when does anaerobic respiration start

Question

When does it begin? "Anaerobic respiration takes place at the onset of exercise for up to 90 seconds. Repeated bouts of short and intense exercise, such as sprinting, increases the rate of anaerobic respiration. If exercise continues beyond 90 seconds, the cells rely on aerobic respiration to make energy, increasing the rate of aerobic respiration. Weight training and sprinting rely on anaerobic respiration, while running a half-mile or longer race or taking an aerobic dance class engages aerobic respiration." I do not understand this

Answer 1

Anaerobic respiration begins when the body recognizes it does not have enough oxygen to produce adequate amounts of ATP. ATP is a biomolecule created during cellular respiration, and is the main energy producing molecule in organic molecules. Oxygen is the final electron acceptor in cellular respiration and leads to the creation of water. If you do not have oxygen present the sugar can only undergo glycolysis and fermentation