One of the first questions people ask me when they do a freediving is…
‘How do I know that im getting close to my limit’?
I use, and teach a very simple breakdown of breath-hold.
I call it…The rule of thirds:
Fundamentally every breath-hold, no matter how advanced you are can be broken down in to three sections.
1st section: No real desire to breathe. Generally comfortable.
2nd section: Starting to feel the effects of C02 build-up. A general urge to breathe. Some hints of peripheral vasoconstriction.
3rd section: The final section, dominated by diaphragmatic contractions and low 02 levels.
So what does this mean for you? Well, think of it like this….
If you are coming up at the beginning of feeling the general urge to breathe then you are robbing yourself of potentially two thirds more time underwater.
If you hit your first contraction, freak out and come up, then you could have nearly a whole third more time still to go.
If you look at the graphic above you will see the ‘danger zone’ section near the end of the final zone. This is where you are reaching your actual low 02 thresh-hold. Learning to identify this ‘zone’ is a matter of progressive training.
Extending the rule!
As we progress in our training, we can extend each third, thereby extending our maximum breath-hold. We start to increase our c02 tolerance, so we feel the onset of the 2nd third later and can deal with it for longer when it does arrive. We can increase our body’s ability to work on lower than normal oxygen levels, thereby extending the final third as well.
The danger zone.
The most dangerous part of any dive is of course when the partial pressure of oxygen in the brain gets to a point where it can no longer sustain consciousnesses. As we progress with our training we slowly push of c02 threshold back (we also push our 02 threshold back, but often slower as it is more closely connected to fitness and condition), learning to deal with the 2nd and final third and moving us closer to the ‘Danger zone’. This may take months or years to achieve.
In-fact, new freedivers (as long as they follow training guidelines and have formal training) are often less likely to blackout/loose motor control than some more advanced divers, simply as they as new divers have a lower tolerance to c02 so will come up sooner, far away from the ‘danger zone’. A more advanced diver, with a higher c02 tolerance will often push through the 2nd third and the final third all the way to their low 02 threshold therefore risking loss of motor control or blackout. The c02 safety zone is critical and is what keep us diving within our limits, respect it.
Be safe!
Remember, this is a VERY rough guide to breath-hold and the sensations within it. It gives us as freedivers something to focus on when we are training, and is especially useful for new freedivers to judge where they are in their breath-hold.
Always dive with a buddy, never dive alone!
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