Building up glycogen stores to improve endurance performance was developed as a sports nutrition technique in the 1960s. It is estimated to improve endurance performances of 90 minutes or more by 2-3%, which at first glance may not seem much, but is nonetheless substantial and also dependant on the length of the competition.

The reason for the increase in performance lies in the fact that it delays the time at which the glycogen stores start diminishing and force the muscles to switch to fat burning instead. This dreaded moment, known as “hitting the wall” when you are 30 km into a marathon, for example, entails a sudden slump in performance and is experienced by most runners once in their sporting life.

In its original form (called the Swedish or Saltin diet), carbo-loading consisted of two phases, namely a phase of 3 to 4 days where you empty your carbohydrate tank (and eat a higher amount of fat at the same time) and an equally long loading phase. The entire week prior to the competition was therefore required for this. These days, however, the arduous, specific emptying phase is dispensed with. The most common modified method involves eating a diet that is extremely rich in carbohydrates during the last three to four days before the competition with a heavy reduction in training at the same time. The reduction in training is an important part of carbo-loading. If at all, the training should only be very relaxed and short to ensure the stored muscle glycogen is not burned up in training again. During carbo-loading, you also need to make sure you drink sufficiently high amounts of fluids. 

Not very easy to do

What at first glance appears to be relatively simple, is really quite difficult in practice. This is because the recommendation for the intake of carbohydrates during the competition preparation phase states that 70% of the energy absorbed should be in the form of carbohydrates. A percentage value is not only very difficult for athletes to interpret, but there is still no guarantee that it will really fill the glycogen stores. 

It is better to use absolute values in grams. These correspond to one kilogram of body weight per day. For efficient carbo-loading during 1 to 4 days, values between 7 and 12 grams of carbohydrates per kilogram of body weight per day are recommended. For a 70-kg man, this means that he needs to eat around 500 to 850 grams of pure carbohydrates per day. This amount corresponds to approximately 7-10 plates of spaghetti, an amount that even great pasta lovers would barely be able to manage! Studies of marathon runners have shown that these theoretical recommendations are in fact extremely difficult to implement. Even runners who deliberately do carbo-loading usually only achieve half the recommended 7 grams of carbohydrates per kg of body weight. 

Pasta alone is not enough

So, what do you need to eat or drink to achieve the desired amount of carbohydrates? While many athletes know and use the classic sources of carbohydrates such as pasta, bread, and rice, they don’t consider fruit juices, low-fat confectionery, sugar, and honey to be supplementary food and underestimate their importance in carbo-loading.

The fact that a litre of cola or another commercial sweet drink, for example, contains as many carbohydrates as a big plate of spaghetti, illustrates this fact. Therefore, the meal plan during carbo-loading can and should explicitly include sweet drinks, fruit juices, sports drinks, toast bread with lots of honey and jam as well as gummy bears, and Basler Läckerli biscuits or also dried bananas and figs. During carbo-loading, any reservations about eating these foods can be thrown out the window, if you can tolerate them, that is (an excess of gummy bears can also upset your stomach…). In other words: everything that is not too fatty, but contains a lot of carbohydrates, is exactly right. And don't be afraid, as any excess calories consumed within this short period of time will not have a negative impact on your weight.

The following also applies: whole grain products, vegetables, raw fruit and vegetables and salad, which provide essential nutrients such as valuable vitamins, minerals, and fibre, may be omitted with a good conscience for three days before a competition. The reason: carbo-loading is not predominantly about health aspects, but about optimising performance. And due to their satiating effect, wholemeal bread or vegetables ensure that you are already full after a mixed salad and a plate of pasta before achieving the necessary amount of carbohydrates. 

Total amount is decisive

Whether the carbohydrates consumed during the three to four days of carbo-loading are complex, such as starch, or simple, such as confectionery and drinks is not so important. The main thing here is that you can achieve the required quantity without any digestive problems. This means: eat as much as you want! The consequence of this: after doing proper carbo-loading, many athletes can no longer stand the sight of pasta and sweet drinks and can hardly wait to eat a fat sausage or salty chips after the competition - bon appetit!

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