Interesting exercise before diving study

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Brian Monteith - 11 Mar 2004 16:35 GMT

Below is an email from a medical mailing list.

It often contains some pretty interesting stuff but this latest item
regarding exercise is probably to most useful to the average diver.

You can subscribe or just read the article, follow the link.

Subject: Interesting exercise before diving study!

We thought that you might be interested in this abstract of an article
that is in the Journal of Physiology about the protective effect of
exercise in the 24 hours prior to diving. Researchers at the
University of Split and St. Olaf's Hospital in Norway followed up on
findings in rats with interesting studies on dry divers (chamber
dives) with venous gas emboli and found a significant decrease in
number and size of bubbles in divers after one bout of strenuous
exercise in the 24 hour period prior to diving.

http://jp.physoc.org/cgi/content/abstract/jphysiol.2003.059360v1

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Charlie Hammond - 11 Mar 2004 18:02 GMT

> ... significant decrease in
>number and size of bubbles in divers after one bout of strenuous
>exercise in the 24 hour period prior to diving.
>
>http://jp.physoc.org/cgi/content/abstract/jphysiol.2003.059360v1

Demonstrating once again that even highly "precise" decompression
models are only approximately "accurate".

(If you don't understand this statememt, first look up and understand
the meanings of and difference between "precise" and "accurate".)

Signature

Charlie Hammond -- Hewlett-Packard Company -- Ft Lauderdale FL USA
(hammond@not@peek.ssr.hp.com -- remove "@not" when replying)
All opinions expressed are my own and not necessarily my employer's.

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bullshark - 11 Mar 2004 18:51 GMT

>We thought that you might be interested in this abstract of an article

it's very old news...

>exercise in the 24 hours prior to diving.

...and you've misrepresented it.

The study looks at exercise *20* hours before compression. While your
characterization is true in the strictest sense, you might give
someone the idea that any old exercise, any old time before diving
is beneficial, and that is not only NOT true, it could get someone
bent.

Furthermore it is NOT *strenuous* exercise, it is *aerobic* exercise.

>Researchers at the
>University of Split and St. Olaf's Hospital in Norway followed up on
[quoted text clipped - 4 lines]
>
>pimpme://jp.physoc.org/cgi/content/abstract/jphysiol.2003.059360v1

so take a hike,

bullshark

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Bryan Heit - 11 Mar 2004 18:59 GMT

I would warn people of going just off the abstract. In fact as a
someone who does medical research I am very surprised that this paper
made the Journal of Physiology - there standards are usually much higher
then this. If you can access the whole paper you will see that the
effects of exercise varies greatly between people (table 1):

-in 2/10 (i.e. 20%) of cases exercise induced an increase in bubbles
-in another 2/10 (20%) of cases exercise reduced bubble prevalence
by less than 50%
-among the other 6 divers exercise reduced bubbles by 55%-100%

More importantly, and quite frankly the fatal flaw, is that this study
does not take into account any factors of the volunteers. All
volunteers were male, but the spread in ages was limited (16 years
spread, 22-38), and they ranged from in very good shape (BMI 21.5) to
obese (BMI 29.9). Some of the divers were smokers, some were not. But
none of these factors was taken into account when the authors present
their results, so we do not know if the "exercise induced reduction" was
due to exercise, or due to these other factors.

So if your female, or a male younger than 22, or a male older than 38,
or if you smoke, or if you don't smoke, or if you're in good shape, or
you're in bad shape, of for that matter if you're still breathing, you
can't really judge if exercise will help or hinder your risks of DCS on
the basis of this paper.

Bryan

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