A few questions... (Breathing Up Technique and diving environment)

[TogaLive]

So, I just had a couple quick questions.

Regarding breathing preparations for a dive, I have encountered very mixed views on just what to do to "Breathe Up" for a dive. Personally, I have been practicing static apnea on land, and I do so by doing the following:

-Breathe deeply, but calmly and at a normal rate for 5 minutes (usually start to feel a tingle in the fingertips after 5 minutes from the oxygen, typically a sign im ready)
-Take 3 - 5 deep deep breathes (exhaling each time), still at a normal rate, no hyperventilating
-Exhale on the last breathe forcefully, dumping as much air from my lungs as I can.
-Breathe in, filling up lungs to 98% capacity and begin apnea.
-Take 3 minute break after apnea while breathing normall, and begin the cycle again.

Doing this I've gone from a time of 2 min 30 sec to an even 4 minutes of breathe hold on land after a total of 6 attempts. I'm expecting to be able to reach 5 minutes (maybe 6 if im lucky) within a month, considering ive seen this improvement over 3 days (6 total times holding breath) and factoring in diminishing returns.

So here are my questions:

1) What is a good amount of time to provide plenty of bottom time during a dive, say, on average to 60 ft. This is a goal I will shoot for on land while I continue to practice dynamic in the pool (theres nowhere to dive around here). Is 4 minutes already sufficient? Im having a hard time factoring things out considering dive reflex and the slowing of my heart rate mixed with the exertion of finning.

2) Is my technique for breathing up correct? The last thing I want to do is practice poor technique and get great results, then go out and dive and get hurt.

Just to clarify, I have no plans of going out and diving down to 60ft on my first try. During the summer when I get to start up, I plan to dive shallow and slow. Then progressively work my way to deeper water as my lung capacity increases. My goal will be to always move slowly as I do during my dynamic (normally i will go 75 meters in the pool during dynamic at a slow leisurely pace).

So no worries, I am not a case of yet another diver who straps on some Freediving fins and thinks he can go to 90ft on his first attempt lol I have every intention of doing this right

Thanks for the info!

P.S: Where I will be diving during the summer only has about 15ft visibility at best, usually around 10 ft. Considering I would of course be practicing 1 up 1 down, what would you recommend I do to increase the safety of diving? If I am down at 60ft at the end of the summer theres is no way my partner would be able to see me. I am considering diving while I have a partner who is scuba diving (possibly two for their own buddy sake) but this would have its own complications, because if they are down at 60, and I experience SWB at 10 or 15, they wont see me for quite awhile. Any suggestions?

 

[trux]

Your breath up is called hyperventilation. Although it brings a rapid and easy progress to every beginner, it is extremely dangerous, and counterproductive. Look up the term hyperventilation here in the archive to learn the details. It is a very frequent topic.

 

[Johan Andersson]

-Breathe deeply, but calmly and at a normal rate for 5 minutes (usually start to feel a tingle in the fingertips after 5 minutes from the oxygen, typically a sign im ready)

Hyperventilation means that you are eliminating more carbon dioxide from your body stores than you are producing by the metabolism, thereby reducing the blood CO2. The tingeling sensation you experience comes from low CO2 levels, not from high oxygen. The tingeling is a sure sign that you have been hyperventilating.

Hyperventilation can be done in a number of different ways (breathing fast or slow, deep or shallow). What matters is the total volume of air you ventilate your lungs with (the pulmonary ventilation). Each time you increase the total volume of air above what is needed for a balanced elimination of CO2, you are hyperventilating.

The formula:
Breathing frequency (breaths/min) x Tidal volume (L/breath) = Pulmonary ventilation (L/min)

Normal breathing:
12 breaths/min x 0,5 L/breath = 6 L/min

Example 1 (hyperventilation):
20 breaths/min x 0,5 L/breath = 10 L/min

Example 2 (still hyperventilation):
12 breaths/min x 2 L/breath = 24 L/min

/Johan

 

[TogaLive]

Hmmm, interesting, I would have thought I was on the right track since I was following guidelines put out by Dive Training Magazine, but I appreciate the realization!

