Ideal heart-rate control

[HydroApprentice]

I had now some time to play around with this thingy,and I've to say I'm impressed. It's really scary to see first-hand how hyperventilation can mess with the urge to breathe. You watch your saturation drop without no perceived effect whatsoever. I'd call this a valuable lesson! But back to the topic of heart rate. It's as well very cool to see how your heart rate can drop with your first contractions. No conscious technique of breathing or relaxation had such a profound effect on lowering the heart rate. OK, I didn't spend too much with this yet but it's really hard to imagine that a conscious process can induce such a significant drop. The progression "urge to breathe -> contractions -> vasoconstriction -> drop in heart rate" seems to be pretty much hardwired, as growingupninja was suggesting, and there's probably very little we can do about it.
However, we can still try to optimize the induction (cold water, FCR), or utilization of this reflex (relaxation,CO2 tolerance)

 

[Triton1715]

hi Triton,

I am by no means an expert and anyone fell free to correct me but in response to your very first comment, the club I dive with in Brighton have an exercise that we do that might be a step in the right direction for what you are trying to achieve. We call it an oxymoron as it is counterintuitive or moronic; basically it is to do a short static at the start of your dive before duck-diving and doing your dive as normal or usually for longer than normal

You do your standard breath up whatever it is; none, 6 in 12 out, mediative breathing. then you put your face in the water relax go limp and do a short static while you wait for your MDR to kick in and drop your heart rate. the length of time will vary on all the usual factors; your state of mind, fitness, hydration, tension, water temp, how comfortable you are, how many dives you have already done etc. you might use you pulse oxymeter during training to get a handle on how long this is for you and learn to feel it with practice.

I have only been able to really notice my own HR once. We did some heavy cardio (sprint lengths) followed quickly by a static, I could hear my pulse in my ears and feel it in my chest and after only about 20-25 seconds of it remaining high I could feel and hear a considerable drop in HR.

My understanding from what i have read on the course I did and on deeper blue is that once the MDR kicks in the body goes into a kind of survival mode; blood shift, vasoconstriction, reduced HR etc. and this means that the body uses the available O2 more efficiently. by doing nothing in the initial period before this has happened you don’t waste O2 meaning that there is more left in your blood for a longer dive.

My girlfriend went for being able to do 15-20m DNY to 15sec static then 25m length oxy-moron the first time see tried them, which was only her second ever freediving lesson.

There might also be a conditioning element to this as well. Some say you should keep your pre dive routine the same so that your body gets used to it and just doing your breath up can have physiological effect on your body. If you included a short static into you routine for every dive you body might learn to get into that state quicker?

hope that helps and on the equipment side of the thread I would suggest you get the most expensive product you can it is usual more accurate and you are less likely to surpass its capabilities and need to buy another more expensive one.

“buy right or buy twice”

unless you are like hydroapprentice and want to hack it, then get the cheapest you can probably two and start probing



diddavetellyou

Hi diddacetellyou!
That is interesting. It sounds actually quite a bit like the theory behind FRC diving (i.e. static at first part of dive to allow MDR to kick in followed by gentle/mild dynamic). If CDavis reads this thread, he can perhaps shed more, and certainly better, light than I could on it.

Given a few moments prep, I can usually always feel my heart rate one way or another and back when I was a kid first starting in martial arts, we used to do meditation for about 5 minutes before and after class to work on feeling our heart rate and attempting to slow it/calm it quickly. I'm not sure if that's where it came from or not, but I've consequently been able to feel or sense my heart rate most of the time (provided I'm still and can take a few moments to collect myself).

There was only one time that I measured my HR and DR in conjunction and that was about 15 years ago in college. I had always been an avid diver and breath hold snorkeler (I use that term to delineate that fact that I had no knowledge at the time of "freediving" in terms of physiology and the science behind it and was basically just doing very short 30-45 second dives with friends). Nonetheless, I was in a college biology class during lab when we were discussing the MDR. Due to my comfort in water, I was selected as the guinea pig to show the class what it was. They hooked me up to an EKG and had me stick my face in a bucket of ice water. If memory serves, about 35 seconds in to the breath hold my HR suddenly cut crisply and precisely in half. It happened all over no more than 2 full beats which was quite interesting to see on the graph that printed out. Now that I know much more about freediving, it makes me want to see that effect again and see when it hits and how effectively it hits. For some reason, I hadn't really thought about it that specifically until you mentioned it above and now you've gotten me very curious. As soon as I'm over this blasted cold I managed to contract, I think I'll have a new experiment to conduct!

"Buy right or buy twice" . . . .that is dead-on! (Again, with the exception of buying something to take it apart). I've just had it with "cheap junk". So wasteful in terms of both dollars and material and I very much enjoying growing into something than growing out of something. My only caveat is the distinction between buying the most expensive vs. buy the best. Kinda goes without saying, but I've known people in the past that have assumed that merely because something costs more, it must be better. . .which is often the case, but certainly not always.

Thanks again for the info!

