What is FRC?

[dannyor]

I notice this term is being used here and there. Looking for on Wikipedia I found 'Functional Residual Capacity' which is the volume of air present in the lungs at the end of passive expiration. But then I find it here in phrases such as 'If you dive FRC'. What is diving FRC?

Thanks

 

[3xpr1ment]

Hi dannyor

Diving FRC: at the end of a passive expiration (with the lung almost empty) you hold your breath and dive.

There is a huge thread about it
http://forums.deeperblue.com/general-freediving/78598-exhale-diving-average-diver.html

Moreover the search function gives a lot of results.

 

[dannyor]

Wow!
Thanks
Read it. Really interesting ...
I'm used to massive lung packing, I guess that besides what is said in that thread the muscle tension to hold the lungs like that burns oxygen too.

 

[cdavis]

Diving FRC is often a little misleading. Some guys do dive at FRC, but diving exhale is probably a better description. FRC has a specific definition, but the volume it represents can vary hugely with the diver. Eric F dives with about a liter over FRC, but with his lungs, that is as much as mine full lung. My exhale diving is done at about 60-65 % of a lung full. My FRC in the water is almost empty. Trying to dive at that level would constrain my depth too much.

The advantages of exhale diving are two fold. 1. it is much more 02 efficient, takes much less energy to get down and roughly the same to get up, is way more relaxed, etc. Further, it rearranges the timing of energy expenditure during the dive so you are not producing much c02 until after your dive reflex has kicked in. 2. exhale kicks in your dive reflex early and strong, conserving 02 in general, particularly conserving 02 in the core and keeping the c02 building in the legs from getting to the sensors in the core, so more 02 to the brain and less c02 in the core to make you uncomfortable: longer, safer, more comfortable dives.

Fair warning, it takes a bit of practice.

Connor

 

[dannyor]

Hi Connor.
Thanks for the highly informative reply.
FRC sounds like something I would like to try.
My practice sessions are composed of statics, apnea walks, pool dynamic sessions and ocean. The order I wrote them also represents how frequent I do them.
What I understood from the thread that 3xpr1ment gave link to is that in the end, one has to put it to action in 'real' deep dives. However, since I cannot go to the ocean on a daily basis, do you know if there are things that I can do in statics/walks/pool to prepare myself?

Thanks

Daniel

 

[efattah]

Just be extremely careful, since if you try FRC apnea (even in the pool, or statics), it is WAY easier to black out. The sensations and warnings are totally different.

 

[dannyor]

Thanks Eric
I appreciate your comment

 

[Eran]

In addition, FRC dives increas the risk of lung or trachea squeez, as the pressure changes are extremely fast, and as metioned here by Eric make sure you are real carefull with these dives...
If you do them right, its a great way to train for deep dives, with out the logistics of deep dives...

 

[cdavis]

The "bit of practice" I refer to has two aspects: 1 Diving exhale feels totally different from full lung diving, it takes time to figure out what it should feel like. At first, exhales near full can be dangerous, as mentioned above, especially full forced exhales with reverse packing. Further, depth range is constrained and you can get squeezed easy(personal experience), even in the pool. Warning signs are easy to miss. 2. The body makes physiological changes when subjected to exhale diving. It takes a lot of time to adjust and get the full benefit of exhale.

The key is practice a lot and explore the technique, work into it slow. "real" deep dives are unnecessary and probably counter productive if done too soon. IMHO, as a style of diving, exhale is best suited to relaxed recreational diving in medium depth. Its the ultimate "lazy man's" style. Depth comes, but its not the main point.

I found pool work, 2-3 days a week,to be very effective in building exhale diving capacity, as described in the referenced thread. Note the time scale of thread posts, it takes a while. Real diving is much faster.

Something I'm experimenting with. Try a series, 6 or 7, short(40-60 seconds?) dry statics with full, forced(but not extreme) exhale. Hold to the first contraction, until it gets uncomfortable but not much past(remember, this is the lazy man's way). What do your legs feel like? You should feel blood shift, blood leaving the legs on hold and partially coming back when breathing starts. How early in the hold does the feeling start? You should find that blood shift is cumulative, getting stronger over the series of holds.

