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depth adaption

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Aug 17, 2002
hi everybody

i´m pretty much a scuba diver and instructor for more than 10 years but since last year i´m in the process of shifting my underwater interests to more and more freediving. i´m sure you all understand why.

one of those hundreds of questions i have is this: my understanding of the safe depth limit for the avarage lung (let´s say 6 liters total, 1.5 liters residual) is 30 meters since at 4 bar surrounding waterpressure the lung will be compressed to it´s residual volume i.e. complete exhale.

now for me, since i´m the average dude, this is where it becomes important. i started using packing as a technique to help me equalise at depths below 30. this is very obvious since i increase my lungvolume before descending.

now i also have read some articles about bloodshift (increase of bloodvolume into the lungs) and the abdominal diaphragm which, if flexible enough, pushes upwards to a more or lesser degree.

i would like to receive some information on how this adaption process works, what kind of training is useful, how long does that take and of course where are the risks. also any personal examples might be interesting as well as any links.

i´m pretty much a fun freediver but i do enjoy going deeper also. increasing my cruising depths is a permanent ambition of mine and it keeps me trainig and not becoming too lazy.
fortunately i work as an instructor (for a living) for a great part of the year and get to freedive quite a lot on days off or mornings.

thanx already to those who are willing to spend some time and share some information.

keep cruising

If that limit bothers you, I have a simple experiment. First the lung volume should be 6L total, 4.8 vital and 1.2 residual(or other numbers but same proportion) and the dive to residual without a mask becomes 40 meters for a normal person and a perfect dive.
Find a good safety, do your best breathe up and start with water depth about two meters so you don't blow an eardrum. Take a deep breath, lie face down, hold on to a float and exhale as much as possible for 10 seconds. Then slowly sink to the bottom.
By going 1A to 1.2A you are simulating the part of a dive from 40-45 meters very closely. If you can equalize (Eric's method works well), you will be able to go to 5 meters plus, where the air in your lungs is down to 0.8L or 66% of residual.
Be safe, be careful, go slow and remember when you hurt yourself at this game, it may not show up for hours.

Hi Roland,
As Bill said, performing half or empty lung dives will help you improve the chest stiffness. Personally, I don't believe in lung volumes. That will not affect your depth. The blood-shift is an adaptation to achieve deeper depths. When you are going down there is a lot of pressure around you and the whole body is affected (mainly the air cavities as lungs, sinuses, stomach, etc) but the rib cage is rigid and at some depht the thoracic cage can get more compressed, from that moment the thorax became "more negative" than the rest of the body and the blood flow is re-directed to the pulmonary circulation. The pulmonary circulation is made of capacitance vessel (arteries that can hold a lot of blood) and the thorax is now more "liquid" so less compressible, thats why the feared lung colapse is just an anecdotal thing. Besides the vasoconstriction (narrowing of arteries) product of the diving reflex, sends the blood flow centrally (heart and brain) improving also the bloodshift.
If you are nearby the sea and have a good freediving parter you can practice at actual depth (is more fun), and you can try some hangins (more dangerous) with a good safety freediver with you.
The empty lung practices work well too, and are less extrenous than a dive to actual depth so you can practice it before trying a deep freedive mainly to get expertise with equalizing techniques.
Thats what I do, but when I was living near the sea I always practice within. The sea is our porpose, so make use of it.
Hang 10!

I think I think I recognise Herr Roland as the "Dodgy Bloke" ;) that I met and dived with for 3 weeks in Egypt!
If that is you Roland, thanks for the good times and help....come for a visit sometime :)
Erik Y.
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