Can carbohydrates be used for energy in the absence of oxygen?

Carbohydrates can indeed be used for energy without the presence of oxygen, which is facilitated through the anaerobic system. When exercise intensity is high and oxygen is limited, the body relies on anaerobic metabolism to produce energy quickly. This process primarily involves glycolysis, where glucose is broken down into pyruvate, and in the absence of sufficient oxygen, pyruvate is further converted into lactate. This allows the body to continue generating ATP (adenosine triphosphate), the energy currency of cells, enabling performance in high-intensity or short-duration activities.

While it's true that aerobic processes are efficient for long-term energy production, especially during moderate-intensity activities when oxygen is available, the anaerobic system provides a crucial alternative for immediate energy needs that allows for continued muscular performance in oxygen-deprived situations.