FRC - I don't get it

[bengreen]

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...

 

[Kars]

For me the value of doing FRC is educational.
People do often not realise how much they can improve their dive's start. Most beginners have a poor 'breath-up', and a poor technique of getting to the glide phase. Due to this their bodies metabolism and stress are elevated, which will result in a (much) higher O2 consumption all the way through the dive. If you manage to take that Zen like low metabolism down with you, like you would on a static dive, you would save lots of energy and O2 getting down. Diving FRC eliminates the need for swimming down, and reduces the tension on the body of inhaling full and packing, this allows for a smooth, easy and low metabolism entry to the glide phase, which already starts from the surface.

 

[FreeDivingJake]

For me the value of doing FRC is educational.
People do often not realise how much they can improve their dive's start. Most beginners have a poor 'breath-up', and a poor technique of getting to the glide phase. Due to this their bodies metabolism and stress are elevated, which will result in a (much) higher O2 consumption all the way through the dive. If you manage to take that Zen like low metabolism down with you, like you would on a static dive, you would save lots of energy and O2 getting down. Diving FRC eliminates the need for swimming down, and reduces the tension on the body of inhaling full and packing, this allows for a smooth, easy and low metabolism entry to the glide phase, which already starts from the surface.

I've always been interesting in learning, but my dive times will probably drastically decrease from 2 minutes to who knows what. I'm also just getting back in the water a few month hiatus and it feels great to be back I just have to get my dive times back up there to 2+ minutes. My first day back was Friday and I was only doing 1:30-1:45. I expected that because I haven't dove in a while. How long did it take you to learn FRC? Have your dive times increased substantially? The only diver I know who uses FRC is cdavis and he seems to really enjoy the technique.

 

[cdavis]

Bengreen, Deeper dives is hard for normal folks diving exhale(variants of FRC), because you reach your normal equalization limit in much shallower water. Given practice, you can dive as deep unless you want to do record dives. As far as the "pros" not using FRC, Laminar and Eric Fattah are two of the best divers in the world. Last time I heard both were using FRC. Eric has done something like 85 m CW with that technique. I am nothing special and normally do 90-100 ft dives with it, have done more. IMHO the technique really shines in recreational serial diving. Longer dives is the norm, after you get used to the technique ( which takes some effort and time).

Connor

CW may be getting near its limits because of narcosis. FRC offers a way around narcosis problems, but nobody has yet figured out how do over 100 m with the technique

 

[TheBob]

Having found this thread in a search, I just have to add a comment on YAA (Yet Another Acronym) syndrome.

Many nontrivial human activities develop useful acronyms, but it is REALLY helpful to expand the acronym at least once in a given context. That would stop my raving mind from speculating... Fantastically Realistic Cinema? Field Rated Caviar?

So help me out here, guys... okay?

Bob

 

[Bill McIntyre]

I agree Bob.

 

[Apneaddict]

Functional Reserve Capacity.

 

[TheBob]

Thanks, Apneaddict.

Since its use in this thread sounded like a technique was being described, not a capacity, I looked it up on the net and found "Functional Residual Capacity." I'm guessing that "using FRC" means that some divers focus on increasing FRC, is that a correct interpretation? I found no references to techniques called FRC, with either translation of the acronym.

Lots of interesting stuff.

Bob

 

[Apneaddict]

It actually means diving with that level of air In your lungs.

Sort of like.... passive exhale diving.
Doesn't sound intuitive... But there is a place for it sometimes with more experienced divers.

It is arguably more dangerous than diving with full lungs... Especially for a novice and especially without a trained spotter / safety / buddy.

It makes equalization more difficult for the novice and weighting would need to be changed as well.

Interesting reading on the subject for sure. I haven't adopted it for regular diving or Spearfishing... Except in cases where it's shallow and I'm too buoyant or as a warm-up.

 

[TheBob]

Thanks. I did wonder about not taking as deep a breath when I was snorkeling and had to struggle to get/stay down to 15-20 feet. Fins were terrible, didn't help; that was before I read about the neutral buoyancy point. I'm looking forward to the feeling of passing that point, must be freaky the first time.

 

[Bill McIntyre]

Maybe Bob gets it, but I don't.

 

[Apneaddict]

My bad - residual, not reserve.

 

[TheBob]

I'm just inferring what seems like a plausible reason: When my lungs are expanded, the balloon is larger; just inhaling and exhaling I can feel my body rise and fall. Ergo, I was guessing that people do it to minimize buoyancy before they pass the normal 'neutral' point.

Perhaps one of the folks who apparently knows why some divers do this could confirm or correct my guess? Not that I mean to try it, just incorrigibly curious. ;-)

 

[Apneaddict]

Plus... Lower CO2 production... Plus less recovery time between dives (to have to purge CO2).

 

[cdavis]

FRC's official definition is the above, equal to the amount of air you have above the minimum when you simply relax and open your throat. Its a lousy way to define a stye of diving because FRC as a percentage of total lung volume varies so much between divers, for me its almost empty, for others it can be 40%. To dive FRC means to dive with substantially less than a lung full of air. Mostly that means just above or just below 50%. Some folks have the chest flexibility to go much lower. The advantage of FRC diving is a stronger, faster diver reflex and much less energy expenditure(due to lower buoyancy) during the first part of the dive(where the diver is burning O2 almost entirely). Energy expenditure later in the dive is much more anaerobic, O2 is conserved in the core for use of the brain. the disadvantage is depth limitation(for most divers). The bottom line is longer, safer, more comfortable dives during recreational, serial diving in reasonable depths, if you do it right. That takes practice.

I use the technique for pretty much all of my diving, depth to 100 ft, time to just over 2 minutes when I'm diving a lot.

 

[bengreen]

I don't know, I like my air. I don't see how you can have a nice and enjoyable dive on almost empty lungs, but that's just me.

 

[cdavis]

I got to admit, it is counter-intuitive as heck, sure doesn't sound right. However, analyze the logic/physiology and it makes sense. Try it and it works very well.

Almost empty is not what most people do, 40-60 percent is more normal. I can't do almost empty either.

 

[TheBob]

This is fascinating stuff; once I have a chance to get in the water on a regular basis, especially if I get a chance to dive with someone more experienced, I hope I have a chance to try this technique, just for the understanding if nothing else.

I don't want to distract from the primary thread topic too much (maybe I'll post a new thread on this), but has anyone read Breatheology? That's next on my reading list, no idea if he includes a discussion of 'FRC technique' in his discussions on physiology.

Bob

 

[bengreen]

So with FRC do you take a full inhale then exhale some of the air and hold, or just do a more shallow inhale and go?

I read Breatheology and it has some great info, but goes a bit too deep into Yoga and stuff like that. Don't recall any mention of FRC in there.

 

[cdavis]

You can do either. Most divers start out exhaling cause that seems easier, then progressing to inhaling less than full. I think inhaling is better.