You can read a ton of books about endurance, ask a million friend or shop assistance, but you wouldn’t get any real answer. What should you eat while making an endurance effort? I remember Dean Karnazes telling about a pineapple pizza, but I wouldn’t consider it as an advice.

We finally asked to a biochemistry expert.

Movimentore: We usually run 50k or cycle 200k on Sunday mornings, sometimes we feel a little sluggish in the middle, is that ok?

Expert: Well, during training or long endurance runs I’d consider compulsory a good “fuel” integration in order to provide the necessary energy to the muscles.

M: So what should we eat?

E: The real “fuel” for muscles are carbohydrates. It’s important to reintegrate carbohydrates during the activity, there are a number of reasons. They help to stabilize glycemic levels, especially during prolonged effort, avoiding energy drops. They also decrease the tiredness perception during the activity. Finally, they allow to have a lower consumption of the glycogen reserve.

M: Fine, but I never saw “carbohydrates” on the shelves…

E: In general sport supplements (such as energy drinks, gels and bars) are a good source of ready-to-use energy. They contain carbohydrate besides electrolytes, vitamins and sometimes proteins that help the athlete to improve its performance. But the questions are: which is the best source of carbohydrates? maltodextrins or simple sugars (glucose, fructose)?

Maltodextrina molecular structure

M: Ok, let’s go back from the start: what are maltodextrins?

E: Maltodextrins differ from glucose and fructose, because they are complex carbohydrates obtained by the hydrolysis of corn starch or other sources (potatoes or rice). You can image them as many glucose molecules (from 3 to 17) that build-up a long and organized chains or simpler as pearls that make up a necklace. Despite their definition as “complex carbohydrates” maltodextrins are rapidly adsorbed and converted in source of energy, moreover they display numerous advantages that make them suitable as sport supplements:

  • They contains approximately 4 calories per gram
  • They are cold-water soluble (I don’t think you would like to drink hot water while doing your run)
  • They have low or no flavor nor sweetness

M: They have better features, but why should we prefer complex carbohydrates instead of simple sugars?

E: The biggest advantage of maltodextrins compared to simple sugars is their high digestibility, that lead to a small recall of blood in the intestine thus leaving a larger blood affluence to the muscles leading to a more efficient sport performance. Moreover, while the consumption of simple sugars causes the recall of water in the intestinal lumen that lead to annoying intestinal disturbs (like spasm, nausea, vomiting and diarrhea), in maltodextrins this collateral effects completely lack thanks to their chemical properties. Due to this high digestibility, maltodextrins are used also after the performance in order to reintegrate the energy lost.

M: What’s the advisable intake?

Suggested dosage vary as function of the length of the performance, as in the table below.

Performance length       Suggested dosage

30-60′.                                Small amounts

1/2h.                                     30 gr/h

2/3h.                                     60 gr/h

>3h                                        90 gr/h

To make a long story short, maltodextrins can be used before, during and after the performance. For both energetic and hydration purposes, you can take them in a cold drink with a concentration of 5-8%. Possibly, their assumption has to be paired with sodium and electrolytes in order to replenish the amount lost during the activity.

M: Thank you, you’re a real expert!

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