Anaerobic metabolism is a process by which cells generate energy without using oxygen. This occurs primarily during intense physical activity when the demand for energy exceeds the oxygen supply. The body breaks down glucose through a process called glycolysis, resulting in the production of lactic acid and a small amount of energy in the form of ATP. While anaerobic metabolism allows for quick bursts of energy, it is less efficient than aerobic metabolism, which uses oxygen. The accumulation of lactic acid can lead to muscle fatigue, making it important for athletes to balance both types of energy production during exercise.