Which type of metabolism leads to lactic acid buildup during strenuous exercise?

During strenuous exercise, the body often requires energy at a rate that exceeds the oxygen supply available for aerobic metabolism. In this situation, the body shifts to anaerobic metabolism, which can generate energy without the use of oxygen. Anaerobic metabolism primarily involves glycolysis, a process that breaks down glucose to produce ATP (adenosine triphosphate) quickly.

However, one of the by-products of glycolysis when it occurs under anaerobic conditions is lactic acid. As the process continues, especially during sustained high-intensity exercise, the accumulation of lactic acid in the muscles can lead to fatigue and discomfort. This is why anaerobic metabolism is associated with lactic acid buildup; it allows for rapid energy production in the absence of sufficient oxygen, albeit with the trade-off of producing lactic acid rather than carbon dioxide and water, which are produced during aerobic metabolism.