The Cori cycle refers to the recycling of lactate or lactic acid produced by muscle during anaerobic metabolism, the lactate is converted to glucose by the liver. When the ATP needs of a cell outpace its oxygen supply is limited, muscle cells produce ATP through lactic acid fermentation. This permits the regeneration of NAD+ so glycolysis can continue. The lactate diffuses into the blood and is taken up by the liver, which converts it back to pyruvate and then glucose (via gluconeogenesis). This glucose circulates in the blood, where it can be used by muscles if needed or stored as glycogen. This cycle allows the body to continue focusing exclusively on producing ATP while another organ, the liver, handles the lactate produced.