Multi-day repetitive dive planning: planning for liveaboard divng

[gj62]

glbirch - check out http://www.scuba-doc.com/exerdcs.html

 

[octotat]

Enough cannot be said about being in condition before a heavy dive trip. Multiple dives, especially deep, for multiple days is certainly not to ever be taken lightly, as dcs is so complex that all variables cannot be taken in by your dive computer. The preparation should start long before the dive trip, not just the evening before sitting around reading dive tables. The better condition you are in, the more vasculature in body tissue, the better the gas transfer. It's the same reason people in great condition don't "suck wind" when exercising. The other benefit is breathing less gas for a given effort during the dive. I know this is offhandedly mentioned in dive training, but I don't feel they put the proper emphasis on it.

BTW, I'm no Jack Lalanne, but I try to fight the good fight in the gym and on the bike, and prior to any significant dive trip, I try to swim as much as possible. I'd rather suffer in the gym/pool so that I can breath easy during my dives!

 

[glbirch]

glbirch - check out http://www.scuba-doc.com/exerdcs.html

Thanks for the link gj62, but it focuses on the link between pre- and post-dive excercise and micronuclei formation. Doesn't really give me the information I'm wondering about.

 

[Diver0001]

Apologies for the hijack, but looking at two opposite recommendations has me curious.



Is this a personal theory, or is there research that backs it? How does my computer know my personal heart-rate? Combining that comment with:



brings a whole set of questions to mind. Does this imply an 'optimal' heart/breath rate for N2 elimination? What (if any) would be variables? Given that individual at-rest heart rates can vary from under 40 beats/minute to over 90 depending on age, fitness and genetics, it sounds a little simplistic to say that both cases are true.

Those are excellent questinos for Dr. Powell. I have this information from him. Feel free to spin off a thread about it in the Dr. Deco forum.

R..

 

[grazie42]

On the live-aboards I´ve been on they´ve recommended 5 minute safetystops rather than the normal 3 and slower ascentrates...
After a few days of diving the ops have stressed the issue of slow ascent rates further just to "make sure" that people don´t push the limits...

On my last live-aboard they even had a chart where they recorded your air in/out, depth and bottom time after every dive. I´m not suggesting that you let others plan your profiles but with a good op they´ll try to help you stay safe and choose dive sites with respect to the divers on-board.

I tend to use nitrox at least once a day on the days of the deeper dives. A good op will usually make this easy by doing a mellow drift/reef dive after a deeper dive. I´ve never done more then 4 dives a day while on live-aboard and I don´t really see how you could do more, and still have meaningful dives...

 

[reubencahn]

On the surface that would be logical, but many of us have poor breathing habits when we are awake. Sleeping, our respiration and heartbeat slow, but we tend to breath deeper (IIRC). So I personally would not assume that sleeping during my surface interval is bad. As well, on a multi-day repetitive-dive trip, the majority of your off-gasing surface interval is at night. I would also suspect that the blood stream flushes N2 fairly quickly and it's the slower tissue compartments that are more of a factor. Would breath rate make much of a difference to how fast those tissues give up N2?

Maybe I should ask to have this moved. I don't want to take over reubencahn's thread.

Don't worry about me. I just wanted to spark conversation about relevant topics.

I'm also skeptical of the idea that sleeping can make a real difference. There's empirical data showing post dive excercise can lead to dcs. Beyond this, it's easy to imagine the mechanisms. When I excercise, my heart rate can climb pretty rapidly from 70 to 140. My systolic pressure can climb 20 to 40 points. In theory I could begin moving a lot more blood and gas and the increase in systolic pressure could open a PFO allowing bubbles that would otherwise be scrubbed to avoid the lungs and get into the arterial side of the circulatory system. On the other hand. When I'm sitting in a chair reading a book, my pulse is 70. When I'm sleeping it's probably 68. I doubt there's any real effect on blood pressure. My respiration may slow substantially, but I probably breathe more deeply. I'd like some empirical data on this.

 

[glbirch]

Don't worry about me. I just wanted to spark conversation about relevant topics.

I'm also skeptical of the idea that sleeping can make a real difference. There's empirical data showing post dive excercise can lead to dcs. Beyond this, it's easy to imagine the mechanisms. When I excercise, my heart rate can climb pretty rapidly from 70 to 140. My systolic pressure can climb 20 to 40 points. In theory I could begin moving a lot more blood and gas and the increase in systolic pressure could open a PFO allowing bubbles that would otherwise be scrubbed to avoid the lungs and get into the arterial side of the circulatory system. On the other hand. When I'm sitting in a chair reading a book, my pulse is 70. When I'm sleeping it's probably 68. I doubt there's any real effect on blood pressure. My respiration may slow substantially, but I probably breathe more deeply. I'd like some empirical data on this.

As suggested, I'm going to repost the question in the Dr Deco forum later today.

Edit: Done. posted at http://www.scubaboard.com/t58380.html

 

[MikeFerrara]

My understanding is that the risk in heavy work isn't due to an increase in cerculation but rather stressing joints causing cavitation and the formation of bubbles in fluids which can grow.

The problem with sleeping is the lack of cerculation in some parts of the body due to a total lack of movement.

It's also my understanding that light excersize that doesn't stress joints generally promotes good offgassing.

As far as I know none of it has to do with pulse rate or breathing rate.