Question

lactic acid fermentation is anaerobic. this occurs when our body switched from aerobic respiration to anaerobic respiration. why do your legs hurt after running for a while? too many mitochondria a buildup of lactic acid a buildup of atp

Explanation:

When running, if oxygen supply is insufficient, the body undergoes lactic acid fermentation. Lactic acid accumulates in muscles, causing the burning and soreness sensation. Mitochondria are related to aerobic respiration (not the cause of the pain here), and ATP is the energy - carrying molecule (its buildup is not the reason for leg pain in this context).

Answer:

a buildup of lactic acid