ATP resynthesis is the process by which the body and its muscles produce ATP. ATP is the main energy source of almost all living things, and while ATP is not energy itself, it temporarily stores energy in its bonds to be released on demand.
Humans resynthesize ATP through three metabolic pathways: the phosphagen system, glycolysis and the aerobic system. Each process is used to varying degrees, determined by how quickly and how much ATP the individual needs. The quickest way to resynthesize ATP is through the phosphagen system, which is used during short-term and intense activities. Glycolysis follows as the second fastest way to produce ATP. The aerobic system is the slowest, as it relies on a steady supply of oxygen.