So, if I have been doing it correctly, then what is the correct way to do it? And I'll admit, what I do not understand is why you see professionals sucking in as much as they can before a dive, is that not in itself a form of hyperventilation?

 

[trux]

Have a look at this thread: http://forums.deeperblue.com/beginner-freediving/64959-how-start-freediving.html

"Sucking in as much as they can", or more commonly "packing" will not remove CO2 from the body, hence the effects are different.

 

[cdavis]

Hi Togalive, welcome to DB. Its a very nice place.

What you are doing works reasonably well FOR STARTERS in static apnea. However, don't go near water doing that unless you have a well trained buddy, ready for a BO. I'm not familiar with "Dive Training Magazine", but if your breathup is what they are teaching for depth freediving, don't listen to anything else from them. That breathup can get you killed. The tingling in your fingers is caused by hyperventilation dropping your c02 level so low that your carotid arteries constrict, limiting blood flow to the brain. That's way deep into the negative side of hyperventilation. For spearos in my side of the world, that is a sure sign to stop breathing for a while, build your co2 and start over before diving. Breathup should be mostly about relaxation, breath normally. Many divers use purge breathes, a few (like 3) deep and fast breaths to blow off some c02 before diving. Limited purging,in itself, its not so bad(IMHO, Trux will probably differ) but purge breathing is tricky, because if you are already slightly hyperventilated (like many divers) purging flushes out way too much c02.

Surface time 3 times down time is a reasonable rule of thumb.

Buddy diving in bad vis is hard, but that should not slow you down. Try towing a buggy board or small float with a drop line. For 60 ft dives that can work quite well.

Dive time in 60 ft: A minute is plenty, you will work up from there with practice. Don't expect your pool times to represent open water diving, which should be substantially shorter.

Good luck and keep asking questions.

Connor

 

[Johan Andersson]

Connor, I agree with what you say except for one thing (details, I know, but just wanted to clarify).

The tingling in your fingers is caused by hyperventilation dropping your c02 level so low that your carotid arteries constrict, limiting blood flow to the brain.

Yes, hypocapnia (low CO2) decreases the blood flow to the brain, but this does not contribute to the tingeling in the fingers. The tingeling is peripheral in origin and not directly related to brain functions. It is the peripheral sensory nerves that are affected first of all.

To explain in greater detail, hyperventilation increases pH in the blood and this leads to a decreased ionized calcium concentration in the blood as well. A part of the calcium in blood plasma is ionized, the remainder being bound mainly to protein and to a lesser degree to carbonate and bicarbonate. Plasma pH regulates the ratio of ionized to bound fractions, and the respiratory alkalosis associated with hyperventilation causes a reduction in plasma ionized calcium concentration by increasing the bound fraction.

The tingeling in the fingers is caused by the change in ionized calcium concentration alone or in combination with the increase in pH, which increases the excitability of peripheral sensory nerve cells.

If hyperventilation continues beyond the point where tingeling starts, also the peripheral motor nerve cells (going to your muscles) can be activated, causing muscle contractions (almost as cramps). This is know as "hypocalcemic tetany" (involuntary contraction of muscles because of low calcium).

OK, so maybe the post became to long and detailed, but anyway, I just wanted to add what I know about this.

/Johan

 

[Johan Andersson]

One more thing. I'm convinced (and this is based on what I have seen in my previous studies, actually measuring the lungs' and blood's CO2 levels or rate of CO2 elimination) that more or less each time you consciously try to modify your breathing in any way before an apnea (breathe-up, purging, preparatory ventilation - whatever we may call it), you are hyperventilating.

It is just a matter about how much you decrease the blood CO2 with different types of conscious control of your breathing. In addition, just thinking about an upcoming apnea causes you to breathe more (unconsciously). The more and longer you increase your total pulmonary ventilation, the lower the blood CO2 will be. Finally, it is not enough just looking at either depth or frequency of breaths, it is the combination (the total pulmonary ventilation) that matters.

