How to fuel an Ultra marathon

Nutrition is an integral part of performance. Most runners on a marathon start line will know of the importance of carbohydrate loading ahead of the event and most will have practiced with gels, carbohydrate drinks or chews, aiming for around 60-90g of carbs per hour for distances taking over 2 hours, to prevent their glycogen stores from depleting completely and hitting the wall. 

While running has always been popular, until recently, the peak distance most runners would work up towards would be the 26.2 miles of the marathon. However in the last decade we have seen ultra distance running events spring onto the scene and now there are so many opportunities to not only go beyond the marathon distance but there are also running events and races over many different terrains from road, desert, trail, mountains and altitude. 

Fuelling beyond the marathon – is it really that different? 

In general, the basics of sports nutrition still stand. For events that are going to take over 2 hours to complete, it is recommended that you aim for 60-90g of carbs per hour. However, how you take this can vary depending on the terrain you are running on. It is important to remember that running on road is likely to be a lot faster than running on sand or altitude or even over technical ground. So while a 50km run may not seem that much further than a marathon, times will vary significantly even if the perceived effort over the distance is the same. 

Everyone will have their own personal preference when it comes to race day nutrition. It will also depend on the type of race – supported, unsupported; at altitude or in the desert; hot or cold; road or trails; single day or multi day and how long each day will be.

That said, ideally fuel needs to be in the form of glucose and fructose; key fact, the body can absorb around 60g of glucose per hour and 30g of fructose. There are some new studies emerging that suggest that this upper limit of 90g in total, could be increased to 120g in some athletes who train their guts but presently the sample sizes used have been small and only done in men running at altitude, so for now until we have more robust studies, I tend to recommend sticking to an upper limit of 90g of carbs per hour. 

However, what we do know is that during these longer events, especially if the terrain is undulating and constantly changing, there is more of an opportunity to use real food options. 

The longer the duration of the run, the more beneficial it can be to include some real food options as relying on gels and carbohydrate drinks alone for hours on end can lead to taste fatigue, meaning you may start to avoid taking on nutrition which will impact performance. 

Some common mistakes that I see regularly include:

• Leaving it too long before they start fuelling; ideally you want to start taking on nutrition within the first 30 minutes and continue every 30-40 minutes.
• Taking energy gels too quickly; aim to take one gel over 4-5 minutes rather than all in one go. This helps with absorption and also tolerance.
• Becoming dehydrated and not taking on replacing fluids and electrolytes, specifically sodium.

Real food options will also vary from individual to individual. Some will prefer savory options like marmite and cheese bagels or sandwiches, others may choose foods like pizza, banana, hot cross buns and I’ve even known athletes who want sushi.

While carbohydrate is still the primary focus, sodium intake, caffeine timing and more recently, even protein intake will all play a part. 

Sodium intake – how much should you take?

Sodium losses are very individual but what we do know is that for ultra distance events, it is useful to start with a ballpark of around 700-900mg of sodium per litre of fluid. While this is a good place to start, some people may need a bit less and others a bit more. This is something you will need to work out for yourself and also be aware that the conditions of the event will also need to be considered – cold regions versus hot versus humid or even temperate. Women may also be a bit more mindful depending on where they are in their menstrual cycle. 

How does protein play a part?

A relatively new recommendation that has been specifically suggested for ultra distance events, especially those spanning over 6 hours and on very technical ground, is the inclusion of a small dose of protein. The recommendation is 5-10g of protein every 1-2 hours. While getting in the carbohydrates is relatively easy, finding good sources of transportable protein is slightly more tricky. This is where the new SiS Oat bar really comes into its own. With 40g of carbohydrate and 10g of protein, it is the perfect choice to include in your running pack. 

Whatever you choose, the key is practice, practice, practice until you have nailed what works for you.