Cori cycle

G6P is readily fed into glycolysis, (or can go into the pentose phosphate pathway if G6P concentration is high) a process that provides ATP to the muscle cells as an energy source.

When the supply of oxygen is sufficient, this energy comes from feeding pyruvate, one product of glycolysis, into the citric acid cycle, which ultimately generates ATP through oxygen-dependent oxidative phosphorylation.

When oxygen supply is insufficient, typically during intense muscular activity, energy must be released through anaerobic metabolism.

From an intuitive perspective, gluconeogenesis reverses both glycolysis and fermentation by converting lactate first into pyruvate, and finally back to glucose.

The intensive consumption of ATP molecules in the Cori cycle shifts the metabolic burden from the muscles to the liver.

This repays the oxygen debt so both the electron transport chain and citric acid cycle can produce energy at optimum effectiveness.

[4][5] The contribution of Cori cycle lactate to overall glucose production increases with fasting duration before plateauing.

Cori cycle
Carl Cori and Gerty Cori jointly won the 1947 Nobel Prize in Physiology or Medicine , for their discovery of the course of the catalytic conversion of glycogen, of which the Cori cycle is a part.