Which Three Energy Systems Used To Create ATP?

There are 3 energy systems the body uses to create ATP. They are the ATP-PC system, the lactic acid system and the Aerobic energy system. Both the ATP-PC and lactic acid systems are anaerobic and therefore do not use oxygen, and the aerobic system does use oxygen.
When we begin to exercise the first system we would use to create ATP is the ATP-PC system. This system acts by creating ATP from phosphocreatine, making use specificially of the phosphate molecule. When energy is used or expended it becomes ADP (Adenosine Di Phosphate), and therefore needs one phosphate molecule to create energy. So the main fuel source for this system is Phosphocreatine. This system will last for up to 10 seconds and after that all the stores of phosphocreatine are depleted and cannot be replenished until the body rests. It can take up to 3 minutes for the stores of PC to be restored. An activity most suited to this system would be a 100m sprint or a golf swing.
This system works to perform anaerobic glycolysis to create ATP. The main fuel source for this system is glucose/glycogen. We store glucose in our muscles as glycogen and this is then used to create ATP. When glucose/glycogen is broken down by anaerobic glycolysis the end product is pyruvate/pyruvic acid. As there is no oxygen available the pyruvate joins with the surrounding hydrogen atoms to become lactic acid. Lactic acid causes the muscles to slow down and causes pain and therefore exercise cannot continue. This system will provide us with energy for up to two minutes and the sporting activity most suited to it would be a 400m