Anaerobic
The term anaerobic refers to the type of energy metabolism carried out by your body without oxygen. Anaerobic metabolism, or anaerobic glycolysis is used to meet the body’s energy needs at higher levels of intensity. It uses carbohydrates (glycogen or glucose) to rapidly produce energy for the body.
The end product of anaerobic metabolism is lactate, which requires aerobic metabolism (and hence oxygen) to remove from the bloodstream. Any bout of exercise over a few minutes, therefore, cannot be sustained solely through anaerobic metabolism.
Keep in mind that the different types of energy systems used by the body to fuel exercise are not mutually exclusive. They all operate during exercise but to differing degrees depending upon the intensity of the exercise.