Pre-dive hydration

[chickdiver]

You mean Heather's probably got a good reason for sucking off that Big Gulp right up until she zips up her dry suit?

I'm like Pooh- except that "Heather's run on unsweet tea." :11:

 

[DandyDon]

I'm like Pooh- except that "Heather's run on unsweet tea." :11:

Which would be a known diuretic...?

Even tho we probly should not take this small study as THE way to hydrate, I'm going to keep doing it like they did, as I have been. Couldn't hurt, may help, seems like it would.

Still like to know the salt and sugar used per liter...?

 

[Gene_Hobbs]

Which would be a known diuretic...?

and the studies showing volume intake being greater than the volume lost given the small amount of caffeine in most beverages probably mean nothing... How about the UK thesis where they 're-hydrated' the subjects with beer? That one made my head spin too.

Still like to know the salt and sugar used per liter...?

The paper is available for sale and linked to from PubMed... or maybe join UHMS and get it from their library held at Duke? Oh never mind, it's too late and I'm too tired for this...

1300mL of fluid with 157 meq.1^-1 Na+ and 23g.1^-1 carbohydrate (Osmolality = 324 mOsml1^-1)

 

[SparticleBrane]

1300mL of fluid with 157 meq.1^-1 Na+ and 23g.1^-1 carbohydrate (Osmolality = 324 mOsml1^-1)

Holy cow, a "real answer" from Gene. Ladies and Gents, this isn't something you see every day...

Now if only I still had my notes from my high school AP Chemistry class handy...

 

[DandyDon]

I always appreciate Gene's posts - just don't understand the last one, but okay....

 

[Gene_Hobbs]

I always appreciate Gene's posts - just don't understand the last one, but okay....

Go to the second page of this pdf:
Moon. Adjuvant therapy for decompression illness. SPUMS 1998 Volume 28 Number 3. RRR ID: 5947

The table at the bottom should help (it is old though, should always check the current numbers from beverages and make sure your 'units' match). Sorry that I am not familiar with French products.

 

[TSandM]

In response to the question as to the value of hydrating acutely versus over time, there are conceptually three fluid spaces in the body: The intravascular space, which is the volume contained within blood vessels; the extracellular space, which is the volume of fluid around and between the cells, and the intracellular space. Water moves freely among the spaces, but diffusion takes time. Gains or losses of volume occur first in the intravascular space, and then equilibrate with the other two spaces. Medical physiology has evidence that losses in the intracellular and interstitial spaces are the ones that correlate with bad outcomes (in other words, the body tolerates temporary losses within limits from the intravascular space).

Acute hydration like the process described in the paper really is only expanding the intravascular space, and that temporarily, as unless you are actually volume depleted before the dive (think hung over ), the kidneys will eventually eliminate the fluids you consumed. This is why I have argued that aggressive hydration immediately before a dive was unlikely to be useful, assuming you are well hydrated to begin with.

This is a small study, and its analysis of the results may be off track, but it is at least intriguing evidence that I may be wrong. Since the only real RISK of hydrating immediately before a dive is having to cut your dive short because of a full bladder, it seems to me that making more of an effort to hydrate acutely might be quite reasonable, as we wait for further investigation.

Just my take on it.

 

[DandyDon]

Go to the second page of this pdf:
Moon. Adjuvant therapy for decompression illness. SPUMS 1998 Volume 28 Number 3. RRR ID: 5947

The table at the bottom should help (it is old though, should always check the current numbers from beverages and make sure your 'units' match). Sorry that I am not familiar with French products.

A very interesting read, albeit not a light one. Many divers here on SB often claim that water is best :silly: and I am temped to ask what comic book that came from. Found this excerpt interesting...

Ingestion of plain water stimulates urine output via
a decrease in plasma osmolality and inhibition of
antidiuretic hormone (ADH) secretion, producing a false
impression of adequate rehydration. Therefore a
solution containing electrolytes, particularly sodium, is
preferable.

Beyond that point is going require study on this cowboy's part, tho; it'd be easy to screw this up.

thanks again!

 

[vetdiver]

I do agree that one must take a single study (especially one with an n=8) too seriously - anyone in science and/or with access to Pub Med knows that you can find at least one paper demonstrating almost any scientific idea. I like to see multiple papers, especially those containing large n's, to really buy into an idea...

That said, there was statistical significance, which is not that easy to accomplish with an n=8!! Our statisticians often recommend an n=10 per group to ensure we are able to demonstrate statistical significance and not just a trend. Also, from a personal note, I occasionally (maybe a total of 4 times) had localized skin mottling on my torso after a dive - and in each case, I was dehydrated prior to the dive...though 3 of the 4 incidents were shore dives with a surf entry, so the exercise getting out of the water could have also played a role.

(Note: I am not overweight and have had a heart scan in the past for other reasons - no PFO or other issues.)

Of course, as a girl who dives in a drysuit, to really test this theory, I'll either have to wear Depends or a She Pee...or do super-short dives.... I think I'll just try to ensure better hydration status before I submerge...

 

[limeyx]

Acute hydration like the process described in the paper really is only expanding the intravascular space, and that temporarily, as unless you are actually volume depleted before the dive (think hung over ), the kidneys will eventually eliminate the fluids you consumed. This is why I have argued that aggressive hydration immediately before a dive was unlikely to be useful, assuming you are well hydrated to begin with.
...
Just my take on it.

Good to know -- I'd never dive hungover.