Heart Rate monitor for Precise Decompression

[superstar]

You would use your heart rate monitor to determine how fast you can swim without hitting your lactate acid threshold and bonking. Very important for scuba divers because we are such highly trained and conditioned athletes. Whats next, EPO injections.

 

[1_T_Submariner]

Thanks everyone for the posts.

Dr. Deco Hope you had a good trip to and from Wales and thank you for your response.

 

[Dr Deco]

Hello All:

I did enjoy Wales. It was a lot like Seattle - rainy and overcast. Monday I leave for Turkey for a week.:14:

I suspect that bradycardia conserves blood to the CNS (and heart). It would be shunted away from muscle and connective tissues.

 

[DanLVolker]

The Galileo manual doesn’t give specifics on the science behind heart rate monitoring and their predictive algorithms but they point out that heart rate is used as a predictor of work load but that the Galileo computer can toggle between the highest of heart rate or respiration.

British Journal of Sports Medicine, Journal of Physiology Education, American Journal of Physiology, National Institutes of Health, and many others are very interested in how diving affects heart rate and how sympathetic/parasympathetic responses to diving affect blood flow and compartmental allocation. A significant amount of research has been dedicated to the lowering of heart rate during scuba diving (diving brachycardia) and how what effect this will have on the diver. Some studies also point to right ventricular increase in size (ventricular hypertrophy) and the implications therein.

I doubt UWATEC is doing much past work load considerations when factoring in heart rate because it seems prevailing science has little data on nitrogen loading or oxygen toxicity as a factor of heart rate (none I've found yet but would love if someone would be kind enough to post it). As a physiologist, I bought the Galileo in part because of heart rate tracking. There is certainly future knowledge worth gleaning from collecting randomized data from the diving community on heart rate, perceived exertion, and nitrogen loading/oxygen toxicity. I would like to know what research indicates to where blood is shunted during diving brachycardia (is this a typical parasympathetic response?).

I would also be interested in learning about nitrogen/oxygen on athletic divers vs. non-athletic divers. One could assume that those with higher VO2 would certainly have reduced nitrogen loading but is this more compartmental with athletes?

There is a correlation between having a high VO2 max and having a higher level of perfusion--which allows better offgassing. George Irvine proved this repeatedly on dives which average=low Vo2 max divers would have been doing 30 hours decos after big penetrations at Wakulla, while George would do 12 hours....there was more to it than just this though...George wanted bubbling to occur at the shallow stops, where his lungs would be highly effective at eliminating the bubbles. His extremely high Vo2 max allowed greatly reduced stop times deep, and then may have helped the bubbling become as effective as it was in the shallow stops...
After a normal 280 foot tech dive in ocean for 12 minute bottom time, with his accelerated deco, George would wait an hour, and be ready to dive anything all over again. I would do this type of profile with him, but left the profile structuring to him.
This was one of the reasons George was always so big on divers needing to do major cardio training.

 

[bobhog]

Hi Dan

I appreciate what you are trying to say but there are some holes I need to fill in. Any time you have a “correlation” whether or not a cause-and-effect situation exists is not established. The word “proved” itself is misleading. One person’s experience does not tend to indicate scientific discovery. We do not know all the factors that went into the dive you described nor do we have an understanding of groups and their various aerobic capacities. George’s experience may perhaps be in large part due to his accommodation for deep diving rather than his aerobic capacity.

Research from the French navy as well as a study published in the Journal of Physiology (Aerobic endurance training reduces bubble formation and increases survival in rats exposed to hyperbaric pressure) both indicated that aerobic capacity (i.e. VO2max) was not directly related to bubble formation. What seems to follow in research is that the risk of DCI or death related to DCI may have been attenuated by aerobic capacity. Intriguingly the latter study indicated that regardless of aerobic capacity, one could perform a high workload exercise bout immediately prior to diving and realize nearly the same reduction in DCI risk as those with higher VO2max values.

Although I have not read supporting evidence, I would think that reduced DCI in divers with higher aerobic capacity is due in part to two factors:

1) Higher blood volume: increases gas clearance
2) Lower respiration for given workload: decreases N2 exposure

I think it would be inadvisable to disregard industry-established safety practices with regards to decompression simply based upon the anticipation or belief of less N2 loading and certainly not for the assumption that a diver with higher relative aerobic capacity could clear N2 quicker. The latter because, workloads being equal, the diver with the higher aerobic capacity will respire a smaller volume of air (this diver is more energy efficient and does not require as much O2 and therefore will expire less absorbed N2). If you assume that this diver performed the same workload as the lower aerobic capacity diver, then the higher VO2max diver would have absorbed less N2. Obeying established dive safety would tend to give this dive greater protection from DCS.

