this could get an interesting thread. I for myself would say that a lot of pros do hyperventilation as well but as well in somewhat "controled" forms. I for myself think it is somekind of technique without competetive freediving might be barely where it is now. Hyperventilating prolonges the start of urge to breathe and that urge does a good part in using up oxygen in form of contractions or general uneasiness. I would not recommend hyperventilating on non competetive dives and also with a good buddy while on training.
Robert
Hyperventilation is a Russian roulette, as trux rightly points out. I know many "pros" who get burned because active hyperventilation is a part of their breathe up. One of the primary reasons why it is dangerous to have purges and active breathing in your preparation for a deep dive is that we tend to naturally breathe more frequently when anxious about going deep. Those divers who use hyperventilation rely on a very delicate balance of ventilations. Add the extra anxiety and it falls apart. I've seen this happen so many times at every level, and to a well known World Record holder.
I would never recommend hyperventilation in any case, whether competitively or not.
You really don't want to experience a hard dive after having hyperventilated. This is how it usually goes: the descent feels great! no tingling in the lungs, not feeling of being too deep. You turn around and still nothing. Then closer to the surface (and hopefully you are close enough) you suddenly get a huge mother contraction of the diaphragm. This is no ordinary CO2 contraction. I would call it a hypoxic contraction. Then you know you are screwed. Or you've already started to fade out. This is the story of overbreathing that I hear over and over again. If you want to see for yourself, do a max static in the pool with a good spotter and you'll likely experience the same feeling. In the pool, you'll notice the buzzing in your arms and legs and then suddenly when the contractions hit you, it really sucks.
It is a problem to know whether you are hyperventilating or not. My solution is a combination of intermittent breath holds and sub-neutral natural breathing. Sub neutral breathing = tidal volume = easy breathing = taking breaths without actively using the muscles of the rib cage and thorax to take a breath, as follows:
Surface from the dive:
--hook breath and hold (5 - 10 seconds)
--deep breaths, preferably through the nose to recover (10-20 seconds)
--face down with snorkel:
sub-neutral breathing 4-6 breaths /min
with 20 second holds every 3-4 breaths (I don't time the holds, they tend
to happen naturally, now)
--when I've rested enough (usually 1.5 - 2x previous dive time), and I feel "good" again, then I inhale fully, then exhale and dive.
That's my usual breathing pattern that has evolved over the years to avoid overbreathing.
Another important thing about avoiding purges or active ventilations is that if you do use them it becomes very difficult to calibrate your sensations of well-being underwater. You'll be throwing in a lot of misleading data into the mix. When I dive, I can be fairly certain that feeling the urge to breathe early in the dive is usually the result of me wasting energy in the descent or not being sufficiently rested. If that's the case, I abort the dive (I'm talking recreational diving).
One of the reasons I much prefer to dive FRC these days is that their is much less of a reason to hyperventilate. Inhale divers create a lot of CO2 on the descent while overcoming the buoyancy of their lungs, especially if they pack. This tends to cut the dives short. What's the apparent solution? Reduce the urge to breathe and extend the dive, especially the comfortable phase. :naughty There be dragons.... The FRC descent if done properly creates very little CO2.
Whether you pack, inhale, partially inhale or exhale for your dives, part of learning to freedive safely is the find a way to dive without having to cover up inefficiencies with hyperventilation and purges. Many divers are guilty of the that, because it's not easy.
Pete
