How to Fuel a Marathon
Marathon fueling is tricky.
During training you can get away with minimal fueling during even your longest runs, since it is not best effort or for as long of a distance.
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It is easy to make the mistake of thinking you can/should get away with that fueling strategy during your marathon and that if you are going to fuel more during the event you can get away with not practicing.
Let’s take a look at what I suggest for marathon fueling.
There are a number of case studies of sorts that looked at what works for non elite and elite athletes during the marathon.
In 2013 researchers worked with a number of non-elites participating in the Copenhagen Marathon. Half of the runners used a freely chosen fueling strategy and the other half used a specific fueling plan of 60g carbs, 24ml water, a bit of caffeine and salt each hour.
The groups were matched by 10k time trial when sorted so they would have expected to have similar marathon times. However not surprising the freely chosen fuelers had an average time of 3:49 and the fuel scheduled runners had an average time of 3:38. It’s also important to note that gastrointestinal issues were not different for the two groups.
Even the elites follow this same basic strategy. Another fun case study looked at three elite Canadian marathoners and noted what their nutrition strategies were during the events.
They each consumed on average about 60g/240cal of carbohydrates and about 20oz of water hourly.
It’s important to note that all of the athletes in both events were using a carbohydrate mixture of glucose and maltodextrin. Doing this allows you to much more rapidly absorb the calories vs a pure glucose source.
Also while elites and non-elites do typically differ in their weights and race times the fueling strategies are similar. Elites typically can run the marathon at a higher percentage of their VO2 max so use more carbs vs fat during the event.
So, how do you do this during your marathon?
You may think this is a lot to take in, and if you’ve been habitually under fueling then it may feel like it at first.
The half marathon I recently ran had aid stations every 2-3 miles for the marathon, which is fairly frequent. 3-4 is a safe bet for just about every marathon you’ll run.
Elites have their own aid stations where they have their personal bottles at. They typically grab them on the go and down it over the next half mile before ditching the bottle. That’s why you rarely see elites holding bottles.
For us regular folk it is slightly more difficult. If you have an aid station every 3 miles and you’re running a 4 hour marathon that is 2 aid stations hourly. While you don’t want to slow down too much at every aid station, coming to a jog to grab 8-12oz of water and a gel will improve your time and decrease your chances of hitting the wall. Another option would be to carry a throwaway bottle with you for the first hour so you can skip the early aid stations.
I cannot stress enough the importance of practicing this during your long runs. Gels are the most often used in studies because they’re easy to track and use, but many runners also experience GI issues with gels. Taking them slower, such as half right way and then half a few minutes later and always with water can help. If you prefer fluid only calories or using something like gummies, use what works best for you!