What I am curious about is this: assuming again equal workloads, the diver with the higher VO2max will have both a higher blood volume and, most notably, greater vascularization to many compartments, especially muscular compartments. What will be the differences with N2 absorption and excretion between the higher VO2max diver and his less trained counterpart? Henry’s Law tells us that liquids may absorb gas at differing rates. It can be safe to assume that all compartments within the body where N2 absorption occurs will have differing N2 absorption rates (their chemical nature will differ therefore their absorption rates will differ).

That leaves us back to square one: heart rate monitoring with the Galileo may have little to do with safe diving calculations and instead function more as a high coefficient of determination with breathing rate. What will have to be figured is the future applicable use of heart rate and diving, in which I am very interested.

 

[DanLVolker]

Hi Dan

I appreciate what you are trying to say but there are some holes I need to fill in. Any time you have a “correlation” whether or not a cause-and-effect situation exists is not established. The word “proved” itself is misleading. One person’s experience does not tend to indicate scientific discovery. We do not know all the factors that went into the dive you described nor do we have an understanding of groups and their various aerobic capacities. George’s experience may perhaps be in large part due to his accommodation for deep diving rather than his aerobic capacity.

Research from the French navy as well as a study published in the Journal of Physiology (Aerobic endurance training reduces bubble formation and increases survival in rats exposed to hyperbaric pressure) both indicated that aerobic capacity (i.e. VO2max) was not directly related to bubble formation. What seems to follow in research is that the risk of DCI or death related to DCI may have been attenuated by aerobic capacity. Intriguingly the latter study indicated that regardless of aerobic capacity, one could perform a high workload exercise bout immediately prior to diving and realize nearly the same reduction in DCI risk as those with higher VO2max values.

Although I have not read supporting evidence, I would think that reduced DCI in divers with higher aerobic capacity is due in part to two factors:

1) Higher blood volume: increases gas clearance
2) Lower respiration for given workload: decreases N2 exposure

I think it would be inadvisable to disregard industry-established safety practices with regards to decompression simply based upon the anticipation or belief of less N2 loading and certainly not for the assumption that a diver with higher relative aerobic capacity could clear N2 quicker. The latter because, workloads being equal, the diver with the higher aerobic capacity will respire a smaller volume of air (this diver is more energy efficient and does not require as much O2 and therefore will expire less absorbed N2). If you assume that this diver performed the same workload as the lower aerobic capacity diver, then the higher VO2max diver would have absorbed less N2. Obeying established dive safety would tend to give this dive greater protection from DCS.

What I am curious about is this: assuming again equal workloads, the diver with the higher VO2max will have both a higher blood volume and, most notably, greater vascularization to many compartments, especially muscular compartments. What will be the differences with N2 absorption and excretion between the higher VO2max diver and his less trained counterpart? Henry’s Law tells us that liquids may absorb gas at differing rates. It can be safe to assume that all compartments within the body where N2 absorption occurs will have differing N2 absorption rates (their chemical nature will differ therefore their absorption rates will differ).

That leaves us back to square one: heart rate monitoring with the Galileo may have little to do with safe diving calculations and instead function more as a high coefficient of determination with breathing rate. What will have to be figured is the future applicable use of heart rate and diving, in which I am very interested.

Hi Bob,
Let me try to help with a few of these holes
George's experiences as a member of the 100 plus WKPP dive team have been widely duplicated with other team members--however, as George has both much higher VO2 max and also much more peripheral adaptation to training ( much more cardio and weight training than most other members) , the others showed "relatively similar" response to this application of decompression techniques.

Back in the mid and late 90's when I was doing a lot of ocean tech dives with George, I was bike racing at an elite level, and has a huge VO2 max as well. I would do whatever profile George did, never anything related to "normal Navy tables", and I would always feel "clean" and ready for anything. This included multiple 280 foot dives in the same day, or a deco dive, followed by flying a few hours later. The story on this, is that the navy tables were based on a population of people with the naturally occuring percentage of PFO's found within it, along with many in the population with poor VO2 max, and low adaptation to training ( which is the perfusion issue).

So the Navy tables would be expected to have so much fudge factor in it, in an attempt to make every one safe, that it actually endangers a high VO2 and fit tech diver, by vastly increasing their exposure at depth. The US Navy apparently felt this way as well, as Spec Warfare people were at a large number of the major dives the WKPP did, led by George and JJ. For them , being able to cut deco from a big dive to 1/3, with less incidence of DCS than traditional practices would cause--was the Holy Grail

I think there is one other series of factors, which makes the deco for George work--this being the unique "shape" of his ascent and deco....There are huge differences between the way we would do this, and the traditional manner. One major difference, is the idea that the blood "should be" getting bubbles forming in them at the shallower deco stops, and the horizontal orientation of the body would make the bubble filtering capability of each person function at maximum...On this issue, I would expect most divers ever included in standard Navy table performed vertical body position ascending---and due to hydrostatic lung loading issues, had a small fraction of their lungs involved in bubble filtering. Additionally, that general population of divers had less ability to move a large volume of blood through there body and to the lung filter, when compraed to an aerobic athlete....George's method of deco definitely asumes you want bubbling for optimal deco, and then you are set to filter this effectively.

