How To Fuel During Your Ironman Race

Come race day; there are plenty of athletes who experience the horror of being unable to complete the Ironman events due to gastrointestinal issues, sickness, dizziness or extreme fatigue; all due to inadequate nutrition during the race. Dehydration is the biggest issue that competitors face, but poor nutrition comes as a close second. During an event as big as Ironman, it’s essential for triathletes to look after their body correctly and make sure they have enough fuel to burn. The most important thing to remember during an Ironman event is that how you decide to refuel yourself can be the deciding factor as to whether you cross the line with your best time or cross the line burned out and unhappy with your performance.

When competing in an Ironman event, it’s crucial to have a thoroughly thought out nutrition plan. During shorter races, it’s best to stick to gels or sports drinks. However, during a full Ironman event, you’re going to want to fuel yourself a bit more. The average Ironman triathlete will lose 6,000 calories in-between the start and finish line. It’s worth remembering that before a race is started, your body will already have around 90-120 minutes’ worth of energy (glycogen) stored in the muscles if you have a well maintained, balanced diet. It’s glycogen which fuels the body and its this fuel that will keep you going during an event, so it's essential to keep it topped up. For long events, your best friend is carb-loading, gradually, prior to the event and then fuelling on quick release carbs on the day.

The way you fuel up during an event depends primarily on your gender, size and the temperature, terrain and intensity of the race. Your goal during the race should be to replace roughly 30-50% of calories burned.
However, how do you take on all these calories during an Ironman event? However you decide to refuel yourself, there are some important tips to remember:

The Morning of Race Day
Ask any athlete what they eat on the morning of a big event, and you’ll receive a multitude of different answers. The overall guideline is, whatever you’ve been eating before training is what you should be eating on race day. Never, ever, try eating anything on the day of the event that you wouldn’t normally eat. The day of Ironman is not the day to be trying out new foods and new methods. This includes excessive amounts of caffeine. You should know by now what foods keep you going best, and which foods don’t go down too well.

The Swim
The general rule of thumb is to not eat anything during the swim. This can be dangerous and should be avoided, but it’s also just not necessary. The best time to refuel is during your transition from swim to bike and during your time at the aid stations. If you’ve been maintaining a well-balanced diet in the months before the event, your body should be well nourished to keep you going. It’s best to have a sports drink or gel before and after the swim.


During T1
After the swim, you’re likely to start feeling some level of normal fatigue. It’s best not to wait until you’re experiencing hunger pangs before you decide to have something to eat. Eating little and often, every now and again is the best way forward, so your body doesn’t suddenly start running on empty. The most efficient way to fuel up during your transition from swim to bike is to chew while changing clothes or donning your helmet. Take a second to have a breather and a mouthful, to avoid cramping or digestion issues.

The Bike
The most natural time to refuel (apart from in T1) is when you’re on the bike. This is mostly because your stomach isn’t jostling about as much as it would be during the upcoming run, meaning you’re less likely to suffer from stomach upset as your nutrition has time to settle and be absorbed. It’s easy to carry around nutrition on the bike, as you can attach bottles, gels and solid foods such as energy bars and sandwiches or use pockets on your triwear. The nutrition you consume during an Ironman event needs to be fast-release carbohydrates so as your muscles can gain energy as quickly as possible. The best nutrition when on the bike is:
- An isotonic sports drink (even just using this as a mouth rinse is an excellent way to keep the brain focused)
- Carbohydrate energy gels
- Jellied sweets
- A banana
- Cereal bars or low fibre carbohydrate-based energy bars



During T2 
If you fuel yourself adequately on the bike, you’ll find that you might want to push through T2 without eating. If, however, you feel the need to, it’s best to consume gels and energy bars during this second transition. As done in T1, take your time to eat correctly and safely and make sure you’ve caught your breath. It’s much, much better to take the time now to fuel yourself up than ‘bonk’ during the run.

On The Run
The most important thing to remember when fuelling up during the run is not to try and eat while you’re in full stride. This isn’t just ridiculously difficult to do, but it can result in choking and digestion issues which you definitely won’t want to experience while on your last leg of the event. In faster races, you will need less to get you through it. During the longer Ironman distances, multiple gels, bananas and other foods may be necessary. You should check what will be available at aid stations before you set off and use them accordingly. Don’t be afraid to have a higher carb, higher energy snacks. You’ll need them.


The most important rule to remember during any event is that you absolutely should not try anything new on race day. It would be best if you had a well thought out nutrition plan weeks before the event. It’s not beneficial to consume things you’re not used to during a race, as you might experience unpleasant side effects.
Whatever you choose to do on the day of Ironman, make sure that you listen to your body. If you feel any hunger pangs, refuel. You might find yourself not wanting to intake any fluid but try anyway. Most importantly, you have to fend off dehydration. Gel packs, energy bars and ISO drinks are your best friends.



Written by Catharyne Walton-Matthews