Lactic acid fermentation in humans primarily occurs when there is a lack of oxygen during intense physical activity. Under normal circumstances, our bodies rely on aerobic respiration to produce energy. However, during rigorous exercise, the demand for oxygen exceeds the supply, leading the body to revert to anaerobic processes to continue generating energy.
During this anaerobic respiration, glucose is broken down into pyruvate through glycolysis. In the absence of sufficient oxygen, the pyruvate is then converted into lactic acid. This conversion allows for the regeneration of NAD+, a necessary coenzyme that enables glycolysis to keep running, providing a temporary boost of energy.
While lactic acid can accumulate in the muscles, causing temporary fatigue and soreness, it’s a critical process that allows us to maintain activity levels even when oxygen is scarce. Once normal oxygen levels are restored, lactic acid is converted back to pyruvate and can be utilized for energy through aerobic respiration again.