Marathon racer catching cup of waterAs an experienced endurance athlete, you’ll be aware that your nutrition plan can make or break your race. Perhaps you have had a bad experience recently? If you are new to endurance sport, you may be feeling overwhelmed by all the information available on race day nutrition strategies and wondering where to start. Whatever the situation you find yourself in, I hope that this blog will be of some help in making the best decisions for you. Fuelling during endurance events is very individual – what works well for your club mate may be a disaster for you – and it’s particularly important not to try anything new on race day. Use your longer training sessions as an opportunity to practise all aspects of fuelling and hydration until you feel confident that you have a plan that works for you. Of course, race day may throw up some unexpected challenges, such as higher temperatures than you anticipated or stomach problems related to race day intensity or distance that did not occur during training. First iron-distance triathlons are notorious for this! But having a nutrition plan and also being able to adjust it, for example by carrying alternative fuel sources and knowing what nutrition you will find at aid stations, are two of the keys to long distance racing success.

To review your current race day nutrition strategy or to create one for a new event, I suggest answering the following questions:

  • How long will it take me to complete the event? You will need to calculate your carbohydrate needs by the hour. Here’s a really useful guide from leading sports nutrition scientist Professor Asker Jeukendrup, based on the latest research.
  • What will my intensity be? The higher your expected intensity, the higher your carbohydrate needs per hour. If you are a slower athlete, I would suggest slightly less carbohydrate per hour than in the guidelines above, or you may encounter stomach issues. More carbohydrate than you need is also unlikely to result in you achieving a faster finish time. So, for example, if you are a mid or long distance triathlete who expects to spend the race at an average heart rate in zone 2 rather than zone 3, stick to 60g of carbs per hour rather than trying to ingest 90g per hour.
  • How metabolically efficient am I? This refers to your ability to burn fat at higher intensities. Athletes who have trained to delay the point at which they start to burn mostly carbohydrate rather than mostly fat will not require as much carbohydrate per hour, as they can rely on body fat stores for longer and consequently spare their muscle glycogen (carbohydrate) stores,. They may also choose to use fuel sources during the race that contain fat as well as carbohydrate, eg chia seed or nut butter based ‘gels’. See another blog of mine for more on the topic of metabolic efficiency and how to increase it.
  • How easily can I eat or drink while racing? This will have an influence on your fuelling choices. For example, an ultra-runner will be competing at a relatively low intensity which means that they are likely to be able to digest solid food while running or when stopped at feed stations. They are also likely to be carrying a Camelbak or similar fuelling/hydration system which enable them to carry 1-2 litres of fluid and some food. Whereas a marathon runner, running at a higher intensity, is likely to rely on gels or small bottles of sports drink that can be carried in a small pack around the waist. Or they may choose to rely on the sports nutrition products provided on the course. If this is the case, always practise with the product in question prior to the race to ensure you get on with it. A cyclist or triathlete will be able to carry nutrition and feed more easily on the bike than when running, so this presents a broader range of fuelling options, eg sports drink, gels, chews, bars, dried fruit, even sandwiches, homemade flapjacks or energy balls. A long distance open water swimmer will have to rely on the drinks, gels or food items made available at certain points in the race.
  • How will I carry my fuel? There are many options available. Runners are likely to choose fuel belts or Camelbaks. Cyclists have their jersey pockets as well on-bike storage options such as bottle cages and bags/boxes that sit on the top tube. Triathletes may make use of tri-suit pockets, tri-bar hydration systems and rear mounted bottles cages as well. Open water swimmers could carry a gel up their sleeve or even under their hat. If so, choose the type that is diluted with water to ensure that you can absorb it without needing to wash it down with water.
  • What nutrition is available on the course and do I know that it suits me? Always check the event website and email the race organisers if you can’t find the information you are looking for. Ask about availability of ‘real’ food like bananas and flapjacks as well as the sports nutrition brand (usually one of the race sponsors) and the exact products from their range that will be available on the course. Also check at what point on the course each aid station occurs so that you can build this into your nutrition and hydration plan. Then always practise using the available foods or products in training.
  • How good is my digestion during races? This is a whole topic in itself so if you know that gastro-intestinal distress in races is an issue for you, or you suffer from irritable bowel syndrome – which increases risk of problems in races – please see my blog on this whole topic, this should help you with your race fuel choices.
  • What is my back up fuelling plan? Things can go wrong in races….make sure that you are prepared for some of the more obvious things. Problem: you drop some of your nutrition. Answer: carry more than you need for your plan. Problem: you can’t stomach any more sugar. Answer: carry a savoury alternative like salted nuts or pretzels. Problem: the race is taking longer than you expected. Answer: allow for an extra hour or two, depending on the event, when planning your fuel needs. Problem: it’s hotter than expected. Answer: carry some electrolyte tablets or liquid that you can add to your water bottle if you are not already planning to use this.

The different choices available to fuel your endurance race and the difference between the various types of carbohydrate (eg glucose, fructose, maltodextrin, corn starch or isomaltulose) will be, in time, the subject of another blog post. But this summary may be useful. Bear in mind that you must check the serving size and carbohydrate content of individual brands and products as these vary considerably.


Type of product or food Approx g of carbohydrate per serving
Sports drink 20-30g per 500 ml (depending on dilution)
Energy gel 20-30g per sachet
Energy bar 30-40g per bar (bar size, protein & fat content vary considerably)
Electrolyte drink 0g per 500ml (don’t get caught out by this; electrolyte drinks do not contain sugars to provide fuel. They may have artificial sweetners)
Banana 25g per medium banana, 30g per large banana
Medjool dates 18g per date
Dried Apricots 5g per apricot
Raisins 24g per 30g (small handful)
Fruit Cake (eg Soreen) 22g per 33g slice

I hope the information in this blog helps you to put together a race day fuelling plan that works for you. For longer events of more than 3 hours’ duration, I suggest a combination of liquid and solid calories, together with some real food such as dried fruit if you able to digest it OK. And finally, don’t forget to plan your hydration needs. Using a sports drink covers both fuelling and hydration, of course, but you may struggle to meet your carbohydrate needs in longer events by using a sports drink alone – and your stomach may not thank you. For more information on hydration strategies which, like fuelling, are very individual, please see my blog post here.

Jo Scott-Dalgleish BSc (Hons) is a BANT Registered Nutritionist, writing and giving talks about nutrition for endurance sportBased in London, she also works as a Registered Nutritional Therapist, conducting onetoone consultations with triathletes, distance runners and cyclists to help them eat well, be healthy and perform better through the creation of an individual nutritional plan. To learn more about these consultations, please visit