Pressure training

Residual volume

I dont mean to swerve off the topic too much but im wondering again ... how do we determine residual lung volume ? Is there a calculation ?

My definition of residual volume is the volume remaining once the lungs and surrounding ribs, organs and tissues have compressed as much as they are ever going to and after that something else has to give.. ie the fluid filling episode.

I can exhale 8l of air normally as measured by a spirometer and 10 L if i have packed. ( I can do 10 packs max, each of 200 ml )
I know that i cannot exhale all my air, so i wonder what the actual capacity is if one takes the remaining residual volume into account.
Will one have to reverse pack into the spirometer to get the full true volume and subtract the two to find the residual ?

Nevertheless, I know that Hubert Maier gets 14 litres with packing; Herbert has 7L without packing, 10L with packing. I have a spirometer, and in my case the most I ever got without packing was 7.89L, and with packing, 10.55L (with packing & reverse packing I once got 10.90L). I also once tried various positions

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When we quote lung capacity here and in casual discussion, is it our standard to quote normally exhalable air volume or is it this, plus calculated / measured residual volume ?

Does a knowledge of personal total and residual volume allow you to theoretically calculate the depth at which you will cease being able to equalise normally ?

Skindiver.

measuring lungs

This subject has been around here for a while. My old manual (1965) says residual volume is 24% (27% for females) of Vital Capacity. Vital Capacity is the volume you can exhale. I presume that packing isn't 'allowed'. If you want an exact number, the only thing that I've heard of, is adding inert gas to the inhale and measuring the dilution in the exhale.

If this 24% is true, then total lung volume is 124% of Vc and the squeeze will start at 40 meters for everyone (perfect conditions, no mask and no loss of air). If you fill your mouth with air here, 100 meters is do-able for ears and sinuses. The lungs however will have to squeeze to about 10% of total volume or use fluid. Packing changes this number.

Each diver does negatives a little differently. In order to use the same start point, I exhale most of the air, put my face in the water, exhale for 10 seconds more (including one full diaphram crunch), flood my mouth and then start down and 'reverse' a mouthful of air. I think this is the equivalent of 35-50 meters (depending on mask, packing and real world conditions). The only thing good about this, you can simulate depth in very shallow water and learning is way safer at 5 meters than 50.

Cautions. Things happen fast. The rib cage starts to complain by 3 meters the first time. Bottom time is greatly reduced. They're a lot more work than you think. It's easy to hurt yourself. A good buddy is 'worth her weight in gold'.

Aloha
Bill

Re: measuring lungs

Originally posted by Bill
This subject has been around here for a while. My old manual (1965) says residual volume is 24% (27% for females) of Vital Capacity. Vital Capacity is the volume you can exhale. I presume that packing isn't 'allowed'. If you want an exact number, the only thing that I've heard of, is adding inert gas to the inhale and measuring the dilution in the exhale.

Click to expand...

I'd guess that this number would vary quite a bit between individuals, depending on both their physiology and how well trained they are at breathing.

Some pretty extreme stuff going on here. Any input for a relative novice to negatives? Here's the thing; I exhale fully including a diaphragm squeeze but no reverse packing. I very carefully drop down to 15-20 feet (FEET boys not meters!) I get the squeeze feeling and something more, an uncontrollable coughing response which causes me to ascend quickly. It's as if rising squeezed tissues get pushed into some Cough/nerve/button. (words can't describe) My intuition is that with practice I'll extend my ranges and supress this coughing thing. Question; anyone else experiencing this coughing? Thanks TP

Lazy to check my sums..

Bill.

Nice answer thanks. If residual is about 25 % , I can see how lung squeeze will start between 30 - 40m odd, but with only a mouthful of air taken for equalising, it happens surprisingly shallower than i expected.

Normal lung compression schedule:

@ 10m lung volume is halved and pressure is 2 bar.
@ 20m lung volume is a third and pressure is 3 bar.
@ 30m lung volume is a quarter and pressure is 4 bar. ( at this point volume equals Bill's 25% odd, residual volume)
@ 40m lung volume is a fifth and pressure is 5 bar. The lung is being compressed to 20 % its origional volume, its now below 25 % residual volume.

The following should hold true for 6L total volume lungs including residual, no packing. (ie average for 35 y/o non smoker woman):

One mouthful of air, - whilst only about 200ml at the surface but about 600ml taken at 20m will leave you roughly at residual volume already.
2L remaining @ 20m as per above schedule.
take a mouthful - 600ml
2L - 600ml = 1.4 L (average 1.5L residual for 6L lungs). No real squeeze.

One mouthful taken @30m = 800ml, will eat into your residual volume by about 50%.
1.5L remaining at 30m as per above schedule.
Take a mouthful - 800ml
1.5L - 800ml = 700ml. Proper squeeze.

