Harry, the swimmer with the fastest time on the Springfield College swim team, routinely hyperventilates before a meet, as he says, "to sock some more oxygen into my lungs so I can swim longer without having to breathe." First of all, what basic fact about oxygen loading has Harry forgotten (a lapse leading to false thinking)? Second, how is Harry jeopardizing not only his time but his life?
Harry has forgotten that It's the CO2 level, and not the O2 level, that causes a person to have the urge to breathe. In other words, once the CO2 level in the blood is high enough, the brain will trigger a breathing response, causing the person to try to gasp for air. Harry is jeopardizing his time and life because Hyperventilation itself reduces the carbon dioxide concentration of the blood to below its normal level, raising the bloods ph value, initiating constriction of the blood vessels which supply the brain, and preventing the transport of certain electrolytes necessary for the function of the nervous system.