Race Nutrition

This article shows you how to get your race-day nutrition right and increase your chances of having a good race. 

Nutrition for IRONMAN and Endurance Events

During IRONMAN Races and Endurance Events, you’ll burn four times more calories per hour than usual. Despite burning so many calories, you’ll barely feel like eating or drinking in the latter stages of the race. This is why you need to plan your nutrition carefully.

The energy you need for endurance events comes from a ratio of 65% carbohydrate and 35% fat. Thankfully we all have enough fat in our bodies, so we don’t need to consume any more during the race. However, our carbohydrate stores will run out after around 90-120 minutes.

To keep you energised and healthy, you need to consume carbohydrates, water and salt (arguably). The more palatable your nutrition choices, the more you’ll be able to consume.

There is a new type of carbohydrate product from the Swedish company Maurten (we have no ties to them). The world’s top marathon runners use Maurten products, often without sponsorship.

For endurance athletes, Maurten gels and drinks are potentially game-changing. They enable you to ingest more carbohydrates with less risk of getting jelly belly and other forms of gastrointestinal distress. A small bottle of Maurten 320 Drink Mix contains 80 grams of carbohydrate, which is the equivalent of four energy gels.

However, as with all energy products, it’s important that you use them regularly in training first. For example, Maurten energy gels are thick and can be hard to swallow sometimes. They may not suit you.

After working with over 10,000 athletes here’s how we recommend you prepare for your event. For endurance triathlon, running or cycling. Choose the sections relevant to your chosen event.

Swim Nutrition 

It’s not practical to consume gels or drinks during an IRONMAN swim, so don’t bother. Just make sure you’re fuelled up beforehand. We cover that in detail in the “Race Day Nutrition Plan” section below.

Bike Nutrition

It is easiest to take on nutrition on the bike because you can carry bottles, bars and gels. Your upper body is static, which makes it easier to consume food and drink on the move. Think of it as a buffet on wheels. We’ll explain how much to consume later, but for now, here’s what to carry.

• OPTION 1: Water for hydration, carbo-chews such as Clif BLOKS Energy Chews for carbohydrates. SaltStick capsules for extra salt, depending on your sweat rate.
• OPTION 2: Maurten 320 Drink Mix and nothing else. This drink is easiest on your gut, so you’ll absorb more carbohydrates. It also takes care of your hydration needs. If it’s a hot day and you’re sweating lots, consider using Maurten 160 Drink mix instead. This is the same product, but half as strong, so there’s more water to quench your thirst. Maurten drinks do contain some salt, but not that much. On hot days you may need to supplement this with SaltStick capsules (or similar).

Run Nutrition

For IRONMAN athletes by the time you get to the run, your gut will be compromised, and you need to treat it kindly. It can be the same for marathon runners; this is where people struggle. It is common to get jelly belly, cramps and diarrhoea – or just feeling plain exhausted. Your nutritional strategy can help.

• Energy drinks, ideally, with a 6-10% concentration of carbohydrate, so your gut can cope.
• Avoid energy gels and bars. Their carbohydrate is very concentrated and can cause gastrointestinal distress at this stage of your race.
• If you can’t cope with energy drinks, regularly sip Coke instead. It is like pure sugar and starts entering your bloodstream before it even reaches your stomach. Consume anything else you feel like – small bits of fruit often work well when you’re feeling lousy.

IRONMAN and Endurance Events: Race Day Nutrition Plan

Before your endurance race, you should make a detailed hour by hour nutrition plan. It can be a time-consuming exercise, but it’s totally worthwhile. You don’t have to memorise it perfectly, but it’s still better than making it up on the day.

Below, we list how many grams of carbohydrate per kilogram of your bodyweight you’ll need to consume pre-race, according to IRONMAN University.

You will also see the recommended total carbohydrate, fluids and sodium intakes per hour, that you will need during your race to sustain your energy, hydration and electrolyte balance throughout.

We’ve written mostly in metric units. If you use US ounces, see the calculators below.

• You can calculate grams to US ounces here.
• You can calculate kilograms to pounds here.

You’ll need to study the nutritional information on packets, and stick with products that are mostly carbohydrate. Avoid fibrous foods like corn or broccoli. Normally they are fine, but can cause stomach upset during a race.

