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Marathon During-Fuelling

The body can only store around 1600Kcal of carbohydrates in the body and you re likely to burn over 2000Kcal during the marathon which means you will need to fuel during the race. But what are the best during race fuelling strategies.

Your primary fuel source during the marathon will be carbohydrates. However, we only store a limited amount of carbohydrates even with a good carb-loading strategy. Therefore, you will need to fuel during the race. The current recommendation is any exercise longer than 90 minutes requires 90g of carbohydrates per hour of exercise. To give you perspective that’s roughly a bowl of pasta per hour of running. Which means the average marathon runner (assuming a time of 4.5 hours) would require around 400g of carbohydrates (the equivalent to about 1600Kcal).

Consuming 1600Kcal during marathon would be a very difficult task and may not benefit you. So you need to make sure your body can get the most from each gram of carbohydrates you give it, so how do you do this?

Training itself at both a low an high intensity overtime will improve your bodies glycogen sensitivity which means you will become better can absorbing and utilising carbohydrates. Which means keep consistent with training and your body will get better a using less carbohydrates for the same intensity.

Further, the motion of running does not lend itself to fuelling without feeling discomfort. Which unfortunately means you are going to need to practice in training how to fuel/get used to the feeling. For example, one strategy is going for an immediately after eating a meal, although this should be done with caution, so start with smaller meals.

When practicing your fuelling you also need to consider the type of fuel. Although we need to get carbohydrates in the body there are many different forms we can get this (gel, drink solid food etc.). Experiment with different fuel types to see what works for you. However, try and focus on gel or liquid form quick release carbohydrates.

A big mistake runners often make is waiting till they feel dehydrated or in need of fuel during race. But by that point it’s too late, you should be feeling little and often throughout the race to prevent this feeling.

So definitively how much should you eat? Although it will vary from person to person but roughly aim for 7g/kg of body weight. So for example if you are 63kg you will need 441Kcal of carbohydrates which is a total of 110g of carbohydrates or 28g per 10km of running.

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