One big contraction

[Robwynge]

Hello All,

I have been lurking on these forums for a few years but I recently (finally) started Co2 tables and its lead to to question. I'm still new to this (despite my lurking) and so my max static is a whopping 60 seconds, which I guess means I have very low Co2 tolerance.

But my question stems from the fact that I have noticed that I don't really get contractions. Instead, I think I get one really big one. That is, I am doing a hold and things start comfortably, then the pressure builds moderately, then finally the pressure goes what I call "exponential," where my diaphragm seems to do one big contraction that keeps getting more intense with each passing second and it causes a huge and increasing pressure in my chest. Within 10-15 seconds, it feels like my chest and head may burst if I keep going, so I stop.

I guess I am having trouble guaging what my true max is and what my body is telling me about how much further I should be going, since I don't seem to get these multiple contractions that I keep reading about.

So does this mean anything other than I am a raw beginner and it will get better with training? Or do you all get this too and then get multiple sudden contractions beyond this point, so it just means I need to keep going? Or is this "exponential" increase in pressure the universal sign it's time to stop?

Thank you all for your assistance!

 

[hteas]

You might try doing a series of breathholds, each longer than the last (like the tables). Stop the first one as the first signs of difficulty. Breathe for a couple of minutes, then try again, and see if you can get further. It can take over 20 minutes for the dive reflex to kick in, so give it some time, and several efforts.

 

[Mullins]

It can take over 20 minutes for the dive reflex to kick in

Reference?

 

[azapa]

Reference?

I thought that too until I tried no warm up dives. Most spearos I know will tell you the same: they need to "open" their lungs with a few dives before they feel OK.

I think it's a very common opinion in most spearo's who have not experimented no warm up in the pool or in depth competitions etc. The adaptation curve is quite uncomfortable enough (in most) to put them off trying.

 

[cdavis]

In my experiance, no reference here, just start diving and 20 minutes or a bit more is a reasonable round figure for how long it takes to warm up(and get my dive reflex up to speed). Doing exhales or no warm up dives speeds things up a whole lot, but like azapa says, its "quite uncomfortable" if I'm in a hurry.


Connor

 

[Mullins]

Warmup, sure. DR seems quite different.

 

[hteas]

Dave,
Care to expand on that?

 

[Mullins]

As far as I know, warming up involves a reduction in the strength of the dive response. I.e. it's very strong on the first dive and you feel terrible, then as it subsides you begin to feel better. I think it's probably a good idea for people to start thinking of the two separately. It would be useful for beginners to understand, for example, that they're always making a tradeoff between comfort and safety; as opposed to the win/win equation that's commonly taught.

Robwynge - doing warmup dives will help, relaxing for several minutes before each one will also help if you're not already doing it. As you get more experience and get better at relaxing all the bits that are under voluntary control, you'll probably find that the general feeling of pressure separates out, in terms of both location (diaphragm / intercostal muscles) and time (distinct contractions with a less unpleasant break in between). For most people anyway. Not everybody.

 

[cdavis]

Well put, better than my post. Safety and and one off max performance are traded off against comfort and serial diving.

However, DR is a bit complicated. You do get the strongest immediate blood shift with the no warm up approach and that aspect of blood shift gets less with subsequent dives. But blood shift into the lungs ( a little different from cutting off the extremites) is cumulative over several dives and is a substantial contributor to depth ability, especially if you are diving at less than full lung. I'm speculating at this point, but oxygenated blood accumulation in the lungs should contribute to safety and dive time, no idea how much. So, for serial diving, some aspects of DR get better with warmup.

 

[ThomasB]

Hello All,

I have been lurking on these forums for a few years but I recently (finally) started Co2 tables and its lead to to question. I'm still new to this (despite my lurking) and so my max static is a whopping 60 seconds, which I guess means I have very low Co2 tolerance.

But my question stems from the fact that I have noticed that I don't really get contractions. Instead, I think I get one really big one. That is, I am doing a hold and things start comfortably, then the pressure builds moderately, then finally the pressure goes what I call "exponential," where my diaphragm seems to do one big contraction that keeps getting more intense with each passing second and it causes a huge and increasing pressure in my chest. Within 10-15 seconds, it feels like my chest and head may burst if I keep going, so I stop.

