Which substrate primarily fuels anaerobic glycolysis?

The primary substrate that fuels anaerobic glycolysis is glucose and glycogen. During anaerobic glycolysis, carbohydrates are broken down to produce energy without the need for oxygen. Glucose, which is the simplest form of carbohydrate, is a direct source of energy for this process. Glycogen, the stored form of glucose in the liver and muscle tissues, is also readily available during high-intensity exercise when rapid energy is needed.

This energy production is crucial during strenuous activities where the demand for energy exceeds the oxygen supply, making the fast breakdown of glucose or glycogen essential. The process ultimately results in the production of ATP (adenosine triphosphate) along with lactic acid as a byproduct. Fats and proteins can contribute to energy production in other metabolic pathways but are not the primary substrates for anaerobic glycolysis. Fats primarily fuel aerobic metabolism, and proteins are typically used as energy sources during prolonged exercise or when carbohydrate stores are depleted. Ketones, derived from fat metabolism, are also not involved in the anaerobic glycolysis pathway. Thus, glucose and glycogen are clearly vital for fueling anaerobic glycolysis.