Reverse packing just before a dive?

[growingupninja]

More or less. The direct O2 gain is rather minimal, and as Eric wrote, the loss due to the muscular effort may be in fact bigger.

Larger, deeper breaths also raise HR, at least in my case. I use a couple purge breaths and deep breaths after surfacing (after hook) as part of recovery when spearfishing or doing challenging pool sets, but prior to actually dropping breathe very minimally. My best dives/holds always begin with my HR low and I think myself to as relaxed a state as possible...

I think the 'breathing' part of breatheup is a myth but not the relaxing part... Although starting from a rested state the relaxing part only takes seconds.

 

[azapa]

I once watched a seal for a long long time, just tooling around near a fishing warf. It never noticeably breathed, packed or did any other strange stuff. They just go under the water and swim. Millions of years of evolution has of course helped them a little, but I often have that seal in my head when I am preparing for a dive.

 

[FreeRestriction]

I once watched a seal for a long long time, just tooling around near a fishing warf. It never noticeably breathed, packed or did any other strange stuff. They just go under the water and swim. Millions of years of evolution has of course helped them a little, but I often have that seal in my head when I am preparing for a dive.

Thats a great point. Ive never seen a seal hyperventilate before a dive. But man would that be funny to see. But then again ive never seen a seal pinch his nose in order to equalize either.

This brings up another thought. I wonder if and how often a seal or other aquatic mammal blacks out and dies. Im sure it happens under stress like when a great whites after a seal or when a new born whale has been harrassed by killer whales so much that its too weak to get to the surface to breath.

 

[azapa]

whales and seals more often die from DCS than blackouts, from what I have read. A fright, or marine sonar, explosions etc will scare them and they surface too quick.

 

[FreeRestriction]

whales and seals more often die from DCS than blackouts, from what I have read. A fright, or marine sonar, explosions etc will scare them and they surface too quick.

I didnt even think about that. Do they know they must make their ascent slowly? Or are they more resistant to it to begin with so unless racing to the surface their fine.

 

[growingupninja]

whales and seals more often die from DCS than blackouts, from what I have read. A fright, or marine sonar, explosions etc will scare them and they surface too quick.

I read somewhere (the link was probably on this site!) that marine mammals, in all the autopsies performed on them, never actually drown either, in the medical sense--water in the lungs killing them. They always suffocate; water does not enter their lungs until after their heart has stopped beating. In humans it is the opposite--water enters the lung before death and causes the death. Morbid but interesting.

I remember watching a large seal for a while in the kelp; he was very close and we were both studying each other. He hung at surface, nose an inch out of the water then after a while exhaled and dropped vertically under the surface. So easy for him. I hunt/dive frc in when in heavy shallow kelp now..

 

[baiyoke]

I think the 'breathing' part of breatheup is a myth but not the relaxing part... Although starting from a rested state the relaxing part only takes seconds.

So the-secret-ninja-O2-overinducing-breathup might be a "myth".

But still, the connection between breathing and relaxation is well established from meditation, yoga etc. etc.... and that relaxation-mindgame is still a tricky thing, even if the more scientific O2/co2 calculation is more clear...

So breathup might be more, as you say, about relxation...

For me it is relaxing to do the long exhale... But it might be that it is possible to enter a very relaxed state from... very normal relaxed breathing... perhaps with lots og yoga and meditation it is possible to enter a relaxed state quickly and from normal breathing...

OR is even the relaxation part also overrated in a sport that needs awareness and activity ... perhaps all you need is absence of tension and distracting thoughts, but not a "trance" state of mind... Is it that "simple" (I know absence of tension and distracting thoughts might still be difficult)..? Or might there still be a huge O2-conserving benefit from a special state of mind..?

Hope it's not hijacking the thread...

 

[FreeRestriction]

So the-secret-ninja-O2-overinducing-breathup might be a "myth".

But still, the connection between breathing and relaxation is well established from meditation, yoga etc. etc.... and that relaxation-mindgame is still a tricky thing, even if the more scientific O2/co2 calculation is more clear...