I guess I am having trouble guaging what my true max is and what my body is telling me about how much further I should be going, since I don't seem to get these multiple contractions that I keep reading about.

So does this mean anything other than I am a raw beginner and it will get better with training? Or do you all get this too and then get multiple sudden contractions beyond this point, so it just means I need to keep going? Or is this "exponential" increase in pressure the universal sign it's time to stop?

Thank you all for your assistance!

Had the same feeling when started some years ago. You are on the edge of the first contraction but pull out before. Just hold on a bit longer, let that pressure find its way into your first contraction...

 

[ThomasB]

Had the same feeling when started some years ago. You are on the edge of the first contraction but pull out before. Just hold on a bit longer, let that pressure find its way into your first contraction...

I mean, I would be surprised to get contraction on the first 60 second of a static

 

[baiyoke]

But blood shift into the lungs ( a little different from cutting off the extremites) is cumulative over several dives and is a substantial contributor to depth ability, especially if you are diving at less than full lung. I'm speculating at this point, but oxygenated blood accumulation in the lungs should contribute to safety and dive time, , no idea how much. So, for serial diving, some aspects of DR get better with warmup..

Damn.. Never thought of that... Don't want to get the thread off track, but just a quick comment:

You most also consider: The blood is taking up space in the lungs - the question is, if it contains more oxygen that the same amount of airspace would have... probably not...

And consider also: If bloodshift occurs at the first (no warm-up) dive, you will get the benefit from BOTH the air, and the bloodshift-blood in lungs AND the air+bloodshift will aid more on keeping the lungs above crush volume...

All in all I'd say that even in deep diving no warm-up is theoretically the strongest and safest approach... (unless of course you need actual flexibility warm-up).

 

[Mullins]

blood shift into the lungs (a little different from cutting off the extremites) is cumulative over several dives and is a substantial contributor to depth ability

I missed this post. Are you talking about resistance to injury? Not sure I'd call this part of the DR, because it's a mechanical effect of pressure and not an active response by the body.

 

[Kars]

Hi Robwynge,

To make your breath holds more comfortable and longer, become more flexible, and learn to relax all the body parts. Also practice a lot of repetitions, like an CO2 table. Don't do a full breath, 85% full is much more comfortable to hold. While holding at the start of the pressure build up, you can on purpose contract and release your diaphragm, as an exercise.

Walking over grass / sand apnea is also an idea, because you can focus on your walking, and the movement helps to relax.

Let us know how you go.


Love, courage and water,

Kars

 

[cdavis]

" if it(blood shifted into the lungs) contains more oxygen that the same amount of airspace would have"

Interesting point, and I don't know the answer. Since I'm diving about 1/2 lung and cumulative bloodshift appears to be considerable for me, I'd assumed there was more 02 in the blood than in the lost air space. I could be wrong about my case, and diving full lung might give a different answer.

"Are you talking about resistance to injury?" Yes. For those of us diving exhale, cumulative blood shift appears to be a major factor in increasing depth ability over the diving day. I can equalize down to the limit of my chest flexibility (sometimes). The elephant sits on my chest about the same time as the last EQ. Getting there is a lot easier(and shallower) when diving 1/2 lung. For me, squeeze injury is very easy.

Is that part of DR? The injury is not, but resistance to it seems to me to be included. Point I should have been making earlier is that DR includes more than simple bloodshift. The body appears to adapt in a lot of ways and we don't understand much of it.

Connor

 

[Mullins]

Is that part of DR? The injury is not, but resistance to it seems to me to be included. Point I should have been making earlier is that DR includes more than simple bloodshift.

What makes you think it's part of the DR?

Don't think anybody is saying bloodshift is the only component of the DR, but since both bradycardia and vasoconstriction diminish with successive dives it seems reasonable to assume improvement in squeeze-resistance is down to exposure to pressure, not an active response by the body that gradually gets stronger. Similarly, a series of surface statics (i.e. DR but no pressure) wouldn't be fantastic preparation for an FRC dive.

