Question

During heavy exercises our mucsle cells respire anaerobiacally justify pls answer fast and in paragraphs

Answer 1

this happens due to lactic acid

Answer 2

Answer:

Anaerobic respiration occurs most often in humans during vigorous exercise. When muscle cells use up their oxygen, they have to switch to an anaerobic pathway to process energy.

In aerobic respiration, subsequent to glycolysis (in cytoplasm) the pyruvate undergoes complete breakdown  in the mitochondria in the presence of oxygen, producing energy from glucose along with byproducts such as, water and carbon dioxide that are easily expelled by breathing.

Anaerobic respiration produces less energy; while producing lactic acid from pyruvate in the cytoplasm, which cannot be easily expelled.  Lactic acid builds up in muscles and causes soreness and fatigue.

So answer is- lactic acid.