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Old 08-11-2004, 03:30 PM   #6
Location: Houston
Join Date: Aug 2004
Posts: 3
Re: Dousing with cold water: Who does it?

I'm not a brain surgeon by any means, but I am a diving instructor. It is called the mamillian diving reflex and in short, when your face is submurged in cold water it triggers a response to the rest of your body to completely slow down, i.e. your heat rythm slows, your respirations decrease, the amount of oxygen your body comsumes decreases. It doesn't directly change your blood chemistry but it will alter it due to the fact that your body as a whole is slowing down. It's thought that this is to either allow for longer submurged lenthes underwater and/or to increase the survival time after plunging into cold water. This is where cases of children being submurged for extreamly long periods of time in near freezing water come from.
An amazing test for this is by filling two big bowls of water (having a saftey person there is a must) one with ice water and the other with room temp. Hold your breath in the room temp 2 or 3 times, take a 45 minute break (this again is a must, due to decreased carbon dioxide levels in your brain, which triggers your breathing reflex) and then hold your breath in the ice cold bowl. Make sure you are doing something while your head is in the water like wiggling your finger, tapping your foot, just in case the person blacks out so your saftey person can take your face out of the water. On average, for experienced divers, I found for room temperature breath hold is between 2-3 minutes, for the ice cold water it is 5 or 6 minutes or more and most people pull thier head out because they are cold and not cause they need to breathe.
Sorry I went off on a tangent there and please correct me if I am worng on any of those points if you know better, it has been a while since I went over my advanced physiology diving stuff.
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