You will undoubtedly have heard of carbohydrate stacking, aka carboloading. What exactly is it and when does it make sense to do it? In this article, we’ll go over the do’s and don’ts.
At low intensity, a well-trained endurance athlete can generate his or her energy needs mostly from fats. However, even at low intensity, part of the energy will always come from carbohydrates and this proportion increases as the intensity increases. These carbohydrates are the primary source of energy at high intensity. How long you can sustain this high intensity depends mainly on the amount of carbohydrates stored in the body. So it sounds logical to make sure this supply is as large as possible before you line up at the starting gun.
Your body can at most store about 600 to 750 grams of carbohydrates. These carbohydrates are stored in the liver and the muscles in the form of glycogen. This amount can be used for a maximum of 90 minutes at full throttle (or FTP) and then that tank will have been emptied. So for most cycling activities, just making sure your stores are full at departure is not enough. You will also need to try to keep replenishing the carbohydrates supplies while cycling.
In the old days, the tried and true method was to first completely deplete the storage by training hard and eating as little carbohydrate as possible for a week beforehand, and then replenish that storage completely in the last few days before the event. We now know that the storage can be replenished to the same level without first going though that depletion phase. The only thing you need to do is to reduce the training load considerably in the last few days and increase the carbohydrate intake.
The reduction of training load is called “tapering“. It ensures that you are well rested for the “moment suprême”. Because you’ll also miss some training, you don’t want to make this period too long or your form will begin to fade. How long is very personal. Some people feel better with five days of very calm training, while others only need one or two rest days to feel fresh and well-rested again.
To ensure that the maximum capacity in the muscles and liver is used for glycogen storage, consumption of 8 to 10 grams of carbohydrates per day is recommended in the 24 hours before the event. For many cyclists this is not much more than their normal, daily intake. Especially in the Western world we already eat quite a lot of bread and pasta. A common mistake is to pile a lot more additional carbohydrates on top of that. Because once the glycogen stores are full, the additional carbs are stored as fat and that’s of little use to you as a cyclist.
What you should keep in mind is that every gram of stored carbohydrate is accompanied by 3 grams of water. So with a full tank of carbohydrates you also drag along up to 2 liters of water. Therefore, stacking carbohydrates really only makes sense for very long, hard efforts and has little benefit for a shorter race or time trial.
Eating too much.
Another common mistake is to eat huge amounts of carbohydrates on the day itself. The night before D-day, the carbohydrate stacking should have been completed, but don’t go crazy at the evening’s pasta buffet. On the morning of the ride, a ‘normal’ breakfast with about 60 to 90 grams of carbs should be sufficient. Make sure you have eaten up to about 2 hours before the start and avoid fats and proteins in the morning. These overload the digestive system. You can take a sports drink (energy drink or carboloader) with around 40 grams of carbohydrates in the two hours before departure, but more is really not necessary. Wolfing down a huge stack of pancakes close to the start actually puts you out of contention before the race has even started!
Eat a variety of foods.
Finally, it is very important to stack carbohydrates in a varied way. After all, you absorb carbohydrates the best when they come from different sources and in many different forms. Especially the slower carbohydrates that your body absorbs more slowly, such as brown rice, spelt pasta and whole grain bread, are recommended as they can be transferred more easily into glycogen.