Energy - (Deadliest Style of Martial Arts)

Energy....this topic is very subjective. From martial arts view, everyone need an energy to defeat enemy. But what's energy really is???? Yeah..energy is our strength used to do somethin. Every single movement we do need an energy. Please noted that we using our energy 24 by 7... Even when we're sleep!!!!!But what's relation of energy bewteen the concept of deadliest stylel of Martial arts???