 

[Kars]

Some simple reasons why later deep dives feel easier:

- Muscles get stretched and warmed up,
- People get used to feeling of compression, therefore are able to relax better.

In 2005 I started doing no in water warm ups for Nordic Deep in Sweden, because doing them in a 3mm suit would cool me down and consume my buffers before the competition dive. Instead I warmed up and stretched the muscles used on land. Now many people are doing that in Sweden. After Tom Sietas doing no apnea preparation for statics, and others no apnea preparation for dynamics, I think no apnea depth preparation is a development to be expected.

Dave what part of the top deepdiving people have already done away with any breath-hold before competition deepdiving?

 

[cdavis]

Dave, are we talking past each other? I get the feeling we are not disagreeing.

Pardon me if I answer the wrong part of the question.

There are other aspects, but I'll just deal with residual blood shift here and its effect on depth ability in serial diving. You may be able to get as much blood shift to the lungs with a one off, no warmup max dive and the very strong DR that goes with it, but it is neither comfortable nor even possible with serial diving.

Especially for divers using less than full lungs, say 50 percent inflation, cumulative blood shift appears to be substantial. A minimal ventilation approach to breathup helps maintain it. Diving full lung reduces it, taking lots of long full breaths after surfacing also reduces, might eliminate, the cumulative effect by forcing blood out of the lungs, but I don't have much feel for how much. In any case, cumulative blood shift fills space that would be occupied by air, effectively reducing RV and increasing the depth to which you can dive. Surely that is part of blood shift, part of the bodies DR.

Bradycardia, vasoconstriction and blood shift are different sides of the same thing. The intensity of the first two do diminish in successive dives, but blood shift's cumulative nature means that, while the blood shift on any one dive may diminish with successive dives, a diver can start each successive dive with greater and greater levels of blood remaining in the lungs. This has considerable ramifications for serial diving.

Connor

 

[baiyoke]

Dave what part of the top deepdiving people have already done away with any breath-hold before competition deepdiving?

Now this thread is getting REALLY interesting!

I met a guy training who did 1 single dive every 48 hours. ONE! dive. No warm-up dry or wet. Just that one single dive. He did PB everytime for at least 2,3 or 4 dives, came up clean, and went to very impressive depths, 90+. Worked very well for him!!!

The intensity of the first two do diminish in successive dives, but blood shift's cumulative nature means that, while the blood shift on any one dive may diminish with successive dives, a diver can start each successive dive with greater and greater levels of blood remaining in the lungs. This has considerable ramifications for serial diving.

About serial diving: Doesn't people mostly stay above RV in serial diving? So they don't actually "need" bloodshift-in-lungs as I see it... Therefore having blood in lungs allready at surface would mean less air taken down as I see it... And again; having only air + the later bloodshift means bigger lungvolume at a certain depth ( or is perhaps just cancelled out, and is the same above RV-depth).

About wether bloodshift-in-lungs is part of DR or not: Interesting, I wonder if there's an oficial definition of DR or only a loose definition based on present knowledge. My own thoughts would be that it is part if a DR, but just not part of the same neurological response, but perhaps a mechanical one. I think the future will show that DR is many more things than presently known...

A minimal ventilation approach to breathup helps maintain it. Diving full lung reduces it, taking lots of long full breaths after surfacing also reduces, might eliminate, the cumulative effect by forcing blood out of the lungs, but I don't have much feel for how much.

Is the above a known fact, or personal experience?

 

[cdavis]

Little bit of both. I stumbled onto cumulative blood shift in my own training, was surprised and unsure that what seemed to be could really be the explanation. Looked all over the web, little information. Went back and read Seb Murats early stuff on DB and sure enough, its there, fairly well explained if you are looking for it, including what is happening and how to maximize it. Full lung and lots of deep breaths reduce cumulative shift because of simple pressure. Fill your lungs with air and that tends to press blood out of the lungs, just physics. My guess is that cumulative shift is a factor for all divers, but is something that doesn't jump out at you unless you do a lot of diving around half lung or less.

Connor