One mouthful taken @ 40m = 1L , will eat into your residual volume by about 83%.
1.2L remaining as per above schedule.
Take a mouthful - 1L
1.2L - 1L = 200ml. Mega squeeze. Your lungs are 35% smaller than a Coke can.

One mouthful taken @ 50m = 1.2L will eat into your residual volume by about 117%
1L remaining as per above schedule.
Take a mouthful - 1.2L
1L - 1.2 L = -200ml. Beyond squeeze and impossible. You now have 17% of your alveoli and mucous lining in your mouth.

Ps these mouthfulls are not cumulative. They are a single mouthful taken per dive.

Are my sums right ? I suppose this is how the doctors calculated that one cannot dive below 50m in Enzo's days.

Skin

volumes

TP
Same here. The coughing reflex also happens with too much packing or reverse packing. These old lungs are adapting though. If 20 feet is a simulated 200, it will take a lot more training before my legs can 'stretch' my lungs.

Skin
I enjoy going thru someone else's notes. I see a few things differently but I'm not sure that I'm right.
>@ 40m lung volume is a fifth and pressure is 5 bar. The lung is being compressed to 20 % its origional volume, its now below 25 % residual volume

my #'s...Vr=25% Vc=100% Total=125% at 40M=25% or Vr Vr is 20% of total or 25% of Vc

Some say that I'm a 'big mouth' but after three attempts, mine will hold less than 1/10 Liter. When packing, I get less than 1/20L per pack and even less when reverse packing. Size or real world figures,don't know why.

> One mouthful taken @ 40m = 1L , will eat into your residual volume by about 83%.1.2L remaining as per above schedule. Take a mouthful - 1L 1.2L - 1L = 200ml. Mega squeeze

That looks like an apple/orange comparison. If you have 1.2L in your lungs and you put 0.2 L in your mouth with no pressure change, then you have 1L left in the lungs. If the dead space in your throat, head and mask is 0.2L and you continue down to 90M and equalise, the dead space will be full, the mouth will be empty and the lungs will have 1/2L of air and, I presume, some fluid in them.

My stats look something like this;
1.25 Vr 5.25 Vc 0.1 mask 0.1(??) dead space 0.3 pack (10 times) or 7L total at the surface. Lung squeeze starts about 38M (less if I spill any air getting down). The empty feeling starts at 30M but, I was still able to pull air from my lungs below 40M yesterday.
Aloha
Bill
P.S. That dead space is part of Vr at the surface.

knew there had to be a mistake.

Nicely spotted Bill.

Seems i was trying to have it both ways on my ever expanding mouthfulls.

Your packs seems very small though and im sure its an individual thing. I have read though about people doing 60 packs and i've wondered how. It must be that they are doing baby packs. My packs are at 200ml each for sure. 8l Max inhale and 10L with 10 packs.
One thing i do is i drop my jaw and push my tongue base / throat outwards and get much more in that way per pack.
I've just tried packing now from empty empty and i cant even get 60 packs in from zero before im full.

skin.

Hey Skin
Curious. Our interests match and so do our methods. I just wish I could get 10 litres in these old lungs. Let's see, 10L instead of 6.5 means ?? minutes instead of 5:45.
Thanks for the hint on packing. Just tested, 10% increase over what I had per mouthful.

Aloha
Bill

Try taking your teeth out..

You could free up another 50cc

Kidding Bill.

Back to the squeeze calculations.
If i have 6 total L in my chest on the surface and at 40m i fill my mouth, a finite 200cc area, then the mouth must contain 1 pressurised L @ 40m, to match the ambient water pressure.
If i spat it out at 40m and then ascended to the surface i would have only 5 total L left on the surface.

I think the problem with my calculations is my confusion with literage as a measure of volume and contents. I should confine liters to the measure of contents and use cc ( cubic centimeters) as the measure of volume.
(after all a cylinder may have volume of 15000cc but have contents of less than 0L in a vaccum state, or 30L if pumped.)

If so then the Volume (cc) decreases with depth but the contents in terms of Liters dont decrease. 6L on the surface is still 6L @40m but at 40m its occupying a smaller space (cc) at higher pressure.

The equalisable areas do not shrink correspondingly but maintain their finite cc and this is why so much more air is required to bring them up to ambient water pressure.

So my calculations should have been subtracting the ever increasing Literage of the mouthful taken from a constant lung Literage, and @40m the result should have been 6L( lungs) -1L (mouth) = 5L ( left in lungs)

The 5L in the lungs is no longer a fully useful 5L though, as it has compressed to a small size (cc) that is begining to approximate or even overlap the surface residual cc and suffer the same difficulties one would experience in expelling the residual volume on the surface.

ie. 5L have been compressed into a Space of 1000CC @40m under 5 bar of pressure, which is less than the surface residual cc volume of about 1500 cc (25% of VC ) and this makes it difficult to get more out as well as precipitating the squeeze.

