I am currently researching ATP breakdown and its use of the energy systems for re-synthesis. We are taught how the energy released from these systems allows Pi to reattach to ADP, but not how the ATP breaks down in the first place.
For example, the ATP-PC system is used for fast ATP regeneration, but when movement begins, what triggers the release of energy by ATP breakdown?
What he means I think is muscle movement. Look up myosin and actin protein and their involvement in muscle movement. ATP bonds to protein myosin which changes the conformation of the protein so that it can bond to actin protein adjacent to itself. When the movement is over the ATP releases, but the energy from the Pi has been used to change the conformation already and thus turns it into ADP and Pi.
