Fueling the Distance: Mastering Intra-Run Nutrition for Peak Marathon Performance

With about a month to go until the London Marathon, runners are fine-tuning their preparations, focusing on everything from tapering and rest to the crucial aspect of intra-run nutrition. 

“At big championships, it’s not the fastest person, it’s the person who gets it right on the day.” – Paula Radcliffe.

Running a marathon is not just a test of physical fitness; it’s a comprehensive challenge that demands attention to health, a healthy diet, consistent exercise and pulling it all together on the big day. To tackle this endurance feat successfully, focusing on intra-run nutrition becomes paramount. Proper nutrition during a marathon can significantly influence your energy levels, performance, and overall experience.

Nutrition industry experts generally offer several key pieces of advice when it comes to intra-race fuelling, typically around carbohydrate intake, timings and hydration. 

Here are our 6 top tips to ensure you maintain your stride and vitality throughout the 26.2 miles/ 42km.

Note, this is not only applicable on race day but also for your longer runs. Treat these as test runs for the big day. It’s important to give this ago ahead of time, so you know what works for you!

1. Understand Your Needs

The first step in planning your intra-run nutrition is understanding your body’s needs. During a marathon, your body primarily burns carbohydrates for fuel. However, your muscle glycogen stores, the primary source of carbohydrates, are limited and can become depleted throughout the race.

To prevent “hitting the wall,” a term used to describe the point at which a runner runs out of glycogen, it’s essential to replenish these stores by consuming carbohydrates during the run.

2. Start Early and Be Consistent

Don’t wait until you’re feeling tired or hungry to start fueling. By that time, your tank will be nearly empty, and once you hit empty it is very hard to recover. Begin consuming carbohydrates early in the race, ideally within the first 30-45 minutes, and continue at regular intervals.

First, establish the duration of your event – how long do you think your marathon will take you? That will largely determine the amount of carbohydrates you need. A common recommendation, however, is to ingest 30-60 grams of carbohydrates per hour (Jeukendrup, 2011, 2014). 

Note, however, that it is likely best to try to take on a little bit of fuel every 15 minutes. Not only will this help to keep your energy levels steady, but it will help limit any GI stress.  Some runners find that when they add in too much fuel—like an entire gel at one time—their digestive system is upset.

This can vary based on individual tolerance and needs, so it’s essential to practice your nutrition strategy during long training runs to find what works best for you.

3. Choose Easily Digestible Foods

When selecting foods or products for intra-run nutrition, opt for those that are easily digestible to minimise the risk of gastrointestinal distress, which is a common issue for marathon runners.

Energy gels, chews, and sports drinks are popular choices as they are designed to be absorbed quickly and provide a rapid source of energy. These products often contain a blend of glucose and fructose to maximise carbohydrate absorption and utilisation.

Try to avoid relying on what the race offers, and pack your own fuel – fuel you have tested and run with before. Always take a little more than you need, just in case. For any nutrition geeks, Asker Jeukendrup is your man – with 30 years of sports nutrition experience under his belt, he’s put together a tonne of useful and easy-to-understand info here.

4. Stay Hydrated

Hydration is an integral part of your nutrition strategy. Dehydration by as little as 2% of body weight can impair your performance (Cheuvront and Kenefick, 2014). 

Given the London Marathon is in April, chances are that the vast majority of your training will have been carried out in the chilly winter months. However, the end of April can see some sunny spring days, which are far warmer than you are used to. 2018 was a key example of this, as runners experienced temperatures of 24.1C – the hottest on record for the race!

Don’t get caught out by this and ensure you sip fluid at regular intervals throughout the race.

5. Practice Makes Perfect

Every runner’s body is different, so what works for one person may not work for another. It’s crucial to experiment with different types and timings of nutrition during your training runs. This not only helps you understand what your stomach can tolerate but also allows you to refine your strategy based on how your body responds.

It is also likely worth ‘training your gut’ in the lead-up (Jeukendrup, 2017; Cox et al. 2010).  This is a technique used to get your digestive system used to take on fuel and fluid during your sessions. This typically involves trying things like training with large volumes of fluid, training straight after a meal and training with relatively high carbohydrate intake during exercise. All of which over time, have the benefit of reduced GI symptoms and consequently enhanced performance.  

Never introduce new things on race day, as this may have an unwanted (and potentially uncomfortable) effect!

6. Be Flexible and Listen to Your Body

Despite having a well-planned nutrition strategy, it’s essential to be flexible and listen to your body on race day. Various factors, such as weather conditions and how you’re feeling, can affect your nutritional needs. If you find yourself struggling with energy levels or gastrointestinal discomfort, be prepared to adjust your plan accordingly. Don’t let this throw you off course!

In conclusion, mastering intra-run nutrition is a key component to a successful marathon experience. By understanding your body’s needs, starting early, choosing easily digestible foods, staying hydrated, practising your nutrition strategy, and being flexible, you can maintain energy levels, avoid common pitfalls, and achieve your marathon goals. 

Remember, the foundation of a great race is laid long before you toe the start line, with each training run providing an opportunity to refine your approach to intra-run nutrition.

Good luck!

If you would like to discuss your goals or any potential nutrition changes to support your training in the lead-up to the London Marathon, book a call with us.

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  1. Jeukendrup, A.E., 2011. Nutrition for endurance sports: marathon, triathlon, and road cycling. Journal of Sports Sciences, 29(Suppl 1), pp.S91-S99.
  2. Jeukendrup, A., 2014. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 44(Suppl 1), pp.25-33.
  3. Cheuvront, S.N. and Kenefick, R.W., 2014. Dehydration: physiology, assessment, and performance effects. Comprehensive Physiology, 4, pp.257-285.
  4. Jeukendrup, A.E., 2017. Training the gut for athletes. Sports Medicine.
  5. Cox, G.R., Clark, S.A., Cox, A.J., Halson, S.L., Hargreaves, M., Hawley, J.A., Jeacocke, N., Snow, R.J., Yeo, W.K. and Burke, L.M., 2010. Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. Journal of Applied Physiology, 109(1), pp.126-134. DOI: 10.1152/japplphysiol.00950.2009
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Published by Georgia Chilton

In her teenage years, a love of food and rowing led Georgia into this field as she wanted to know how to optimise performance through nutrition. With a BSc in Nutrition and an MSc in Sports and Exercise Nutrition, she has the skill set to help you track towards your goals and maximise your potential.

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