/Johan

 

[cdavis]

Johan, thanks, glad to be corrected. My grasp of physiological detail has always been a little weak. Very interesting and I agree totally that it is total pulmonary ventilation that counts.

Hate to steal the thread, but this is too good an opportunity.

It seems pretty clear to me that different people have different levels of co2 tolerance, probably a genetic thing. Regular, unconscious breathing regulates co2 level to whatever the individual is comfortable with. That should be different between individuals. Doesn't that result in divers starting to hyperventilate at different c02 levels, so the impact of mild hyperventilation should be significantly different for different divers?

Connor

 

[Johan Andersson]

Well, normal arterial partial pressure of CO2 (PaCO2) is 35-45 mmHg (4.7-5.9 kPa), so there is some individual differences. I don't know if or how that has any relevance for the effects of "mild hyperventilation" in different divers. Arguably, starting with lower PaCO2, a certain level of hyperventilation will lead to lower PaCO2.

In a study I did a few years ago, competitive apnea divers were instructed to prepare for a static apnea according to their own choice. They ended up with a PaCO2 of 16-24 mmHg (2.2-3.2 kPa). That is, all hyperventilated.

/Johan

 

[cdavis]

Ahhh, the dirty secret is exposed. Why am I not surprised?

Its not really a secret that most divers hyperventilate some, whether they know it or not. Seems to me a little bit is mostly safe and helpful, most of the time. Equally clear, huffing and puffing until your head spins and fingers tingle has obvious negative and very unsafe consequences. The trick seems to be where do you cross the line between helpful and dangerous. Back to my question and its corollary. If divers start "mild hyperventilation" at different levels, are some substantially more susceptible to getting into dangerous territory?

Connor

 

[trux]

Yes, freedivers hyperventilate even if they think they don't. I often have to argue with many of them, but rarely they really accept it. If they hyperventilated mildly and always in the same way, it would not be such a big trouble. The problem is that the breathing is to big extent influenced by aspects we do not control, so it is enough to have a new unknown factor, like stress (competition, new environment,...), fear (bad weather, dark,...), excitement (ha, a big fish over there!,..), or many others, and suddenly you ventilate more than usually, and you find yourself in the death zone without noticing it beforehand.

 

[TogaLive]

Just wanted to say thanks for all the great information! I really appreciated the link to that other thread, and I will make a point of NOT doing what I have been doing (Which can also be found below incase you were curious where I was getting it...

Apnea mania

 

[Johan Andersson]

Its not really a secret that most divers hyperventilate some, whether they know it or not.

No, it's in no way surprising. But many divers will not admit that they do it. I don't know if that comes from an idea that hyperventilation must involve rapid breathing, when in fact it does not. Even if you do not breathe faster than normal, you can still be hyperventilating.

Back to my question and its corollary. If divers start "mild hyperventilation" at different levels, are some substantially more susceptible to getting into dangerous territory?

I would guess some individuals would be more susceptible (assuming that this follows a normal distribution), but I don't know if they are "substantially more susceptible". Out of curiousity, is there any reason for you to assume that?

Trux, you highlight some important aspects as well. What is a reasonable degree of hyperventilation in a controlled setting may not always be the same in another situation.

/Johan

 

[Kars]

I just want to say that there are different ways of helping novices through the first steps of freediving. In the beginning in general the focus of the students is on quantity. More speed, more breathing, etc. Depending on the talent and teacher, this will shift towards quality. Efficient swimming, efficient breathing. A freediver goes in general from much hyperventilation to less and less, to even underventilation during his career.

Instructors advocating more hyperventilation, will have some quick, easy results in the most accessible way. It's a way to attract more people to try the sport.
The advantage is people quickly learn that freediving is fun and get into the sport, do a course.
The dangers easy to swim into a BO, are obvious to anyone who has done a freediving course. The disadvantages are a bit more nebulous to many. The CO2 alarm comes on hard, body burns extra O2 to restore the balance, hence less distance.

