Answer:
During exercise your cells need energy to function. in order to do so they harness it through ATP. In order to get ATP the cells convert it to ADP usually through aerobic respiration. Aerobic respiration requires oxygen to function and the cells will use up all their oxygen stores for it. Cells will get more oxygen when the exercise has been completed through the pulmonary system delivering oxygenated blood to the cells and taking away the used CO2 rich blood.
