Glycolysis

Conversion of pyruvate to lactate occurs under anaerobic conditions, as full oxidation by the mitochondria is not possible in the absence of oxygen. By converting pyruvate to lactate, NAD+ is regenerated from NADH, allowing glycolysis to continue. Glycolysis itself produces ATP, although less so than mitochonrial oxidation, and supplies energy under anaerobic conditions. The lactate that is produced is recycled to the liver where it is reconverted to glucose. FADH2 and NADPH are not produced by glycolysis. Adrenaline stimulates muscle glycogenolysis, providing a local supply of glucose that is used by glycolysis.