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Exhale V Inhale diving

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.

Ben Gowland

Aplysia gowlandicus
Apr 4, 2002
A question of nomenclature:

When Seb first introduced FRV/FRC (Functional Residual Capacity/Volume) we called it 'FRV diving'. Since then it has metamorphosed into 'exhale diving'. I can see why this is of benefit, as it gets the point of the technique across quickly - rather than having to explain FRV every time.

However, it occurred to me that 'exhale' implies 'breathe-out and dive' whereas I exhale to RV ant then breathe in a bit before diving.

What do others do?
he's now started to use the phrase "exhale and sink"

i find i have to do a couple of practice breaths before diving to make sure i take down the right amount - not too much and not too little. if i exhale passively in water my lungs will totally empty.
i hold back on the exhale rather than inhaling - that's my method.
Its definitely hard to figure out how much to exhale, so I mainly use exhale dives for warmups and flexibility.
Jim - That's actually one fo the reasons I do it on inhale, rather than exhale. I find it easier to 'judge' where FRV is.

Ben that's a great idea. I was thinking about the lack of control of the amount retained yesterday as I was diving. It never dawned on me to use your method.
Erik Y.
I am a bit pussled.

Why are you guys doing this?

I understand you can avoid narcossis e t c with FRC diving - but that is only a risk after passing lets say 60 meters.

Do any of you dive that deep on FRC?

Does any of you dive deeper with FRC than with normal? If not - whats the point? whats your plan - tell me!

Sebastian /Sweden
The deepest I have gone on a half-lung is 27 meters and I really felt the pressure. I like it better than negatives because the lung compression is more gradual and controllable.
Even shallower than 60m, there are several uses for FRC dives:
- Much safer than negative pressure dives to induce blood shift
- Much reduced risk of decompression sickness during repetitive recreational dives
- Decreased muscle fatigue on repetitive dives due to dramatically decreased energy expenditure during the dives
- Faster recovery between dives due to less muscle exertion during the dive

You'll notice that upon surfacing from a recreational FRC dive, you recover very quickly, once again because you used much less energy during the dive (no energy to get down).

At Whytecliff in Vancouver, there is a great spot where there are giant cloud sponges at 53m-55m. However, on an inhale dive, you could do that about twice, with a long interval, and that's it, you're done for the day in terms of DCS risk. So the only solution is to learn to dive it FRC.

Eric Fattah
BC, Canada
re: exhale/inhale amount

For exhale dives, I do various amounts, depending on the goal of the dive. A lot of people seem to think they need to find one level/amount of exhale to be doing FRC, or maybe it is just an attempt at comparison.

Anyhow, it seems that importance should be based on finding some arbitrary lung volume that can be reproduced on successive dives, which achieves the goal of the dive you intended.

So, if you want to work on equalization, you might exhale passively (stay shallow and work on mouthfill). If you want to work on flexibility you might be half way between FRC and full inhale (go deeper with a gradual squeeze). So, whatever works for you and gives you the development you are looking for.
re: why bother

I use exhale dives to train for:

- deep diving flexibility; less dangerous than negative dives, due to more gradual lung volume change.

- deep diving equalization; less dangerous than repetitive dives to your max depth to have practical experience with equalizing techniques.

- blood shifting legs; less dangerous than repetitive dives to your max depth to acquire large blood shift and thereby give your legs a workout under those conditions.

- mental confidence; get used to the psychological issues that occur when you pass negative lung volume.
..and very enjoyable and more relaxing way to dive (my opinion), it's really worth trying.
I can understand how these exhale dives lessen the work required when descending, but wouldn't the workload be increased on the ascent?

Eric, did you dive without a suit at the WRC because you were doing an exhale dive? I was also surprised to see photos of you doing dynamic with a suit.

Beside Eric and Tyler have said, I do believe (don't have proof yet) that this type of diving can induce changes in the way oxygen is used in the diving muscles.
Because almost all the time, we are working in hypoxia, I think is possible to induce higher non pulmonary oxygen stores (including myoglobin concentration and conductance).
Also Bevan mention the haemoglobin raise.
Does it only seem to me that exhaling before diving leaves me calmer than exhaling to the full and then taking a specific small amount of air in?
My guess would be that if you dive after exhaling you should have higher blood pressure (good) and lower pulse (also good) then after a small inhale...
But I've barely done any exhale diving, can anyone support/disproof that?
I usually inhale deeply then exhale slightly for FRC dives. I find it feels better than inhaling a small amount. When doing FRC dives with no-suit, I think it is the most pleasurable way to dive. My longest FRC dive was 1'44" to 41m, so there is still time to spend down there.

Eric Fattah
BC, Canada

The workload would be slightly increased, but at depth if you have gone through vasoconstriction, then the power required to deal with this, is not using up much of your O2 from your blood.

However, if you did not vasoconstrict, then... oh oh! ;) This just means you will find you have a shallower limit. Or you may have to lighten you weight to something more manageable, although you then will lose some of the benefits of the exhale dive.