Knowledge Base > Physiology and Metrics

Carbohydrate Stores

Besides fats, carbohydrates are the most important source of energy in cycling and triathlon. The higher the intensity, the more energy is obtained from carbohydrates and the more important is the size and quantity of your carbohydrate stores.

Carbohydrates are consumed at any intensity in order to provide energy in the working muscles (see metabolic model). As performance increases, carbohydrate consumption increases exponentially. If you do not supply exogenous carbohydrates (e.g. gels, drinks) your carbohydrate stores will be emptied over time and the energy supply, thus also the performance, will decrease. You will never be able to completely empty your carbohydrate stores, because the body does not release all autonomous and vital reserves. Empty glycogen stores manifest themselves, for example, in hitting the wall and mean a very clear drop in performance. Thus, glycogen stores and carbohydrate availability are probably the biggest limiting factor during longer and constant endurance efforts.

Almost all of your carbohydrate reserves are stored in the form of glycogen (the storage form of carbohydrates) in the working muscles and liver. Knowing the size of your glycogen stores and your individual carbohydrate consumption is essential for optimizing nutrition and pacing strategies in training and competition.

Good to know Glycogen cannot be transported back and forth between muscles. The amount of glycogen available in the working muscles (in cycling, those of the lower extremities) is crucial.