"Kinky Cowboy" <
[email protected]> wrote in message
news:
[email protected]...
> There are two different problems, and it doesn't help to conflate
> them. Anybody exercising hard, especially in a hot and or humid
> environment, will lose a lot of both water and sodium through
> perspiration. Trying to replace only one of these, by drinking only
> plain water, leads to hyponatremia just as surely as not replacing the
> water leads to dehydration.
>
> By drinking a properly balanced solution of electrolytes in water, you
> can avoid both problems.
>
> There's an online hydration calculator, with sport specific inputs, at
> http://www.hydraopt.com
>
> Taking reasonable guesses at the size and weight of this Guevara
> fellow, he probably needed to drink no more than about 3.5 litres for
> the marathon; by taking 3 litres of water and no electrolytes at the
> start, he was setting himself up for trouble.
>
> Kinky Cowboy*
>
> *Batteries not included
> May contain traces of nuts
> Your milage may vary
>
Perhaps, not quite correct. No one is drinking 0.9% saline solution -
similar to sea water or your body's extracellular fluids. The hyponatremia
problems in endurance atheletes come from too much water and not from lack
of salt. Under most conditions, athletes do not lose that much sodium or
other electrolytes for that matter. That is why everyone stopped taking
salt tablets several decades ago. Of course, some electrolyte replacement is
appropriate.
The drink before you are thirsty admonition has been promulgated by many
experts in the past. This recommendation is now being re-evaluated by most
exercise physiologists. Very vigorous hydration does not enhance
performance and may cause serious problems of hyponatremia as noted in this
thread. Here's a link to the official position of the American College of
Sports Medicine:
http://www.acsm-msse.org/pt/pt-core/template-journal/msse/media/0196.htm
For a less technical and more user friendly summary of the recommendations
in video format go to this site:
http://sportsmedicine.about.com/cs/nutrition/a/aa070703a.htm
and click on "Can Too Much Water Sink Runners?"
BobT