The runner, compared to other athletes, has one more problem: the shock of impact with the ground. This very often has an impact on the digestive system and is essential to take into account both "before" and "during" a long and intense effort such as a marathon.
The week before the race, forget the myths that still reign in the amateur and non-amateur world, of the unloading and loading of carbohydrates. We’re now in the 2000s and what we thought was right in the 80s and 90s has since been contradicted several times by science where the research has come on in leaps and bounds.
The night before the marathon, you could fill up on pasta or rice as a first course as these are both examples of high glycemic carbohydrates, followed by a second course of a lean protein source such as chicken, fish or red meat. Add cooked or raw vegetables and then a portion of potatoes and a good drizzle of olive oil. At this point you will be sure to be full to the max. Having a rest will be more pleasant "with a full belly".
Upon waking, the next morning, you will still be quite full so you just need to top up the little amounts of muscle and liver glycogen consumed overnight. Many of your opponents will eat in relation to the distance of the race they are about to run - this is completely wrong and should be avoided!
You need to organise yourself depending on how long beforehand you should eat: if it’s 3 hours before the start of the race, you can have a meal, for example this could be 4 slices of wholemeal bread or 6 rice cakes with a protein source such as cooked ham (60/70g), 1 tablespoon of jam and some almonds. If you have as little as 2 hours before the start, you can have the same quality and type of food, but half the quantity, so you start the race so you start the race not feeling too full.
During the marathon, depending on your eating habits, you will have to eat foods which are easily digestable. I would definitely recommended having specialised foods such as isotonic gels or energy bars at regular intervals of 30/45 minutes but keep in mind, the complete strategy is always to try first in training more than once, in order to test your body’s reaction.
Hydration is of fundamental importance, so make sure you take full advantage of all the refreshments along the way to drink water and if the mineral salts you find are the ones you usually use, then alternate those along the race course.
After the race, pat yourself on the back and reward yourself for your performance: have a portion of carbohydrates with a high glycemic index and even some protein - a minimum portion size of 30g. You can use this moment to eat pasta, your favourite first course dish or a dessert, then a second portion of protein, or, if you prefer, a rapidly assimilated protein source such as isolated Whey powder proteins.
Iader Fabbri, Nutritional Consultant and Scientific Communicator