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Empty Lung dives

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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New Member
Dec 6, 2002
Hi, I read in some of the posts around the forum where divers practice using 'empty lung dives' What does this help?
It helps you:

learn to equalise at depth
Stretch your diaphragm
stretch the capilliaries in your lung tissue (for blood shift)

Anything else anyone?

Dangers of empty lung dives?

Everytime I have read something about this, someone has mentioned that it can be very dangerous.

Can someone tell me what are the specific dangers of empty lung dives? Blackout is obviously one, but are there others?
What about lung squeeze, for example?
Black-out risk?... providing you don't hang about at depth, the risks are very small. There is much more risk of lung injury in my opinion. The rules that I follow are these:

don't stay at depth on an empty lung
turn around if the pressure feels uncomfortable
turn around if you fail to equalise (never bend your ear drums!)
only do empty lung dives along a line

My empty lung dives take about 25-30seconds down to about 10-12m. Gentle slow pull down and back up at normal speed. I could go deeper but it's just not necessary. (If I was diving over 100m+ on the sled, then I would probably go deeper to simulate greater depths.)

For me the main benefit is flexing the diaphragm and rib cage. (Empty lung dives do nothing for equalisation if you use the mouth fill technique. Your ability to equalise depends on the amount of air in your mouth, and nothing else. It is a good exercise if you use any other method though.)

just noticed this thread is in freedive hunting.... probably should be moved to the training/techniques section?

wrong section - sorry!

realized it just after I posted:duh Your answers helpful though! thanks
Since this was put in the Hunting/Photography section, I'll put in my dos pesos...

We never really do "empty lung" dives, but many times we descend w/o fully inhaling so that we're negatively bouyant at shallower depths. This is so that we can get down to a target w/o spooking it. Many times, an aggressive dive will scare fish, but if you just sink down to them w/o really moving, it helps. This mainly occurs when your prey is shallow or is coming in to investigate.

Benefits & Dangers

First of all, I strongly recommend against doing a spearfishing dive without a full lungfull. I know a diver who died while trying that, because he simply started the dive with less O2 than usual, and blacked out.

In addition to the benefits of negatives already mentioned, there are two additional benefits:
1. A negative dive is a fast way to initiate the diving reflex, faster than repetitive inhale dives (in this way it is often used as a 'prep' for deeper dives)
2. According to Mayol's cryptic writings (and my own experience), doing frequent negatives can amplify your maximal diving reflex, as well as accelerate the onset of your natural diving reflex (even without negative dive stimulation).

For example, Mayol, who did many long 'hangs' around 80m, noticed that during a scientific experiment, his diving reflex was both faster to initiate, and stronger, than the 'ama' divers he was compared to, even though they had been diving for many more years. He attributed his more powerful / faster diving reflex to the repetitive crushing of his rib cage & bloodshift during the many 80m hangs.

Hanging at 80m is dangerous for other reasons, DCS included, so hopefully we can achieve the same benefits by just doing shallow negatives.

Yet, there is a great danger of lung tissue damage, so always go extremely gradually and if you experience pain or cough blood or fluid, see a doctor and take weeks to recover.

Eric Fattah
BC, Canada
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