Here is alink to a series of articles George wrote---follow what he says on shaping the deco...remember, George is a character, and part of his desire to move DIR ideas across the world, with zero ad budget, was to utilize the WWF wrestling persona, to help carry this message--and it was phenomenally successful

http://www.frogkick.nl/files/george_irvine_dir_articles.pdf
Regards,
Dan Volker

 

[bobhog]

Um, I didn't read anything backed up with hard data here. Kind of a spurious claim to imply that diving tables are inaccurate. I have a problem understanding how a dive table could be "dangerous" for someone with a high VO2 (how high and why is it dangerous).

This fellow seems very experienced but it also seems he has accomodated dives to suit himself. I found nothing compelling in his text to convince me that "fit" divers are less suceptible to DCI. I did not find anything to support his decompression modeling. Without scientific experimentation to justify a certain procedure for eliminating N2 across pressure gradients, then it would not be crazy to say that this would be akin to Russian Roulette. Sooner or later, something's going to catch up with you.

Be safe, do what you know, not what you believe

 

[DanLVolker]

Um, I didn't read anything backed up with hard data here. Kind of a spurious claim to imply that diving tables are inaccurate. I have a problem understanding how a dive table could be "dangerous" for someone with a high VO2 (how high and why is it dangerous).

This fellow seems very experienced but it also seems he has accomodated dives to suit himself. I found nothing compelling in his text to convince me that "fit" divers are less suceptible to DCI. I did not find anything to support his decompression modeling. Without scientific experimentation to justify a certain procedure for eliminating N2 across pressure gradients, then it would not be crazy to say that this would be akin to Russian Roulette. Sooner or later, something's going to catch up with you.

Be safe, do what you know, not what you believe

Sorry, I should have elaborated further...George and JJ, while doing their WKPP penetrations, worked on perfecting tables for a population of highly fit people. They had Dr Bill Hamilton working with them, and their ideas have made it well into the US Navy....The biggest holes in what you are hearing , are my fault, as I am trying to summarize in a few paragraphs, what would take an entire book to cover.

WKPP has over a 100 man team, that has used these tables for tens of thousands of man hours of very extreme profiles ( imagine 6 hours at 280 feet on a 3.5 mile penetration into Wakulla, then a 12 to 16 hour decos)....
This is a population with zero PFO's, and each runs the deco structure explained in George's deco article.
These 2 factors, along with the high perfusion from aerobic and weight training, may not translate well to the general population of divers, except for the actual concepts of the deco shape, and the horizontal body posture on an ascent ( versus the vertical posture you see so frequently--underscored by the practice of going up hand over hand on a rope, vertical the whole time--this is the opposite of what needs to happen for good filtering of bubbles).
I think these issues have huge implications, and is something you could test easily by dopplering yourself and a few others....

As to the dangerous aspect of standard tables to a highly fit diver----If you do a 280 foot deep ocean dive, off of Palm beach or Jupiter Fl, you have to be aware of the possibilities for conditions to change during the dive or the deco--weather, currents, injury in a buddy--many possible factors....this is one reason a long deco is frequently less desirable than a short deco, and on another level, my understanding is that staying much too long on all the deeper stops, will incur so much extra deco time that you will end up doing deco for your deco...this is bad....George is very clear about doing the correct amount of time on ascent speed and on the deep stops, and NOT going above this.
We have been out with divers that did 3 times our deco on deep wreck dives off of Pompano, and this was such a liability for the whole dive planning and execution, that we would never allow them to dive with us again.

Regards,
Dan

 

[boomx5]

Um, I didn't read anything backed up with hard data here. Kind of a spurious claim to imply that diving tables are inaccurate. I have a problem understanding how a dive table could be "dangerous" for someone with a high VO2 (how high and why is it dangerous).

This fellow seems very experienced but it also seems he has accomodated dives to suit himself. I found nothing compelling in his text to convince me that "fit" divers are less suceptible to DCI. I did not find anything to support his decompression modeling. Without scientific experimentation to justify a certain procedure for eliminating N2 across pressure gradients, then it would not be crazy to say that this would be akin to Russian Roulette. Sooner or later, something's going to catch up with you.

Be safe, do what you know, not what you believe

Many of us have been proving the success and efficiancy of the work the WKPP has done in the area of decompression theory for years in the dives we do. Please understand as someone new to the sport there are pieces of the puzzle and lots of history you are not seeing. I know Dan can speak more accurately than I on this matter as he was one of the ones who helped pioneer and test this stuff in the beginning. Also, remember that not all that glitters is gold when it comes to scientific experimentation with decompression modeling. This stuff does not always translate across from the laboratory to the real world environment very well.

 

[boomx5]

Lol...Dan posted before I could post my responce.