Race Day Breakfast

Do your best here. Whatever you plan for race-day - be sure to have practised in training. As you can hear from the pro's, everyone is different!

What's Your Pre-Race Breakfast? | GTN Ask The Pros

Choose volumes according to how much time you have pre-race:

If you choose to eat your breakfast 4 hours pre-race:

• Carbohydrate: 4 grams per kg (bodyweight). If you weigh 70kg = 280 grams of carbs.
• Fluid: 5–7 ml/kg. If you weigh 70kg = 350-490 ml.
• Sodium and Electrolyte: Consume 450–1120 mg (according to sweat rate) of sodium per litre from a sports drink, salt capsules or small amounts of salty food to stimulate thirst and retain consumed fluids.

OR If you choose to eat your breakfast 3 hours pre-race:

• Carbohydrate: 3 grams per kg (bodyweight). If you weigh 70kg = 210 grams of carbs.
• Fluid: 4–6 ml/kg. If you weigh 70kg = 280-420 ml.
• Sodium: Consume 450–1120 mg (according to sweat rate) of sodium per litre from a sports drink, salt capsules or small amounts of salty food to stimulate thirst and retain consumed fluids.

OR If you choose to eat your breakfast 2 hours pre-race:

• Carbohydrate: 2 grams per kg (bodyweight) . If you weigh 70kg = 140 grams of carbs.
• Fluid: 3–5 ml/kg. If you weigh 70kg = 210-350 ml.
• Sodium: Consume 450–1120 mg (according to sweat rate) of sodium per litre from a sports drink, salt capsules or small amounts of salty food to stimulate thirst and retain consumed fluids.

OR If you choose to eat your breakfast 1 hour pre-race:

• Carbohydrate: 1 gram per kg (bodyweight). If you weigh 70kgs = 70 grams of carbs.
• Fluid: 2–4 ml/kg. If you weigh 70kg = 140-280 ml.
• Sodium: Consume 450–1120 mg (according to sweat rate) of sodium per litre from a sports drink, salt capsules or small amounts of salty food to stimulate thirst and retain consumed fluids.

Just before start:

• Carbohydrate: 5–30 grams, 5-30 minutes before. For example, a half or full energy gel, or a few swallows of energy drink.
• Fluid:  Ad-lib, to thirst.

During the bike:

• Carbohydrate: 60-70 grams of carbohydrate per hour. Some athletes may tolerate up to 90 grams. For example, six Clif Shot Blocks or 2/3 of a bottle of Maurten 320 every hour.
• Fluid: Maximum absorption is usually 1–1.2 litres per hour (32 to 40 fl. oz.) Depending on your sweat rate.
• Sodium: 500-700 mg/litre of fluid (32 fl. oz.). Salty sweaters: up to 1,000 mg/litre (32 fl. oz.)

During the run:

• Carbohydrate: 40-50 grams of carbohydrate per hour. Little and often. For a standalone marathon, you may be able to tolerate up to 60 grams of carbohydrate per hour.
• Fluid: Drink to thirst or dehydration level, sip little and often.
• Sodium: 500-700 mg per litre of fluid (32 fl. oz.). Salty Sweaters: up to 1,000 mg/Litre (or 32 fl. Oz)

Races and Events less than 3 hours: Race Day Nutrition Plan

For all events, you can follow the breakfast and pre-start guidelines from above.

Less than 60 min

• You will have then have enough energy to fuel your race.

60 - 90 min

• Carbohydrate: 20-30 grams of carbohydrate in the form of a gel or sports drink at 60 mins can give you a boost for the finish.
• Fluid: Drink to thirst or dehydration level, sip little and often.
• Sodium: 500-700 mg per litre of fluid (32 fl. oz.). Salty Sweaters: up to 1,000 mg/Litre (32 fl. oz.).

90 min - 3hrs

• Carbohydrates: 50-70 grams of carbohydrate per hour. Little and often. For example, from Clif Shot Blocks, gels or sports drink.
• Fluid: Drink to thirst or dehydration level, sip little and often.
• Sodium: 500-700 mg per litre of fluid (32 fl. oz.). Salty Sweaters: up to 1,000 mg/Litre (32 fl. oz.).