So breathup might be more, as you say, about relxation...

For me it is relaxing to do the long exhale... But it might be that it is possible to enter a very relaxed state from... very normal relaxed breathing... perhaps with lots og yoga and meditation it is possible to enter a relaxed state quickly and from normal breathing...

OR is even the relaxation part also overrated in a sport that needs awareness and activity ... perhaps all you need is absence of tension and distracting thoughts, but not a "trance" state of mind... Is it that "simple" (I know absence of tension and distracting thoughts might still be difficult)..? Or might there still be a huge O2-conserving benefit from a special state of mind..?

Hope it's not hijacking the thread...

No deffinatly not hijacking the thread. This is a great turn in the coversation. For me im able to get in to a trance like state pretty easily with normal breathing. I think that trance makes me more "numb" to what happens to me and around me and i think that leads to a longer breath hold.

 

[alonrivkind]

Baiyoke, you right about the connection of long exhale with relaxation-it work for me as well. but when you are in a deep state of meditation or corps pose relaxation the breathing is 'sub-neutral' .
It happens for me many times while maditation that i dident felt any movment of breathing in or out but i was not holding my breath.

 

[Siku]

OR is even the relaxation part also overrated in a sport that needs awareness and activity ... perhaps all you need is absence of tension and distracting thoughts, but not a "trance" state of mind...

I remember Trux saying, in a thread about heart rate, that a low heart rate was great DURING the dive but not necessarily helpful BEFORE. So extended exhales (which stimulate the vagus nerve and reduce heart rate) may not be the way to go.

Apologies if I got that wrong Trux.

 

[growingupninja]

So the-secret-ninja-O2-overinducing-breathup might be a "myth".

But still, the connection between breathing and relaxation is well established from meditation, yoga etc. etc.... and that relaxation-mindgame is still a tricky thing, even if the more scientific O2/co2 calculation is more clear...

So breathup might be more, as you say, about relxation...

For me it is relaxing to do the long exhale... But it might be that it is possible to enter a very relaxed state from... very normal relaxed breathing... perhaps with lots og yoga and meditation it is possible to enter a relaxed state quickly and from normal breathing...

OR is even the relaxation part also overrated in a sport that needs awareness and activity ... perhaps all you need is absence of tension and distracting thoughts, but not a "trance" state of mind... Is it that "simple" (I know absence of tension and distracting thoughts might still be difficult)..? Or might there still be a huge O2-conserving benefit from a special state of mind..?

Hope it's not hijacking the thread...

Well I can't speak to the yoga meditation thing as I am a decidely non yogic freediver with a background in competive swimming and ringsports, although many stretches I do have similarities and the diaphramic forced exhale/grunt that I was taught to use with most every combat movement (and did hundreds of times nearly everyday for years) seems to be almost identical to some common freediver/yoga breathing exercises.

I suppose it is whatever you can do to slow your HR; if a long exhale works then that is great. For me unless I am panting from serial effort then any large breaths before a dive will be very slow--final inhale takes about 10 seconds (I don't pack). When I have practiced with a HR monitor on dry land, when I concentrate on relaxing and going to the specific mental place that I go to prior to a deep long dive (it feels like I am focusing on a spot 2" behind my left eye), it takes about 15 seconds for my HR to drop a few beats below very relaxed resting--from about 55-56 to 52. I am not paying specific attention to my breathing at this time although breaths are very, very shalow. It is not much of a drop but it goes right back up if I break focus or take fast breaths. When I feel like I am at that point I do my final slow inhale and start the dive.

If I start from this state, EVERYTHING is better--more bottom time, less hypoxia, more comfort. From practicing on dry land with an O2 meter I have learned that comfort absolutely does not equal less hypoxia, but this kind of state when I can get there, helps me.

Long post but point is that for me a mental proccess to lower HR is more important than breathing but for some a relaxed state and low HR seems to be accomplished by a specific kind of breathing.

 

[trux]

I remember Trux saying, in a thread about heart rate, that a low heart rate was great DURING the dive but not necessarily helpful BEFORE. So extended exhales (which stimulate the vagus nerve and reduce heart rate) may not be the way to go.

