<span>Because you are running so fast, your body produces a lot of lactate. Along with this lactate comes a hydrogen ion (H+), and you can’t have too many of these in the body because they will make the body fluids acidic. So the body “buffers” the H+ using biocarbonate (HCO3-) which produces CO2 and H2O. This raises the CO2 concentration of your blood, which is detected by receptors in the aorta and carotid arteries, and the respiratory centre of the brain, which then causes you to breath more deeply and more frequently.</span>
