Does Hyperventilating make you hold your breath longer?

Answer 1

Yes you can because hyperventilating causes you to blow off too much CO2, causing your arterial PCO2 to decrease (called hypocapnia). High levels of CO2 in the blood is the main control of the respiratory cycle, and is the drive for us to breathe.

Chemoreceptors respond to changes in CO2, and when the level is low such as after hyperventilation, these receptors trigger a reflex decrease in respiration by stimulating the respiratory center in your brain to slow down. Decreasing the number of times you breathe allows the amount of CO2 in your body to increase again from tissue metabolism (CO2 is an end product of tissue metabolism). As a result you can hold your breath longer at this time.

CORRECT ANSWER: No you can not! When your under water your brain tells you when you need to breathe so if you hypervetilate you loose a lot of the CO2 in your blood. So when you go under water after you have hyperventilated then your brain will think you don't have to breathe when you really do and it will cause you to black out without knowing so in the end it can be a life threatening thing.

Answer 2

No, hyperventilating does not allow you to hold your breath longer. In fact, the practice is very dangerous when used in connection with free-diving or swimming, and has been implicated in many fatal cases of "shallow-water blackout". According to folk wisdom, hyperventilating will increase the oxygen saturation of the blood, allowing for a longer supply of oxygen to the body. In fact, the blood should always be fully saturated when breathing normally in a standard atmosphere. (A very slightly higher saturation can be achieved by breathing pure or compressed oxygen.)

What hyperventilating does do is cause expulsion of excess carbonic acid from the blood, raising the pH of the blood. This in turn suppresses the urge to breathe. So while hyperventilating does not give you one more second of usable oxygen, it does make you more comfortable with not breathing. In extreme cases, it can make you so relaxed, that you black out from lack of oxygen without realizing it. If you're underwater at the time, this is bad.

Free-divers and competitive apneists are trained to recognize the signs of low blood oxygen (dizziness, loss of peripheral vision, etc). ALWAYS DIVE WITH A BUDDY!