Apologies if I got that wrong Trux.

Yes, I use to write it often, though orginally it was certainly either Eric Fattah or Sebastien Murat who posted similar comment a long time before me. Yes, the high rate before the dive helps oxygenating the blood and tissue.

I just learned from Sebastians bloggers that the HR of a stationary Grey Seal on the surface is 140 bpm, and 10 bpm at a 100m+ dive, and it makes perfect sense.

 

[chrismar]

whales and seals more often die from DCS than blackouts, from what I have read. A fright, or marine sonar, explosions etc will scare them and they surface too quick.

Unlike us, marine mammals don't black out. Essentially, blacking out is a continuation of what we call the MDR, but I think of just as a survival reflex. The last step is switching off the concious brain.

Marine mammals instead stay concious, but suffer brain damage. The trade-off, I guess, is that a seal is unlikely to be rescued by another seal so there's no point in prolonging the apnea time if the animal cannot save itself. Either because we've never adapted to this or because our social structure means we saved people who were blacked out but the brain-damaged did not reproduce, we prevent brain damage and switch off the brain much earlier than we have to. Thank goodness, otherwise things would go very badly for all of us!

 

[growingupninja]

Y

Yes, I use to write it often, though orginally it was certainly either Eric Fattah or Sebastien Murat who posted similar comment a long time before me. Yes, the high rate before the dive helps oxygenating the blood and tissue.

I just learned from Sebastians bloggers that the HR of a stationary Grey Seal on the surface is 140 bpm, and 10 bpm at a 100m+ dive, and it makes perfect sense.

This is highly counter to my own experience and I am obviously not a seal or world champion human.. High heart rate during the recovery period makes a great deal of biological sense since tissues need to be refreshed and body needs to vent; I am grateful that mine kicks in with a vengance when I begin to breathe again. But an elevated HR prior to diving, if the body is already saturated makes no biological sense to me. I could triple check with my O2 meter--and I know it has failings-- but comfort aside I am quite certain I never get better levels when I start a hold with an elevated pulse.

 

[growingupninja]

Interesting, this fluffly link
Seal Adaptations to Antarctic Conditions
Says that seals hyperventilate prior to diving and we all know they exhale... re: seal heartrate.

Actually just also read a pubmed that mentions that seals also tend to maintain consistent surface interval times but vary breathing pattern depending on length of dive. Kind of interesting and related.

 

[FreeRestriction]

Interesting, this fluffly link
Seal Adaptations to Antarctic Conditions
Says that seals hyperventilate prior to diving and we all know they exhale... re: seal heartrate.

Actually just also read a pubmed that mentions that seals also tend to maintain consistent surface interval times but vary breathing pattern depending on length of dive. Kind of interesting and related.

Interesting read. So why are seals hyperventilating and how is it beneficial to them where its not for humans?

Id love to read about what breathup techniques seals use for what type of dives.

Edit: thinking more on the HR idea. Wouldnt it make sense that a raised HR means the hearts just keeping up with the demand for oxygen and not actually increasing oxygen saturation. My point is if your HR is up so is oxygen demand. But in addition to only meeting the increased demand for oxygen if you then hold your breath your going to need to then reduce the demand to get the HR down. So it would seem to me that starting with a reduced HR is ideal. Unless im understanding wrong you cant just raise or lower HR on its own. A lower or raised HR is a response to the demand your body has for oxygen.

 

[growingupninja]

Interesting read. So why are seals hyperventilating and how is it beneficial to them where its not for humans?

Id love to read about what breathup techniques seals use for what type of dives.

Edit: thinking more on the HR idea. Wouldnt it make sense that a raised HR means the hearts just keeping up with the demand for oxygen and not actually increasing oxygen saturation. My point is if your HR is up so is oxygen demand. But in addition to only meeting the increased demand for oxygen if you then hold your breath your going to need to then reduce the demand to get the HR down. So it would seem to me that starting with a reduced HR is ideal. Unless im understanding wrong you cant just raise or lower HR on its own. A lower or raised HR is a response to the demand your body has for oxygen.