 

[Triton1715]

I had now some time to play around with this thingy,and I've to say I'm impressed. It's really scary to see first-hand how hyperventilation can mess with the urge to breathe. You watch your saturation drop without no perceived effect whatsoever. I'd call this a valuable lesson! But back to the topic of heart rate. It's as well very cool to see how your heart rate can drop with your first contractions. No conscious technique of breathing or relaxation had such a profound effect on lowering the heart rate. OK, I didn't spend too much with this yet but it's really hard to imagine that a conscious process can induce such a significant drop. The progression "urge to breathe -> contractions -> vasoconstriction -> drop in heart rate" seems to be pretty much hardwired, as growingupninja was suggesting, and there's probably very little we can do about it.
However, we can still try to optimize the induction (cold water, FCR), or utilization of this reflex (relaxation,CO2 tolerance)

Very neat idea! I can't wait to get one and see exactly the effects of various breathing techniques and they're associated sensations! I hadn't even thought about playing with HV. I think that would be very informative and instructive! Mine can't get here fast enough!

 

[diddavetellyou]

"Buy right or buy twice" . . . .that is dead-on! (Again, with the exception of buying something to take it apart). I've just had it with "cheap junk". So wasteful in terms of both dollars and material and I very much enjoying growing into something than growing out of something. My only caveat is the distinction between buying the most expensive vs. buy the best. Kinda goes without saying, but I've known people in the past that have assumed that merely because something costs more, it must be better. . .which is often the case, but certainly not always.

You are right, just because it’s more expensive doesn’t mean that it is better quality, but in this instance I think that it is relatively true. There is either medical grade closed source expensive stuff aimed at hospitals and medical professionals then there is the consumer HR monitors in watches and sports gear still a lot of money and non modifiable and then the ‘hack’ and ‘Maker’ end of the spectrum that are starting to make head way into this kind of thing.


http://hackaday.com/2014/02/12/wearing-a-homemade-ekg-whilst-base-jumping/


http://hackaday.com/2014/02/13/arduino-powered-ecg-informs-users-of-their-death/


http://www.instructables.com/id/ECG-on-your-laptop/


This is the home made stuff that i started looking at a while ago and it would all be ok for test like you described (head in a bucket) but not that helpful out in the sea or lake during a day diving


Something else to look into is where on the body you take your pulse, here is a thread reply from Trux about how vasoconstriction can cause false, skewed or incorrect reading from different parts of the body.

Wikipedia[/ame]:



More about digital signal processing in pulse oximetry can be found here:

ScienceDirect - Computers in Biology and Medicine : Signal processing methods for pulse oximetry*1




There is also a nice explication of oximetry and related topics at Oximetry.org

image credit Oximetry.org

I remember reading as well that most pulse oxymeter don't work below 30 bpm, this is because of how they are designed and in most medical situation if it goes this low there is a major problem but for freedivers this is not an unrealistic possible HR.


I hope that you don't feel I'm being negative because I'm not, i really want an affordable freediving specific HR monitor and data logger that i can dive with but there are huge hurdles to a diy solution


diddavetellyou

__________________


have drybag will travel

 

[diddavetellyou]

whoops that didn't copy properly here is the link to the" accuracy of oxymeters" thread.

trux's coment is 6th or 7th down.

http://forums.deeperblue.com/threads/accuracy-of-oxymeters.58675/#post-639157

 

[Triton1715]

I hope that you don't feel I'm being negative because I'm not,

Heh heh. . . not in the least! Though I certainly appreciate the concern. Forums are chalked full of misunderstandings thanks to the lack of tonality in text. It makes it really hard to have a conversation with alternate opinions when the text can come off as confrontational rather than a pleasant, open exchange of thoughts.

If you decide to hack something or make a DIY project for diving (rather than dry training), I'd love to see pics of it sometime! I wish I had more time for that stuff. I grew up taking everything apart and designing countless inventions and items that I couldn't otherwise afford to buy new. . . so I have a real sweet-spot for any DIY hardware. Unfortunately, I just don't have time for it anymore, but I'd still love to see what you come up with and if/how effective it is for you.

Thanks for the links to Trux's comments! I've read pretty much the entirety of the freediving forums twice over the past 2 years and remembered something about accuracy issues due to vasoconstriction, but couldn't remember where and didn't want to have to go slogging through the search feature again looking for it. Thanks!

 

[growingupninja]

I've used my $70 pulse oxymeter in the swimming pool. Bit of a bother but it's possible, and it was actually very enlightening. I wore it on my fingertip with a plastic bag duct taped over my hand. It would never hold up for real diving though. Many models of oxymeter come with a crude EKG now, so you can see vasoconstriction happening in real time since it's measuring from the fingertip. I only have experience with mine but it picks up my pulse even when vasonconstriction is so strong that I can't manually find a radial pulse in my wrist. To get anything out of a pulse oxymeter you need to do a lot of reading/research and self experimentation, and you need to train with it over a period of time since every day is going to be a little bit different for every diver.