This is a great way to shorten your warmup time when you get to the pool or in real diving. I think (could be wrong) that it also helps train dive reflex to come on faster and stronger. If you try it, let me know how it worked for you.

 

[cdavis]

Clarification: Real diving is very necessary to get the technique right. "Real deep" dives are not. The combination of frequent pool practice and occasional open water diving worked for me, its just slow.

Connor

 

[dannyor]

I already had two practices at pool, in the following weeks I'll try to keep steady 2-3 pool sessions and one ocean session.
Connor. You said that you used pool practice. If you don't mind I'd like your advice. I'm trying to figure out a training plan. What is a good way of introducing FRC into dynamic apnea?

I had several thoughts regarding my status. I have a rather good static for a beginner (4'30") but I feel that I don't know how to make same advancement at dynamic yet (~30m). I have sensed that my body is rather tense when moving and I'm working on relaxing muscles between the strokes.

BTW, thanks all for your valuable posts.
You guys really rock

 

[cdavis]

Danny: Your effort division between pool and open water should work great, I'm envious.

Dynamic on exhale: Dynamics for distance is something I'm not interested in, don't think I could do 30 m. My exhale diving and practice is focused on spending a long time down at a reasonable depth. So, I'm not a good one to give advice on that beyond the basics. Probably the best place to start is a simple static/dynamic. Static at about 1/2 lung(what is comfortable) until the first urge to breath, then start dynamic, come up when it feels like it. Re read the first post in the above thread. Your times and distances will grow nicely.

Look through the "average diver" thread and see who is doing more serious dynamic. Ktreloar comes to mind. He even gets the technique to work for underwater hockey. PM them an see what they say.

Connor

 

[Herup]

Hi Dannyor

Please allow me to point you to this little thread.

Personally I find FRC dynamic (kick'n'glide or sprint) introduced by a static, as Connor mentioned, until heart rate has dropped significantly a really beneficial way to work with the various dive responses.
You can try going without goggles and noseclip and go straight from the sauna to let yourself fall right in the pool without any previous preparation. This should get you the fastest possible HR drop during the initiating static (might feel a little tough in the beginning ;-) Please enjoy.

Very best regards
H!

 

[dannyor]

Hi Guys!
Following suggested threads led me to Kars video on exhale diving. Tried it in the pool this morning. This is so awesome! Connor, I followed your advice and started with 7x60 sec FRC. My body got more and more relaxed (That is the first 60 sec were tough at the end and the last ones were very relaxed). After that I was very relaxed and tried to do 'frog flow' like Kars. This is the direction I'm looking for. After ~2:40 the sensations of the body changed, I started to feel tinglings all over, And then I started to feel a bit dizzy (no contractions though) and remembered your warnings that the body signs change and got myself out.
Also I experienced my trachea get squished as you told me. I guess this will get better with practice.
I attempted my planned swimming session afterwards and thought the body would get out of this state. After 200m swim I understood that swimming and this state of relaxation do not mix well. 3 hours have passed since and I still feel the effect of it.

Thanks a lot ...

 

[cdavis]

Hi Danny,

You are doing great, but slow down a bit. Exhale really is tricky and you don't want to get squeezed. I'm assuming you train with a buddy.

Interesting your comment about swimming hard after exhale practice. I've
heard nobody else mention it, but the same thing happens to me. Normally when swimming for cardio, it only takes 3 laps or so to get my heart rate up to 75 % of max. After exhale practice, it may take 10 laps or more. Further, my short term heart rate sometimes does funny things when I start the cardio swim, skip a beat, beat twice at double speed, etc.

Connor

 

[dannyor]

Hi Connor.
Thank u for the concern. You are right.
Got the same input also from someone else, so I'm slowing down. I behave just like a child ... :t
I was told by a very experienced diver who's also savvy on exhale diving that since I'm a beginner I should focus on statics and dynamics and can do exhales on low depths (~2m) for fun, but not as a practice. Specifically, he mentioned the squeeze that you spoke of that at 5m+ exhales for the untrained may result in an injury. Now the question that I'm curious about is how the body gets used to that squeeze? Is there any preparation I can take in the coming months?

