Which process can occur in muscle cells when oxygen is scarce?

When oxygen levels are low in muscle cells, lactic acid fermentation is the process that takes over to produce energy. This anaerobic process allows for the continued production of ATP without the need for oxygen. During intense exercise, the demand for energy can exceed the oxygen supply available for aerobic respiration. As a result, muscle cells convert glucose into lactic acid, generating a small amount of ATP in the absence of sufficient oxygen.

Lactic acid fermentation allows for a quick release of energy, but it is not sustainable for long periods, as the accumulation of lactic acid can lead to muscle fatigue and discomfort. This mechanism is crucial for short bursts of high-intensity activity, such as sprinting or heavy lifting, where oxygen cannot be delivered quickly enough to meet energy demands.