance the volume you’re consuming with your effort. You want to take in a fair amount, but you don’t want it sloshing in your stomach or causing bloating. Adjust as you progress through the run. 12-24 ounces of liquid per hour is certainly possible, but again, you need to be reading your body.


-On the bike, start with a concentrated 1,200 calorie bottle of sports drink on the bike. Supplement with three caffeinated gels evenly distributed throughout the ride, and two bottles of Gatorade Endurance. Take in 300-400+ calories every hour.

-On the run, take in a gel every 30-40 minutes and supplement with as much Gatorade endurance as your body can comfortably absorb. The key is adjusting consumption relative to how you are feeling and digesting.


Don’t wing it. Figure out what your body needs and can tolerate in training. This will likely mean 16-32 oz of water; 250-400 calories of carbs; 500-1000 mg of sodium and 250-500 mg of potassium per hour.

Conrad Goeringer is an Ironman Certified Coach based out of Nashville, TN. He is the founder of Working Triathlete and author of the book The Working Triathlete. His passion is helping athletes of all levels and with all schedules achieve their endurance goals. Reach out to learn more about coaching packages and for a free consultation.