I thought the ratio is important as essentially it makes sure roughly that the deeper your inhalations, the less of them you do. I understand there is no magic in the ratio but in practice it must limit the hyperventilation...
Yes, you are partially right, the depth of the inhalation is important. But in the exact opposite direction than you think: the deeper you inhale, the harder you hyperventilate. When breathing, there is a dead volume in the mouth and sinus, the trachea, and the bronchi, with little or no gas exchange in them. At normal flat breath, the inhaled or exhaled volume (~0.5 l) is hardly (if at all) bigger than the dead space, At deep exhales and inhales, the dead space gets flushed entirely very quickly, and most of the inhaled air volume is new air. It means you remove CO2 much more efficiently than with flat breathing. The simplified calculation in my previous post did not take it in account, the real level of hyperventilation would be in fact worse than shown at the deep pattern.
One question about your explanation - doesn't make full sense to me to say that if you take more L of air in it necessarily leads to hyperventilation...
That's the very definition of hyperventilation - it is a higher than needed ventilation (exchange of air in given time unit). Even if we ignore the influence of the dead space as noted above, 4x4 liters at deep slow pattern = 16 liters are 10L above the normal 12x0.5 = 6 liters (or almost three times higher ventilation). Hence hyperventilation. At 1x7 l we would be already close to the normal of 6l, hence lesser hyperventilation.
I don't think this is true at all. Amongst my circle of freediving acquaintances only the ones with informal training or those who have trained with instructors who are not up-to-date with freediving developments use hyperventilation. They are also the ones who samba and blackout all the time. HV is sooo 1994!
No, it is true. Already a single purge represents hyperventilation. Practically any kind of "deep relaxed breath-up" represents a rather serious hyperventilation. And the body starts hyperventilating alone when in stress or in preparation for performance, even without you doing it consciously. There is difference between moderate and excessive hyperventilation. At moderate hyperventilation, the advantages may overweight the reduced hypoxic tolerance, while not suppressing the contractions and the urge to breath beyond the safe zone. However, even at moderate hyperventilation the disadvantages are there, and especially it then happens easier that under stress or in a unusual situation you unconsciously over-hyperventilate, and find yourself beyond the safe zone.