 

[Eran]

Just like any other tissue, your lungs and respiratory system need flexibility, on your day to day "dry"life there is no use for that, but once you need to compress your lungs to a third fourth or fifth their size, you need to do so gradually... The preparation you need is depth training, since you still have some way to go till you need special depth training, if I understood you right. you can keep training your normal statics and dynamics, and go for an open water session every 3-4 weeks, if you are working on your 30's to 40's. once you get there and can feel comfortable with these depths you will need FRC training in order to extend your depth, if you won't have the opportunity to dive on a weekly basis... the FRC gives you the chance to train for depth without actually going deep...

 

[cdavis]

Hi Danny,

For true, you are not the only one who wants to go to fast; I'm a prime candidate.

Again, I'm seeing different people defining exhale differently. Perfectly understandable, since there are lots of different applications and not enough precise words to describe what we are doing.

Full, forced exhales with or without reverse packing:
Not for real diving. You can definitely get squeezed in 5 m if you are doing full forced exhales. Full exhales are good for training equalization, speeding up your warmups, and maybe training depth. They require lots and lots of care and can really screw you up; BO is a danger if you are not familiar with how they feel. I do them, but very carefully. Some very good divers don't think they are a good idea ever.

Diving or training at FRC:
Many divers (me) have a low FRC volume and real diving at that level doesn't work very well. However, its great for pool training for depth and exhale diving adaption. This is what I am doing now. If your FRC volume is 40 percent or so of full lung, diving FRC can work in open water.

Diving at around half lung:
This is where I and lots of other exhale divers are during real diving. Diving exhale isn't about a particular amount of air in the lungs, its about exhaling enough to make the trip down as near a static as possible and having small enough lungs to allow blood shift and other dive reflex aspects to kick in early. Meet those two criteria and the more air volume the better. Learning to take down a slightly higher level of co2 than most divers do also greatly contributes to long safe dives.

How does the body get used to negative pressure (leads to squeeze): Damned if I know, it just does. I think it is a combination of increased ability to blood shift including growing thicker blood vessel walls in the lungs, increase flexibility of the diaphragm/rib cage, increased ability to relax the chest and ????

Prep: Diaphragm stretches seem to help a lot; do several short sessions every day. I think the suggestion of doing a series of short full exhale dry statics every day helps train dive reflex. Diving at FRC or slightly below in a 4-5 m pool is great training and avoids most of the ills associated with forced exhale dives. I do a lot of that, stopping at the first urge to breath when I've got no buddy. Doing static/dynamic practice at any depth helps get used to exhale feeling. If you can do those in the deep end, so much the better. Look again closely at the first page or two of the "average diver" thread.

 

[ktreloar]

hey guys thought i would just chuck in my 10 cents worth,

hey danny,

Connor hit the nail on the head, FRC diving has to be taken at a slow pace. If forced you can really do some damage to your lungs. When i dive in the ocean and i havent been diving depth for a while, the first couple of dives i do are really slow to allow my lungs to adapt to the pressure change. For example if im going past 25m on frc, i like to do a slow dive to 20m then do a couple of slow dives to 25m just let the body adjust. Another thing that will make a difference in your diving is learning Frenzel and the mouth fill technique.

Hey Connor,

hows your training going mate?
At the moment im mixing up my training, now im incorperating FRC static tables as well. As far as dynamics goes im aiming for a more 1:1 approach usually being a 1:30 static and a 1.30 dynamic (70-75m covered with short plastic fins). Im also including sessions where i just focus on relaxation and increasing the time before the first contraction (best is about 2:55).

cheers guys,

Kyle Treloar

 

[cdavis]

Hi ktreloar,

training goes erraticly. Having trouble getting me and my training partner at the pool at the same time. Lots of relax on the bottom at frc and come up just after the urge to breath(no buddy) I've shifted from trying for max time at 60 % inhale(never could quite break 4 minutes) to doing frc volume, trying to increase training effect. If laminar is right, lots of time in 4 m at frc or slightly less should help real diving. I'll find out Dec 19 at the Mud Puddle.
Your 2:55 is awesome. Do you feel much urge to breath before the first contraction? What level of inhale was that dive? Any idea how many liters that represents?

Connor