Why we breath faster after heavy exercise or running?
When a person is doing very heavy exercise and the blood cannot supply enough oxygen, another sort of respiration called canaerobic respiration occurs. This converts glucose into energy without the need for oxygen.
Anaerobic respiration releases less energy than aerobic respiration. But during anaerobic respiration, lactic acid builds up in the muscles. High lactic acid concentrations are painful and felt as cramp. When exercise stops, the blood supply is able to provide enough oxygen to convert the lactic acid to carbon dioxide and water but this takes time and the muscle pain may continue after exercise until the lactic acid has been converted. The delay in the removal of lactic acid is known as the oxygen debt. Carbon dioxide and lactic acid both cause increases in breathing rate and heart rate to allow the body to repay the oxygen debt. The oxygen debt is the reason why we continue to be out of breath even after exercise.