Training Dive Reflex, Why so little emphasis?

[cdavis]

Why is there so little emphasis on training Dive Reflex, particularly its most obviously beneficial part, blood shift? And how does one best train DR?

Its pretty clear that an early, strong DR is the key to long, safe, comfortable dives. Other things, technique, c02 tolerance, anerobic ability, cardio conditioning, relaxation, etc, are important around the edges, but the central characteristic we need as divers is a strong, early DR.

Rivers of ink have been spilled dicussing how to train periferal things, but very little about DR. Why? Is it lack of understanding? I don't think so, but maybe partly. Is it because DR is tricky to train and hard to measure training progress? Thats my guess, but no excuse of the lack of effort put into figuring out how to train DR.

Early strong DR is what allows FRC diving to provide longer, safer dives even though the diver is taking substantially less 02 down with him. Part of that is improved physics of the dive, but most of it is DR. I see no reason why the principles for improving DR that FRC diving demonstrates could not be adapted to the full lung diving that most divers do. Its just a case of figuring out how. Incorporation of this type of information into courses would hugely improve diving safety not to mention performance.

I train DR, but its all experimental and what I do probably isn't the best way to go about it. So, what do other divers do?

Your turn.

 

[Nathan Vinski]

The way I train bloodshift is with 20-25m RV repeats. I think that a significant level of collapse is required to really enduce it and FRC diving to 30 or even RV to 10m isn't enough. While those dives use blood shift, you need to push it to its maximum with "deep" rv stuff to really get a training effect. The limiting factor with this type of training is equalisation, which has to be almost perfect in order to get that deep with no air as well as to minimise squeeze risks and from what I've seen, most people can't manage the mouthfill well enough to get there on a full negative.

Bradycardia is theoretically trainable with a bowl of ice water, and I've have improvements while doing statics in cold water but I haven't measured an improvemt when I'm doing breatholds in normal water. My bradycardia only comes with bloodshift..

The other aspects of DR (spleen, decreased brainwaves function...) are too expensive to measure frequently which makes monitoring training quite hard.

 

[cdavis]

Do you see a noticeable training effect, i.e. you can feel bloodshift coming on earlier, faster, stronger?

 

[J Campbell]

I have never been aware of blood shift - how do you know when you have it? My heart sometimes slows, but not always. I guess I have a poor dive response.

 

[Nathan Vinski]

Do you see a noticeable training effect, i.e. you can feel bloodshift coming on earlier, faster, stronger?

I notice that I need less warmups to remove the sensation of chest pressure. So for example if I'm doing a 35m+ frc dive (relativly un trained) I'll need 2-3 rv dives to 10m/10m/15m before my FRC dive has zero chest pressure sensations. After a few session of 20m+ rv dives I have the same result (no chest pressure) after 1 rv to 15m. After 2-3 weeks of consistant RV diving i can do 20m+ rv dives on dive #1 or deep FRCs on dive #1.

on frc hangs at 20m, before training, I feel bloodshift occurring at around 1:45 dive time but with consistant rv dives I feel the bloodshift sensations at around 1:15.

 

[Nathan Vinski]

I have never been aware of blood shift - how do you know when you have it? My heart sometimes slows, but not always. I guess I have a poor dive response.

For me I feel blood shift in 2 ways; either the disappearance of chest pressure on deep exhale dives, or the sensation of heavy legs during exhale hangs at around 20m.

The first is more of the long term sensation of bloodshift while the seconds is the immediate (while it's happening) sensation.

 

[cdavis]

Divers experiance of blood shift varies a lot. Diving FRC makes it much easier to feel. Doing either deepish frc dives or empty holds dry, I can feel the blood leaving my arms and legs(a little) and my arms want to twitch. Start breathing and the blood returning to the limbs feels sort of like a tingle, don't have the right words to describe it, but its distinctive. My heart rate doesn't drop near as much as Nathan's. I also don't get near as much relief from chest pressure as he does. Both are probably reflective of differences in the strength of blood shift.

 

[cdavis]

"RV to 10m isn't enough"


Nathan, why do you think 10m at RV isn't enough for a good training effect. Granted everybody is different, but I don't think I could do 10m at RV; I'd get squeezed for sure even if I could equalize to that depth. Anywhere close and my blood shift would be substantial.

 

[J Campbell]

So, do you suppose I could experience blood shift at the bottom of a 13 foot pool - say by doing negatives?

 

[Nathan Vinski]

"RV to 10m isn't enough"


Nathan, why do you think 10m at RV isn't enough for a good training effect. Granted everybody is different, but I don't think I could do 10m at RV; I'd get squeezed for sure even if I could equalize to that depth. Anywhere close and my blood shift would be substantial.

@10m you will be at 1/2 rv which equates to about a 1/8 lung volume or a 70m inhale dive or 30m FRC dive (assuming RV=25% and FRC =50%).