More Nutrition Choices

Energy Gels, Bars, 'Real' Food and Drinks

There's nothing magic about energy drinks, bars and gels, their main ingredients are carbohydrates and water, and you can normally make your own, homemade versions. However, they do offer a convenient and well-packaged way to stay fuelled during a race.

1. Energy Gels - A sweet gel in a convenient packet, typically containing 100 calories and 22 grams of carbohydrate. Some contain salts, vitamins and caffeine, although the carbohydrate is the important bit. Gels labelled “isotonic” are more watery and easier to consume with a dry mouth but contain less carbohydrate per gram. Caffeine gels often taste bitter, but there are proven performance gains to be had.
2. Energy Drinks - Powdered or pre-made drinks containing predominantly water and carbohydrate. Some contain electrolytes (salts), vitamins, caffeine and even protein. Remember that on race day your primary requirements are water and carbohydrate and for long races in hot climates electrolytes are beneficial. Choose a sports drink with 6-8% carbohydrate for rapid absorption.
3. Energy Chews - These are simply chewy sweets or jelly blocks containing mostly carbohydrate. They are often more palatable than energy gels and don’t leave you with such sticky fingers. Clif Shot Bloks are a good example; one pack contains six blocks - 48g carbohydrate.
4. Energy Bars - These are dense pre-packaged cereal bars, containing mainly carbohydrate. They are useful on race morning or while training. They can be more difficult to digest during racing, and there is a wide variety offering different contents. Be sure to read the labels and practice during training if you are thinking of using them during your race or event. 
5. Real Food - For some, fuelling from processed food is not ideal. If choosing to consume real food during exercise, you will need to experiment and pay attention to the nutritional content. You need to find easily digestible carbohydrate-rich foods that work to provide your energy requirements and are practical for consumption on the move. Real food provides a slower release of calories than processed fuels, you, therefore, need to be on top of your food intake and eat before feeling hungry. Practice in training is essential (at race pace if possible).
6. Recovery Drinks - The main ingredients in a recovery drink are carbohydrate and protein. Some also contain fat, electrolytes and vitamins. Research indicates that the optimal ratio for a post-endurance recovery drink is four parts carbohydrate and one part protein. Interestingly, plain milk contains a similar ratio. These drinks are convenient when you don't have a chance to eat immediately after a tough workout.
7. Recovery Bars - These are tasty bars containing a mix of carbohydrate, fat and protein. These often taste as good as chocolate bars like Snickers and Mars, so it’s tempting to eat lots. Eating foods like these straight after exercise is shown to heighten recovery, although you could get the same effect from a homemade smoothie for example. Just be careful to eat according to your training volume. 

Key Considerations

• If you have pre-existing health factors, you may need to make adjustments to your nutrition plan.
• Some conditions and dietary restrictions require consultation from doctors or nutritionists.
• Obtain the many essential vitamins and minerals from a varied and balanced diet.
• Your energy needs are determined by your resting metabolic rate and daily activity level.
• Your hydration plan should take into consideration your sweat rate and climate.
• Replenishing fluids and electrolytes can prevent dehydration and hyponatremia.
• Post-race nutrition helps replenish the body, restore muscle, replace fluids and sodium lost to sweat and respiration and provides the nutrients needed for muscle repair.
• If you are planning to use on-course nutrition products, you should use these products during all training sessions in preparation for race day.

Final Tips On Race Nutrition

Mike Tyson once said that “everyone has a plan until they get punched in the mouth”. Well, that’s how it works during endurance events too. While it’s important to make a pre-race nutrition plan, you must be prepared to adapt it along the way. You can never predict how your body will react on race day.

It can be hard to consume much before a race, but it helps if you sip a sports drink in addition to your breakfast. During the race, the secret is to refuel little and often. We recommend setting a countdown alarm to sound every 10-minutes as a reminder to eat and drink.

Finally, make sure you practice your nutrition in training. Evidence suggests that the gut is trainable – in other words, you can improve your ability to digest carbohydrates on race day.

Taking the time to work out your nutritional requirements for a race can be a time-consuming exercise, but it's totally worthwhile. You invest a lot of time training to be physically ready for your race. Don't waste this hard work and put your race in jeopardy by being unprepared and unable to fuel your way to success.

For more information, check out Phil's blog posts:

Triathlon Nutrition 101

The Essential Ironman Nutrition Guide

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