 

[aris ioannidis]

very interesting comments! So, when i take 3 deep full breaths per minute before my dive i definitely hyperventilate as i breath more than 20L/min... So far it does not seem to affect me but i better watch it..

 

[Johan Andersson]

A freediver goes in general from much hyperventilation to less and less, to even underventilation during his career.

Kars, I could agree that possibly hyperventilation is less pronounced the more advanced you get, but I doubt that freedivers ever underventilate (if you by that mean hypoventilation, the opposite of hyperventilation). This would mean starting the dive with higher CO2 levels than normal. At least, I have never witnessed that. Neither by CO2 measurements nor by estimations of the ventilation (L/min).

/Johan

 

[Kars]

Well Johan, how many liters /minute for a kg body mass do you recognise is needed in rest?

For depth I do breath very slow long breaths, though it's not underventilating yet I think, but I sure aim to retain the CO2 within, while relaxing and oxygenating my body. The last breath I exhale close to everything (That's in effect is lowering CO2), to fill it gradually up to full capacity.

Doing prana yama, I am underventilating, the increased CO2 induces contractions.

If I'm training on my bike, I deliberately reduce my ventilation, while still pushing the pedals.

Doing 16x50, pb 12'41" - I for sure need less CO2, wile O2 is ok. Having much CO2 in one's system is something I'm familiar with.

The goal of underventilating is for me to induce a quicker dive response, and reduce O2 consumption.

Practised freedivers need to breath carefully because it's so EASY to hyperventilate.

 

[Johan Andersson]

Well Johan, how many liters /minute for a kg body mass do you recognise is needed in rest?

The pulmonary ventilation averages about 6 L/min, so assuming a weight of 70 kg ("standard" value in these circumstances), you get approximately 0.086 L/(min*kg body mass).

/Johan

 

[Johan Andersson]

There is actually more to it than what I have posted before. What matters the most for pulmonary CO2 elimination (and O2 uptake) is what is called the "alveolar ventilation".

The aim with pulmonary ventilation is to renew the air in the "respiratory zone" of the lungs (the alveoli, alveolar sacs, alveolar ducts, and respiratory bronchioles). The rate at which new air reaches the respiratory zone is called alveolar ventilation. Some of the air a person breathes never reaches the respiratory zone but simply fills the "conducting zone" where gas exchange does not occur (such as the nose, pharynx, and trachea). This air is called dead space air because it is not useful for gas exchange. It averages about 0.15 L. On expiration, the air in the dead space is expired first, before any of the air from the alveoli reaches the atmosphere. Therefore, the dead space is very disadvantageous for removing the expiratory gases from the lungs. The gas in the dead space will also be the first gas to enter the respiratory zone upon the next inspiration.

In a previous post I gave the following formula, but as you will see further down, it is not the whole truth.
Pulmonary ventilation (L/min) = Breathing frequency (breaths/min) x Tidal volume (L/breath)

Instead, it's the alveolar ventialtion that one must consider.
Alveolar ventilation (L/min) = Breathing frequency (breaths/min) x (Tidal volume - Dead space volume) (L/breath)

Alveolar ventilation with normal breathing pattern:
12 breaths/min x (0.5-0.15 L/breath) = 4.2 L/min

Hyperventilation 1 (double breathing frequency, same tidal volume):
24 x (0.5-0.15) = 8.4 L/min

Hyperventilation 2 (double tidal volume, normal frequency):
12 x (1-0.15) = 10.2 L/min

Hyperventilation 3 (5 sec in, 10 sec out breathing pattern):
4 x (5-0.15) = 19.4 L/min

As you see, changing the tidal volume is very important for the alveolar ventilation as the dead space volume is a fixed value. A doubling of the volume changes the alveolar ventilation more than a doubling of the frequency.

What I mean is, it is not only the volume that matter, to be honest also your breathing pattern affects how much CO2 will be eliminated.

/Johan