Well, their hemoglobin is very different than ours and they have a very different blood chemistry, so while there are parallels there are a lot of differences in our body systems and that of a seal's. The study abstract I read along with some other ones basically said that seals' breathing trigger is CO2 same as humans although they of course are tolerant to higher levels, and when doing serial dives their surface interval lasts just long enough to vent CO2. If they have a large CO2 build-up but maintain a constant surface time then after a long dive they are going to be breathing at a higher rate, same as a human does when doing interval swims. Similar to humans, they need much longer surface intervals if they are actually doing long dives where they are becoming hypoxic.

Interesting though one study noted that they of course experience slowing of the HR when diving, but when in open water, PRIOR to surfacing, on ascent their HR rises, presumably anticipating that first breath.

As for as voluntary control of HR in humans, it is possible to some degree in people with training... I guess I can kind of influence mine a microbit by relaxing and some yogi's have been proven to have great deal of control over theirs. That Hof guy that sits on blocks of ice naked raises his, without exertion, when he needs to maintain his body heat. 'Ordinary' people have been trained to influence theirs by biofeedback sessions. In the case of the Hof guy, I doubt he thinks about raising his, it's just a consequence of what he has trained himself to do. Probably same as with divers; I imagine trained divers probably lower their HR a little bit in anticipation of a dive but they aren't thinking about it. They're just preparing to dive and the lowered HR is consequence.

God bless Denea and her cookies and bikini I keep hearing about but although the grey seals have HR that have been measured up to 140bpm, that appears to be the high end from most studies I looked at.

 

[Siku]

Not exactly but close, due to the diffusion. And the level of CO2 in lungs stays pretty stable too. If you do a purge, the CO2 is very quickly replaced by the diffusion from the blood, so it comes back to almost the same level as before. You need to repeat the over-ventilation to sink the CO2 level also in the blood, allowing so a lower level of CO2 in lungs, and hence slightly higher O2 level, but it is then already serious hyperventilation with all its very negative consequences.

The worst is that the reverse packing is slow, so the CO2 level get equalized more than at a rapid purge, so in fact the reverse packing as a purge may have rather the opposite effect than you are looking for, and may not help getting any extra O2 into the lungs at all.

If I understand correctly, during exhalation (whether effected by diaphram or unpacking) the air in the lungs is not being refreshed. The
VOLUME of air in the lungs is changing while the composition of gasses is determined by the exchange in the alvioli, with no addition of fresh air. So an exhalation with unpacks would'nt extract any more CO2 from the blood than a similar duration but lower volume exhalation. In fact less, as the lower volume of air would mean that any amount of CO2 moving out of the blood stream would then represent a larger % of the total gasses in the lungs, and therefore a larger slowing of CO2 diffusion from the blood.

What it DOES do is expell more CO2 from the LUNGS (in absolute terms) altering the composition of the air in the lungs AFTER the next inhale (as a different % of the air in the lungs after that inhalation will be new air).

 

[Siku]

I seem to have contradicted Trux and... got away with it!

 

[trux]

Sorry, I didn not think it was necessary to answer, because I did not see any conflict there .

The volume of CO2 expelled from lungs is around five times higher than the volume of O2 you gain. The CO2 continues to difuse to lungs even when you exhale (also thanks to the increased transpulmonary pressure gradient). And the CO2 gets then extracted from the blood faster immediately after the inhale due to the stronger Haldane effect (more O2 causes the hemoglobin to release CO2 easier). So the CO2 level in lungs will soon reach the orginal level while sinking the level in the blood. The CO2 in lungs then does not grow much, most of it remains in the blood (and tissue), until the respiration starts again. The CO2 level in lungs is relatively stable, and changes less than the level in blood.

However, the volume of CO2 expelled during the single purge with reverse packs is certainly not any critical problem, and does not represent any serious risk of hyperventilation. That was not at all the point of my previous posts. The point was that the gain is relaively negligible, and the loss due to the time, effort and strain of the reverse packing may be in fact bigger.