Homolactic fermentation (producing only lactic acid) is the simplest type of fermentation. The pyruvate from glycolysis[10] undergoes a simple redox reaction, forming lactic acid.[3][11] It is unique because it is one of the only respiration processes to not produce a gas as a byproduct. Overall, one molecule of glucose (or any six-carbon sugar) is converted to two molecules of lactic acid: C6H12O6 → 2 CH3CHOHCOOH It occurs in the muscles of animals when they need energy faster than the blood can supply oxygen.