There are three Metabolic Pathways which are Immediate, Short Term, and Long Term Energy System Pathways. Immediate System also known as ATP-PC is used only for a brief durations of up to 10 seconds. What’s interesting about this system it doesn’t use oxygen nor produces lactic acid, but it is stored within muscles. Once the body uses all the immediate energy it switches to the short term system as its main energy supply. An example of it Immediate Energy is powerful movements like a golf swing, a 100 meter sprint or powerlifting. Here’s a fun fact the better the muscle mass that an athlete have, the more immediate energy they have. Many runners rely on this system to help hence their large muscle mass. Next is the Short Term Energy which