The 3 energy systems

The Basics

These are the 3 Energy Systems that keep us moving:

• ATP-PC System – Uses ATP and PC from muscles. Supply energy very quickly because oxygen is not needed for the process. No lactic acid is produced.

• Anaerobic Glycolysis/Lactic - Uses carbohydrates (glucose) stored in the muscles as Glycogen. Because no oxygen is required, energy is produced quickly. Lactic acid is produced as an end product.

• Aerobic System – This system uses carbohydrates (glucose/glycogen) and fats to generate energy. Because oxygen is required for the process, energy production takes a little longer but can continue for a much longer duration (in theory forever!). No lactic acid is produced.

Figure 1 illustrates the duration of each event and which energy system is mainly required.

However..

It does not mean that when your sprinting you will use 100% of ATP-CP system, or when you are running you will be 100% at Aerobic System. There is an overlapping between them during an activity (figure 2).

The body stores a limited amount of ATP, so the three energy systems work together to provide the energy to keep moving. The extent to which each one is engaged varies depending on the duration and type of activity.

WHICH SYSTEM MATTERS?

In most cases: all of them! To conquer a sharp turn, short sprint, quick jump, you may need to tap into the ATP-CP system. For a step hill or quick series of jumps the glycolytic pathway is called, whereas for sustaining the activity for a long time, the aerobic system is also being required.