In shorter distance triathlons you can typically get away with making some nutrition mistakes, but during a 70.3 or another 4 – 7 hour event, nutrition is an incredibly important factor.

The aim for a bike leg of an Ironman 70.3 is to propel you strongly to the start of the run. The aim of the run is have enough fuel left in your body to show off your fitness. If you have practiced sound nutrition over the 56 miles of riding, you will be able to begin the run in great condition and complete the 13.1 miles with minimal slowing down. 

The sport nutrition products supplied on the course do not necessarily guide your choice of calories. You can train with those products in the months before the race to test them. Most athletes work with the product that suits their stomach and do not cause GI distress.

Note that calorie absorption and heart rate are inversely related. As you start to exercise blood is diverted from your stomach to your working muscles and skin to sweat and help cool you. As your heart rate rises, you are less able to digest the calories you ingest. Therefore your race day nutrition plan is intimately bound to your racing heart rate. Make sure you show up to the race knowing your race intensity zones and having practiced eating at those heart rates! The most common mistake is to consume too much at a high heart rate. If your heart rate is up, adjust your calorie intake downward. Also, do what you’ve been doing in training – don’t try anything new on race day!

When preparing your race day plan you should take the following guidelines into account:

Pre Race

  1. Breakfast on race day should be similar to training days. Stick primarily with carbohydrates, a little protein, and minimal fats. Toast and jam, a banana, oatmeal, PowerBar, and Carbohydrate electrolyte drinks are popular choices. Some will have egg or peanut butter for protein. Some athletes prefer a shake. If you have a coffee on training days, have a coffee on race day.
  2. Finish breakfast 2-3hrs before race start to give yourself time to digest.
  3. In the 2hrs before the race, sip water and/or a Carbohydrate electrolyte drink.
  4. Some athletes will take a PowerGel prior to race start.


  1. Starting the bike – For the first 5-10 minutes of the bike, drink water and take in minimal calories, mainly in the form of a sports drink. Let your body adjust to cycling, and let your heart rate drop down. Then start eating when you have settled into a good cycling rhythm. Follow the plan you’ve trained with all season, do nothing new on race day.
  2. From 10 minutes after the bike start to 10 minutes prior to the bike finish eat 200-350 carbohydrate calories per hour, regardless of source. Larger or muscular athletes tend to need more calories. For instance, PowerGel = 110 cal; PowerBar = 200 cal; Carbohydrate electrolyte drink = 100 cal. Bigger athletes need more calories. Some athletes can digest more than others. Test it in training.
  3. Drink 1 to 1.5 litres (33-50oz) of fluid per hour (water and Carbohydrate electrolyte drink combined). This is approximately 2 small bottles to 2 large bottles per hour, depending on climate and your personal perspiration rate. A training tip is to weigh yourself pre- and post ride.  Every 1 pound lost is 1 small water bottle of fluid deficit, and will negatively impact your half marathon performance.
  4. Set your watch alarm to go every 15 minutes, to remind you to eat and drink regularly.
  5. A simple plan would be to eat a gel every 30 min (~200 cal per hour) and a bottle of sports drink per hour (100 cal per hour). Sip water throughout with the gel. You will need to take up to 10oz of water per gel.
  6. The products you use should also provide the following minerals/electrolytes, which will help you absorb your drink into your blood stream, and avoid cramping. Recommended sodium intake is 500-750mg/litre (33oz) – for example, one PowerGel has 200mg Sodium, 20mg Potassium, and 90mg Chloride. 1 litre (33oz) of Carbohydrate electrolyte drink has approximately 200-400mg of sodium.
  7. If the products you choose or those provided on the course do not supply the recommended amount of electrolyte you should consider using additional supplementation. As with all other products, you should practice their use in training prior to the race.
  8. 10 minutes prior to bike finish you should reduce your calorie intake and only take in sports drink or water. This allows your stomach to empty while still allowing your gut to absorb the food and fluid ingested earlier on the bike. You will be able to start the run in a relatively comfortable state. Once you start the run you can start consuming calories again according you your run nutrition plan.


  1. Wait 5-10 minutes into the run until your heart rate levels off before starting your nutrition/hydration regime.
  2. Often athletes’ heart rates are higher on the run than the bike. If this if the case, calorie consumption should be 15-30% lower per hour than on the bike.
  3. Many athletes find liquid calories easier to digest on the run, in the form of Carbohydrate electrolyte drink or cola. It is also common to eat PowerGels on the run.
  4. Follow a similar hydration protocol to the bike. Make sure that you get as much from the cup to your mouth as possible. Fold the paper cups to help control spilling.
  5. If you are running 7:30/mile, you will hit approximately 4 aid stations per hour, if they are spaced at 1 per mile. A goal is to drink 2 paper cups of liquid per aid station.
  6. If you are still running well, calories and drink taken with 1 mile to go will not impact your race, so you may skip the last aid station, with the exception of pouring some water on your head, or rinsing your mouth.

Nutrition for 70.3 deserves as much thought and planning as the rest of your ‘physical’ training.  You should develop a plan and practice it repeatedly in training to ensure that you finish the bike leg with energy left and set yourself up for a great run. Your nutrition plan is unique to you. It assumes that you have determined your own calorie requirements, and you know your digestive capabilities.

Lance Watson, LifeSport head coach, has trained a number of Ironman, Olympic and age-group Champions over the past 30 years. He enjoys coaching athletes of all levels. 

Contact Lance to tackle your first IRONMAN or to perform at a higher level.