energy is released when atp is broken down into adp.
ATP hydrolysis. ATP hydrolysis is the reaction by which chemical energy that has been stored in the high-energy phosphoanhydride bonds in adenosine triphosphate (ATP) is released, for example in muscles, by producing work in the form of mechanical energy. The product is adenosine diphosphate (ADP) and an inorganic phosphate, orthophosphate (Pi).