What is the predominant energy system used during high intensity, short duration activity lasting up to 3 seconds?

The main energy system during high intensity, short duration work lasting up to 3 seconds is the ATP-PC system. This is an anaerobic energy system which uses phosphocreatine as its fuel source. PC (phosphocreatine) is broken down by creatine kinase to form a phosphate molecule, creatine and energy. This energy is used to resynthesise ATP from ADP and P, to allow for muscle contraction to occur.