This is produced in the mitochondria which is the powerhouse of the cell. Because ATP cannot be supplied by the blood stream it must be re-synthesized in the cell. Creatine phosphate is the a substance that exists in limited quantities within the cells. This substance is hydrolyzed to form Creatine, energy, and phosphate. The energy that is liberated from this action is not mechanical energy.
Energy transferred in the form of phosphate bonds is termed phosphorylation.
Energy from phosphorylation is ultimately generated by the oxidation of carbohydrates, fats, and protein. This form of energy does not require the presence of oxygen so it is termed anaerobic. You use this form of energy when short maximal bursts are needed. For example the 50 yard dash, a lineman charging off of the line, or blinking your eyelids. This system will only provide energy for 20 to 30 seconds depending on the individuals tolerance to the lactic acid that is produced as a byproduct.