What is the major by-product produced during anaerobic glycolysis?

During anaerobic glycolysis, glucose is broken down to produce energy in the absence of oxygen. The main by-product of this metabolic pathway is lactic acid. When the demand for energy exceeds the oxygen supply, the body relies on anaerobic glycolysis, which rapidly converts glucose into ATP, the energy currency of cells.

As this process occurs, pyruvate is produced but, without oxygen, it cannot enter the aerobic respiration pathway. Instead, it is converted into lactic acid, which can accumulate in the muscles and may lead to feelings of fatigue. Understanding this mechanism is crucial for anyone involved in fitness or personal training, as it highlights how the body adapts to different energy demands based on the availability of oxygen.

In the context of the incorrect options: carbon dioxide is a by-product of aerobic respiration, oxygen is a reactant required for aerobic pathways, and glucose is the substrate being broken down. Hence, lactic acid is the key product that surfaces specifically when anaerobic glycolysis takes place.