Nitrox and Excercise - How Long to Wait?

[DandyDon]

(That's why I didn't go running in Utila -- the mornings were nice, but not enough time before diving. I prefer to be conservative rather than a test case.)

I just slept late. :sleeping_

 

[HowardE]

Thanks for your answer cameron. That's more definitive...

I had a MOD (NWGratefulDiver) move this thread from Basic Scuba Discussions to Ask Dr. Deco, so we can get his opinions on this topic as well.

So it sounds like if you're on a liveaboard, or a dive resort, like CCV... You pretty much have to give up working our alltogether for that week (or whatever). Which is what I did last time I was at CCV... Just not work out.

I guess on the other hand... I have read that diving for 1 hour burns about 500 Calories, which is what I typically target in a 30 minute aerobic workout, so if you do 5 dives in a day that's about 2500. I guess you'd have to get up pretty early in the morning, to lift at all, and leave at least 2 hours before diving.

 

[CameronMartz]

That link I posted indicated a two hour minimum, and preferably four hours, before diving when you have exercised -- problems with exercise on both ends it appears.

Yes, but that recommendation is again based upon research done on exercise performed at the surface before decompression to altitude- more akin to exercise at depth on a saturation dive before ascending. Since these recommendations were formulated, several researchers have looked at true pre-dive exercise and its effects on resistance to DCS. These studies have been discussed repeatedly in other posts, so I will only summarize to say that they found that pre-dive exercise was either not harmful or, in some cases, even provided increased resistance to DCS when performed as close as 30 minutes before a dive.

As previously stated, more work is needed here, but it has proven difficult to find real-world cases of DCS reported to DAN that were directly attributed to pre-dive exercise. In fact, in the extensive research I did on this topic for my book, I was only able to find two cases of DCS remotely linked to pre-dive exercise, and both were blamed on extreme dehydration rather than bubbles that might have been nucleated before the dive. That said, it is not hard at all to find cases of DCS linked to POST-dive exercise.

Dr. David Doolette, a decompression researcher now at NEDU, gave a presentation on pre-dive exercise at the GUE conference several weeks ago. He summed it up by saying that if what you're doing exercise-wise before a dive is working for you now, then there isn't enough information to suggest you should change it either way (either more or less time between exercise and diving).

Cameron

 

[HowardE]

Cameron - With your obvious expertise in this subject... Is the amount of calories "burnt" on a dive actually approximately 500 per 1 hour dive? I know this is slightly off of my own topic, but it's something else I was curious about.

Thanks.

 

[CameronMartz]

Cameron - With your obvious expertise in this subject... Is the amount of calories "burnt" on a dive actually approximately 500 per 1 hour dive? I know this is slightly off of my own topic, but it's something else I was curious about.

Thanks.

I have zero faith in these types of figures, whether it is for diving, running, knitting, or whatever. There are way too many variables to calculate a reasonable average value for any activity. Worse is when "experts" have you calculate your personal daily caloric usage from these estimates to match that against your caloric intake.

Hogwash.

In general, look at diving as something to do with your fitness rather than as something to do to increase it, though I'm sure that's not what you were getting at.

Cameron

 

[HowardE]

I think I'm more looking for a way to justify eating cake every night at when I stay at CoCo View.

 

[Dr Deco]

Hello readers:

The interval to post-dive exercise is probably about four hours if the exercise is vigorous, e.g. running. The work on this topic is divided into two general levels of post-dive activity. One is mild exercise for the purpose of increasing blood flow to the tissues thereby eliminating dissolved nitrogen.

One laboratory test has indicated that mild activity is good for reducing Doppler-detectable gas bubbles.

Mild activity is the basis for part of the NASA program to reduce DCS in astronauts during EVA. It has worked well for us.

Dr Deco :doctor:



References :book3:

Dujic Z, Palada I, Obad A, et al. Exercise during a 3-min decompression stop reduces postdive venous gas bubbles. Med Sci Sports Exerc. 2005 Aug;37(8):1319-23.

Jankowski LW, Tikuisis P, Nishi RY. Exercise effects during diving and decompression on postdive venous gas emboli. Aviat Space Environ Med. 2004 Jun;75(6):489-95.

Webb JT, Pilmanis AA, Fischer MD, Kannan N. Enhancement of preoxygenation for decompression sickness protection: effect of exercise duration. Aviat Space Environ Med. 2002 Dec;73(12):1161-6.

 

[HowardE]

Dr Deco - Thanks for that --

Also... Does it matter if you're diving with nitrox mixes from 32-36% for the 4 hour window, or is it all pretty much the same?

In the nitrox course, as I recall, they said to avoid excercise, so that is why I asked in the first place.

Thanks!!

 

[Dr Deco]

In general, I would say the wait is about the same. Certainly it is true that the nitrogen dose is lowered with Nitrox, but it becomes a matter of splitting hairs.

 

[HowardE]

Thanks Dr Deco.

I appreciate it.