While undertsatanding that there are some variations between people's natural flexibility, these depths are achievable quite easily without injury (assuming equalisation technique is perfect i.e.: disengaged diaphragm) it's really only Beyond those depths that bloodshift training would actually be necessary to improve your tolerance to collapse. From my understanding the lungs are already very tolerant to aviolar collapse and squeeze can be avoided as long as you aren't using your diaphragm to bring up air for EQ or having contractions. Significant bloodshift and it's training effect will come when you start to have more significant pulmonary collapse in the bronchi. That would occure beyond 1/2 RV more in the 1/3 rv range.

 

[cdavis]

Is this a question of degree? I'm not interested in 70 meter dives and have never been able to get to square one on mouthfil. I generally dive with as relaxed a diaphragm as possible, my Frenzel tends to bring up a little bit of air without diaphragm involvement. Still, 30 m is about my max on frc(50-60 percent of max). Even at that level, blood shift helps a lot. Multiple dives gets me deeper and deeper. Since I know blood shift is cumulative, I attribute the increasing depth to the shift. I'd like it to come on stronger and earlier, makes for longer, more comfy dives as well as more depth.

Mark, you should have substantial blood shift empty at 13 ft. Feeling it or not is another question, depends on you. Be very careful with negatives in the deep end, especially combined with reverse packs. Start slow and progress very slowly. Squeeze can come on so fast and unexpected that it will catch you. Also, BO on almost empty can be easier. A buddy is even more important than normal.

 

[A.Naish]

@10m you will be at 1/2 rv which equates to about a 1/8 lung volume or a 70m inhale dive or 30m FRC dive (assuming RV=25% and FRC =50%).

While undertsatanding that there are some variations between people's natural flexibility, these depths are achievable quite easily without injury (assuming equalisation technique is perfect i.e.: disengaged diaphragm) it's really only Beyond those depths that bloodshift training would actually be necessary to improve your tolerance to collapse. From my understanding the lungs are already very tolerant to aviolar collapse and squeeze can be avoided as long as you aren't using your diaphragm to bring up air for EQ or having contractions. Significant bloodshift and it's training effect will come when you start to have more significant pulmonary collapse in the bronchi. That would occure beyond 1/2 RV more in the 1/3 rv range.

I don't really know much about this topic but, what would happen if the contractions start during the blood shift? Correct me if im wrong anywhere. Im still pretty new here. And btw mind explaining blood shift in a bit detailed manner? Is it the movement of blood to the vital organs? Thanks in advance

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[Nathan Vinski]

Is this a question of degree? I'm not interested in 70 meter dives and have never been able to get to square one on mouthfil. I generally dive with as relaxed a diaphragm as possible, my Frenzel tends to bring up a little bit of air without diaphragm involvement. Still, 30 m is about my max on frc(50-60 percent of max). Even at that level, blood shift helps a lot. Multiple dives gets me deeper and deeper. Since I know blood shift is cumulative, I attribute the increasing depth to the shift. I'd like it to come on stronger and earlier, makes for longer, more comfy dives as well as more depth.

As I was saying, 30m FRC dives will use the bloodshift but the degree at which it's nessessary isn't enough to have a significant training effect. It like lifting weight. You wont get bigger muscles by lifting something that isn't near your maximum. If you want stronger, earlier, and faster bloodshift you will have to push your bloodshift further. RV dives are the easiest way to do this as you can do many very easily, but I still think you have to achieve significant pulmonary collapse before any training effect come into play. It's hard to find but Aaron Solomons has a (slightly boring) talk on YouTube about avoiding squeeze and training the blood shift. He starts his students off with 20m rv dives with mouthfill and end with them doing 20m rv without mouthfill.

 

[Nathan Vinski]

I don't really know much about this topic but, what would happen if the contractions start during the blood shift? Correct me if im wrong anywhere. Im still pretty new here. And btw mind explaining blood shift in a bit detailed manner? Is it the movement of blood to the vital organs? Thanks in advance

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When you get into the water your bodies heat conserving responses will cause vasoconstriction (tightening blood vessels) in the arms and legs to increase blood volume in the core (vital organs). This helps keep you warm. This gets stronger during freediving due to the mammalian dive response. At a certain point as your lungs shrink more and more blood will surround the pulmonary tissues acting as a "cushion" protecting them from the pressure. as you eventually shrink your lungs significantly past RV then the internal vacuum will actually pull more blood onto the surrounding tissues (this is where blood shift training effect really happens).

 

[hteas]

I believe that Eric F, as well as (?? European that started it?) in early discussions on frc stressed that it should be done without warmup, and without training. You just do it (and trade suffering for a fast blood shift). I never got interested in it because it always seemed to be one shot and you were basically done for the day. Eric suggested that training would dilute the blood shift effect by getting your body to acclimate to the sudden change and lowering the effect. Did I miss something?

 

[cdavis]

Yes
Divers can maximize DR with the "no warm" up approach. Just jump in and go for it. Seems to work pretty good for dynamic,but damned uncomfortable, not so good for depth. Like you, its not for me. Diving FRC is a different thing. Its designed for going down and being comfy(and safe) during the dive Blood shift is cumulative, gets better with sequential depth dives. Sounds imcompatible with what makes the "no warm up" approach work, but its really not, just gets there a different way that is compatible with sequential dives. IMHO, FRC works best for sequential diving in moderate depths.