Lactic acid is not removed quickly because of what condition?

Lactic acid is not removed quickly because of what condition?

• A. High altitude
• B. Lack of oxygen
• C. Adequate oxygen
• D. Excess oxygen

Answer: (B)

When oxygen supply to the muscles is limited, the body relies on anaerobic glycolysis to keep producing some energy. Pyruvate is converted to lactate to regenerate NAD+, allowing glycolysis to continue even without oxygen. However, removing lactate requires oxygen-dependent processes: lactate can be oxidized back to pyruvate in the mitochondria for entry into the Krebs cycle, or transported to the liver to be converted into glucose. Without enough oxygen, these pathways can’t operate efficiently, so lactate isn’t cleared quickly and accumulates. A situation like high altitude reduces available oxygen, but the key factor slowing removal is the lack of oxygen in the tissues. Adequate or excess oxygen would enable faster clearance, not slow it.

When oxygen supply to the muscles is limited, the body relies on anaerobic glycolysis to keep producing some energy. Pyruvate is converted to lactate to regenerate NAD+, allowing glycolysis to continue even without oxygen. However, removing lactate requires oxygen-dependent processes: lactate can be oxidized back to pyruvate in the mitochondria for entry into the Krebs cycle, or transported to the liver to be converted into glucose. Without enough oxygen, these pathways can’t operate efficiently, so lactate isn’t cleared quickly and accumulates. A situation like high altitude reduces available oxygen, but the key factor slowing removal is the lack of oxygen in the tissues. Adequate or excess oxygen would enable faster clearance, not slow it.