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Old 12-02-2016, 06:46 AM   #58
Dr.P
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Join Date: Jan 2016
Posts: 199
Re: How long can you hold your breath?

Quote:
Originally Posted by Mullins View Post
A deep freediver is very much like a 100m sprinter. Muscles are working anaerobically. Lactate production, severe acidosis, to the point of failure.

What does vo2 max have to do with anything? We never operate anywhere near it. I was asking a pretty specific question.
This is not true. At the cellular level, the muscles of a 100m sprinter do not have time to process oxygen, even though it may be available. A 50m swimmer does not breathe, because that oxygen would do his muscles no good. On a 2 or 3 minute dive, your muscles have time to consume all the oxygen they want. The trick is limiting that oxygen consumption. The only way to possibly engage in anaerobic muscle activity that I can think of (at the cellular level!) would be to get some super stiff fins and sprint to the bottom of your dives as hard as you could go. I doubt that any instructors would advise this, however. Even when you feel "anaerobic" or more accurately feel like you're running out of oxygen, there is still plenty of oxygen available in your blood to fuel aerobic metabolism at the cellular level in your muscles. A simple pulse oximeter can visually prove this. The limiting factor is not the partial pressure of oxygen that is required to fuel your muscles, but the partial pressure of oxygen required to fuel your brain. Certainly you will produce lactate, even marathon runners do, or they could run forever. ...these are just the facts, I don't really have time to explain the differences in oxygen metabolism, but the knowledge is readily available.

Interestingly from a medical perspective, I can recall a couple of cases of high level endurance athletes involved in accidents that became hypoxic far beyond the accepted limit of survival without brain damage. In these cases, the athletes made a full recovery. Their survival was attributed to their extreme aerobic fitness and their body's ability to conserve oxygen and blood flow to the brain and heart far beyond the "normal".

I did not post to try and prove a right or wrong. What works for each individual person is great. My only real point was that no matter how fit anyone thinks they are, things can, and do, still go wrong. Dive safe.

Last edited by Dr.P; 12-02-2016 at 07:06 AM.
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