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FRC - I don't get it

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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FRC dives (Functional Residual Capacity), pretty much like diving after a passive exhale, where your lungs are at their "passive relaxed state". There are many benefits for training with this type of diving. First, it feels really really nice and relaxing. I know it sounds counter-intuitive but it's true, personally I enjoy my FRC dives more than my full-lungs dives. Part of it is because you are less buoyant, so you have very little effort to do on the way down and will start free-falling very early, which helps a lot with relaxation. One of the main advantages for training, is that in an FRC dive you mimic all that happens in your body during a deep dive, without having to go so deep: the pressure on your lungs and chest, the equalization etc... With FRC dives to 20-30m you will mimic all the sensations that you will have to deal with, much much deeper on full lungs. So this is a great way to get your body used to the pressure, to work on equalization etc. And you can repeat many FRC dives to 25m, whereas if you go to 60 or 70m on full lungs you will do one dive and then you're exhausted. You also get very strong MDR (dive reflex) with FRCs, so they're also great as warm-up dives before going for a deep dive. And then exhale dives are also a great tool for spearfishing of UW photography in shallow water, instead of over-weighting yourself. How to do it? Personally, I take a normal big last breath, and then let some air out slowly (so I can control exactly how much I exhale), usually to the passive point, then hold and start the dive. But be careful, this type of dive can be dangerous if you don't do it properly, so at the beginning it should always be done under supervision of an experienced instructor who will explain how to do it properly.
 
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I don't get it. ..if FRC diving is the way too go for deeper and longer dives how come the pros don't do it? Never saw Trubridge dive FRC...

A lot of elite divers have dabbled with it but nobody really has been able to do any kind of record with it--Sebastian Murat was set to do a deep NLT dive that way but it didn't come together.

It can be a great training tool for understanding dive response and practicing EQ, and is pretty neat for skin diving but the more wetsuit you wear the less relevant it seems to get, unless you are diving really shallow in a heavy wetsuit and don't want to load up with weight. However for training and conditioning--both dry and wet--it is effective to get hypoxic in a hurry and work low O2 but not necessarily high CO2... I mix it in frequently to my dry training, less often in my wet training unless I am stuck in a very short pool. Good for warm-ups on a line as well....

It is worth noting that some divers get a radically stronger dive response with FRC vs full lung; in myself the enhanced response isn't dramatic enough to offset the lower starting O2.
 
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Stronger dive response is what makes diving frc so effective. Like ninja says, that varies among divers and there doesn't seem to be any way to find out how yours reacts without trying it. Mine seems to be sort of middling, which is enough to make frc diving fabulous for the kind of serial, moderate depth diving I do.
 
Does anyone use FRC/Exhale diving for uses besides deep equalization? For example recreational? Just to get better at it for the sake?
 
I've read a lot of interesting threads on here regarding FRC - many say that beginners should have an experienced guide because it is "dangerous".
Just exactly what is the danger? How about starting out at the deep end of a pool - is that also dangerous?
Thanks.
 
You can damage your lungs and / or trachea, you can sink too fast and be heavy coming up, you can inhale water easier...


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I've squeezed my trachea in a deep pool before on fully empty lung.


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apneaddict - you got squeezed in a pool on fully empty lungs or half full FRC lungs?
 
The deep end of the pool is a great place to explore(carefully) exhale diving, because it is so controllable. It is very possible to get squeezed on a full exhale in 4 meters, but go at it slow and you will develop the ability to feel a squeeze coming before it gets damaging. It can come fast, so take it slow and careful. With frequent practice, your lungs adapt and it gets more and more comfortable. Then you can (slowly) add reverse packing. All this adds to depth ability and safety in open water diving. I dive about half lung, often near my squeeze limit, but haven't been squeezed in years. Its all practice.

Stress on the "take it slow" It takes a while to adapt and to get the feel of how much exhale is too much.
 
...and use a float with a rope / bottom weight even in a pool to REALLY control your speed of descent.

One hand width at s time even...

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...and use a float with a rope / bottom weight even in a pool to REALLY control your speed of descent.

One hand width at s time even...

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Yes AA, I do the same.
I consider an empty lungs dive to -4 / -5 m like a FIM dive to 40-50m. Therefore I match the dive time, 1'20" - 1'40", to allow my body to gently cope with the stress, and the heart rate to go low with the pressure.
In order to be safe(r) I think you'll need to to avoid contractions, and avoid sudden jerky movements. So only gentle small, hand over hand pulls, and bi finning, avoiding stretching the chest, diaphragm, larix, trachea, etc too much, and getting injured. NO CNF armstrokes! Because of the dive time needed for empty lungs, the equalisation skill needed and the experience needed to subtle stretch but not break things, this is an advanced technique not suited for beginners.
 
I started training more frequently and do a couple passive exhale dives to 10m [with a short hang] followed by rescue dives with my buddy to get the dive reflex going. At the end of this weeks session I did some full exhale (completely empty but no reverse packing) to 8 and 10m - these weren't the most comfortable dives but I went slow to avoid any injury, what is the rough math on depth simulation with a full exhale dive? Thanks in advance for any help.
I have limited opportunities to do deep dives but the last time I did, I hit the bottom at 33m using VTO and it felt really relaxed and smooth. My recent full exhale dives as mentioned above were all using mouth fill (with mask, no nose clip) and i only stopped at 8m because i missed the EQ and for some reason opened my glotis and lost the mouth fill.
 
The math doesn't mean much. If it did, I could dive full lung to 60 0r 70 meters, but I can't come close to that. If you can do a full exhale to 10 meters, that is pretty deep. You may have little trouble with 40 + meters full lung, but everybody is different, so you will have to try it.
 
Assuming that your residual volume is 25% of your total lung capacity, empty lung dive to 10m should theoretically simulate a full lung dive (no packing) to 70m (or much deeper if your RV is low). Of course it doesn't mean that you can safely reach this depth. I gave you these numbers just to show that these shallow empty lung dives can be pretty dangerous. You're lucky you didn't get squeezed. You moved straight from 10m on passive exhale to 10m on empty lungs. That was a huge jump.
 
Second MarcinB. Your descriptions indicate you have a very flexible chest, but remember, exhale squeeze comes on very fast with little warning and you can get thoroughly squeezed doing the same dive you just did with no problems a few minutes before(personal experience). It can really screw up your diving for a long time .
 
Thanks for the response(s). I appreciate the detail regarding how easy it can be to push it too far and will be more aware in the future, thanks again.
I try to stretch a few times a week with reverse packing usually taking about 10minutes or so each time. Any good stretches and/or extra information you might recommend going forward?
 
I recommend uddiyana bandha while lying on the floor on your back (in addition to the standard position). In this position you will stretch also the abdominal wall, which in my opinion is as important as stretching the diaphragm.
 
I follow what Marcin does with the addition of intercostal stretches, which seem to make a huge difference in depth ability for me. Search "intercostal" and I think you will find a description.
 
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