FRC Diving

[flyboy748]

I have started FRC diving (or at least what I thought was FRC!) recently. I start with a strong exhale, leaving myself feeling negitive lung pressure at the surface. If what I understand now about FRC (thanks Peter!) is correct, what I'm doing is less than FRC, somewhere between FRC and RV maybe? I start with a mouthful at the surface for equalizing. So far I haven't been past 30'/9m, however I have been strongly cautioned to be careful with this type of diving. I understand the need to dive with a buddy, but what else should I be careful of? If someone could provide me with an explanition of what I should be doing to continue safe practice of this type, it would be most appreciated!

So far I have experienced the throat pressure from an inadequate mouthfill and subsequent lack of air to equalize, (at which point I turn) but no other problems. I am doing this diving with a mask as well which obviously limits my depth as well due to mask equalizing.

I will be attending a Performance Freediving course in the spring at which time I expect I'll learn much more on this topic, but in the meantime I want to practice safely.

Thanks!
Aaron

 

[Bill]

Aaron
That's the way I've been doing negatives for over a year. You are simulating the part of a dive from approx. 30-60 meters.
With empty lungs, things happen 4-5 times as fast so, one meter is a large step. If it hurts or feels different in any way, stop and return to the surface to plan the next one with a clear head. If you don't dive every week, don't try your 'normal' depth without a warm up.
Just my thoughts.
Bill

 

[flyboy748]

Excellent advice Bill, thanks. Usually I start by hanging off my line at around 4-6m for the first, then progress from there. I have been diving at least once a week, but alot of the time I dive solo and I never do negatives solo. So I'll always start shallow.

Do you weight differently for negitives? I'm thinking I should, but I sure love the easy surface dive!

Thanks again

Aaron

 

[Lewis Matthews]

Hi all, thanks for the read anyone know good preparation to avoid lung/trachea squeeze? i know it depends on how much air you exhale but can i do something before hand, lung stretching? thanks

 

[cdavis]

Give us some idea of your level of experience and what exactly you are trying to accomplish. Also, check the dates on some of the threads you are reading. Some of the info is fairly out of date.

Connor

 

[Lewis Matthews]

Sorry just looking for friendly advice, i'm wanting to dive below 50 feet on an exhale dive, i've been doing FRC for a few months and i'm hooked, i feel great until around 45 feet, it doesn't hurt but feels a little tight, a strange sensation i've never experienced before, is it safe to progress slowly deeper? if your still interested in replying that would be fantastic

 

[cdavis]

No sorry needed. It's easier to help with more information. Glad you like it. I'm a strong fan as well.

Below 50 is a reasonable goal, here's how to get there.

Limit your exhale to half a lungful. That alone should get you near your goal.

Stretch at least 4 times a week, everyday is much better. Diaphragm stretches and especially intercostal stretches(full breath, hands together as high above the head as you can get, bend sideways and feel your ribs and waist stretch). These allow your chest cavity to get smaller during a dive with less strain or feeling of pressure. Be a little careful with both these exercises. Avoid reverse packing with diaphragm stretches until much later. Also, too energetic intercostal stretching can pull muscles (personal experience). Unless you are diving a whole lot, stretching is critical. I can't say exactly how it will affect you, but it keeps me in shape for 80 + even when I'm not diving at all.

Dive a lot.

Once it starts to get tight, rise a few feet till it doesn't feel tight, pause for 10-15 seconds and relax. Then you can probably go deeper without strain. Exhale diving means going slow, especially slow descents. It give blood shift a chance to fill part of your lung capillaries, allowing you to go deeper. Also, blood shift during exhale diving is cumulative over a series of dives. It allows you to go deeper as the dive session goes along. I think its also a big factor in allowing the longer breath holds that are typical of exhale diving.

When it starts to feel tight, you are still above the depth where lung or air passage damage can occur, but squeeze things happen very fast in exhale diving and with little warning. Go slow and don't push things.

Key thing to remember. You are diving with half the normal O2 store in your lungs. You must make the first part of the dive as near a static as possible to give your dive reflex time to kick in hard. Otherwise you are just diving with half your oxygen.

Weight yourself so that you are neutral shallower than full lung diving. For diving30-100 ft, I weight to be neutral about 12 - 15 ft. A surface dive and two lazy soft kicks and I'm drifting downward. don't move again till I'm near the bottom.

Connor

 

[Lewis Matthews]

Thank you so much Connor, this is exactly the advice i've been hunting down for months now, many thanks indeed, just one more question if thats alright, how do you know when blood shift is underway? Im unsure if i've ever experienced it before. Cheers

 

[cdavis]

Thank you so much Connor, this is exactly the advice i've been hunting down for months now, many thanks indeed, just one more question if thats alright, how do you know when blood shift is underway? Im unsure if i've ever experienced it before. Cheers

The pleasure is mine, ask away. Can't give you a definite answer on what blood shifty feels like; its too variable, but you have experienced it. We all do. I get quite noticeable tingles in my hands on deep dives. During dry diaphragm stretches, I can feel slight "empty" feeling in my legs and arms near at the end of the breath hold. When I start breathing again, I can feel the blood rushing back into my limbs. Some divers report much more obvious symptoms, blood draining from the limbs, rushing back in, etc.

Dive reflex(blood shift) is trainable. The more you incite the response, the stronger and quicker it comes on. There is also a genetic component. Some divers just don't have as much DR as others. If you find exhale diving to feel good and be rewarding, your DR is probably pretty good. Its something you need to know. Divers with poor DR don't get much out of exhale diving, it will even hurt performance and safety.

It goes without saying, dive with a buddy, especially when you are exploring exhale diving.

Have you seen the various exhale diving threads? Lots of good info in them.

Connor

 

[Lewis Matthews]

Cheers, thanks for you help Conner, much appreciated