I rekon this might be right.

Skindiver

OK, lemme see if I'm following this...

For me as others have commented too much reverse packing results in an uningnorable scratchy feeling in the back of the throat. So for the following, I'll just work on the idea of doing negatives from a good exhale and keeping the complete RV.

Now, if RV is 25% of full non-packed capacity, then a dive to -10M would drop you to 12.5%. This would be equal to a -70M dive on a full breath without packing. Is this correct?

If you can do -20M on RV alone then that is the same as -110M on a full breath. WOW. Not that I can do anywhere close to that. I've only ever tried it in a pool (5M) and that was hard enough. Feet touched bottom but I was standing up, so probably only counted for -4M at best.

OK, now for the tricky one... Erik mentioned that you can simulate a -50M dive in a 5M pool with reverse packing. But, if my math is right... then you don't need to reverse pack. A full exhale to RV then a drop to -5M will be the same as -50M. Of course in the pool you're really not quite -5M unless you lay on the bottom like a flounder, but close enough, and easy enough if you've blown all your air. My reasoning, using the ongoing 6L lung example...

6L / 6ATA = 1.5L / 1.5ATA or...

100% / 6ATA = 25% / 1.5ATA

Now for those that regularly reverse pack, do you also get that itchy scracthy thing? Do you get used to it, or do you just know how much to reverse pack before going that far? Last question, probably much harder to answer, is there a typical percent of RV that can be removed by reverse packing? I don't have access to a spirometer so I can't test myself. Just wondering what can we really simulate in a 5M pool with reverse packing.

Appologies to Erik if my math is wrong...

Although I haven't been following this thread, I thought I would chime in on my experiences with this technique.

I usually practice this technique at the end of my pool sessions, usually 4-5 times. The idea being of course to work into it gradually so that by the last dive, I am on a forced exhale and laying on the bottom. This is typically only 4-4.5 meters in depth, but I then try to put myself in to a meditative state and see how long I can lay on the bottom in this skill - so far my longest has been 60 seconds on a forced exhalation... it actually felt pretty good. Keep in mind that you should always allow for a 4-5 minute recovery when performing this or any other apnea skill.

OK, Oops already...

Forgot that the 25% for VR is actually of VC so it is really 20% of full breath volume without packing (VF?). So, to fix my 5M pool equation...

20% / 1.5ATA = 13.3333333% = 100% / 7.5ATA (or -65M)

Or, if skindiver has a VC of 8L then to generalize his VR is 2L for a total of 10L without packing. Not to be confused with his reported VC+Packing of 10L (Vmax? = 12L) so:

10L/7.5ATA = 2L/1.5ATA = 1.3L

Is this right? A VR only dive to -5M gives the same lung feel as -65M on a full breath without packing. Not sure if I should doubt my math or if we should all feel good about doing negatives to any depth over 2M... Speaking of which what does that make my backyard pool equal to...

20%/1.2ATA = 16.6666666% = 100%/6ATA (or -50M)

OK, someone tell me I'm doing something wrong here. I know we are only speaking of the volume of air in the lungs after compression, or the feeling it results in. But still, this seems to be, well a bit extreme.

Lets see, if you could reverse pack yourself down to 15% of VF, and extra half liter for skindivers numbers... That would put a mere -2M as being equivalent to... -70M on a full breath. The math works but I don't want to believe it. Of course that would explain the utter failure in trying to equalize the one time I tried that in my pool.

numbers

Hey Ed
Your numbers are good. There are however, a few gottcha's.
Did you exhale to Vr and empty your mouth? Big difference.
Feet first is way easier.
Very few divers can make it with no air loss.
Don't forget the mask too.
With practice the coughing thing gets better, slowly.

>is there a typical percent of RV that can be removed by reverse packing? I don't have access to a spirometer so I can't test myself. Just wondering what can we really simulate in a 5M pool with reverse packing.

If you exhale to Vr, lie on your back in the shallow end and reverse pack into a 1L bottle, you can get a very good idea. The best I can do is reverse 35% of my Vr.
By clipping air filled bottles to a belt and letting out just enough to sink (use lead if you have to), you can measure any change in lung volume easily.
Aloha
Bill

Makes sense...

I was thinking about the air in the mouth after my last post. It did seem like that would make a big difference. A mouthful of air compressed by 2-5M in a pool would still do a bit of equalizing. Where as if you have emptied your mouth as well then you have to get air to equalize by reverse packing or using other tricks I'm not yet familliar with. I know that feet first is easier. Found that one out fist hand long before I knew what I was doing had a name.

I like the bottle idea, though my wife will look at me strange. All I need now is to get a few bottles...