[Bryn-gwlad] Weather Update

[tmcd@panix.com]

On Tue, 2 May 2006, Ld. Alfred <wararcher at yahoo.com> wrote:
>  So, bring plenty of water, your favorite sports drink (no sodas,
> they just dry you out),

The version I heard was "caffeine dries you out", not sodas in
general.  After some poking around in Usenet newsgroups et cetera,
I stumbled on
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmdRetrieve&dbPubMed&list_uids%11>
to search "PubMed" for
    caffeine dehydration
There's a lot of studies saying that caffeine does not cause
dehydration in practice, and none I saw that say it does.
(Quotations at the end.)

For the people out there bashing or poking at other people, I'm
hesitant to make suggestions, because every person is different, and
because of the risks of hyperthermia, dehydration, and electrolyte
imbalance.  I think I've heard that Gatorade diluted by its own volume
of water is common in Ansteorra.

But for spectators at events: as Lord Alfred suggested, you should
bring something (less work for waterbearers), and humans are best
adapted to water.  But it looks like the important thing is to drink
something (probably without alcohol).  If you're facing a choice of
caffeinated drink versus nothing (or less of something else),
I believe you should guzzle that Coke.

Danihel (Lindocollinum)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Various abstracts of abstracts from PubMed:

- only three hits on "ethanol dehydration exercise".  Two abstracts
  showed negative effects of ethanol on recovery from exercise.

- "Int J Sport Nutr Exerc Metab. 2002 Jun;12(2):189-206.

  Caffeine, body fluid-electrolyte balance, and exercise performance.

  Armstrong LE.

  Departments of Kinesiology, Nutritional Sciences, and Physiology &
  Neurobiology, University of Connecticut, Storrs, CT 06269-1110, USA.

  Recreational enthusiasts and athletes often are advised to abstain
  from consuming caffeinated beverages (CB). The dual purposes of this
  review are to (a) critique controlled investigations regarding the
  effects of caffeine on dehydration and exercise performance, and (b)
  ascertain whether abstaining from CB is scientifically and
  physiologically justifiable. The literature indicates that caffeine
  consumption stimulates a mild diuresis similar to water, but there
  is no evidence of a fluid-electrolyte imbalance that is detrimental
  to exercise performance or health. Investigations comparing caffeine
  (100-680 mg) to water or placebo seldom found a statistical
  difference in urine volume. In the 10 studies reviewed, consumption
  of a CB resulted in 0-84% retention of the initial volume ingested,
  whereas consumption of water resulted in 0-81% retention. Further,
  tolerance to caffeine reduces the likelihood that a detrimental
  fluid-electrolyte imbalance will occur. The scientific literature
  suggests that athletes and recreational enthusiasts will not incur
  detrimental fluid-electrolyte imbalances if they consume CB in
  moderation and eat a typical U.S. diet. Sedentary members of the
  general public should be a less risk than athletes because their
  fluid losses via sweating are smaller."

- "These findings question the widely accepted notion that caffeine
  consumption acts chronically as a diuretic."

- "We conclude that sports drinks used during an 18-km run in cool
  environmental conditions do not support the performance better than
  mineral water. The use of sports drinks during an 18-km run leads to
  a higher incidence of both upper and lower GI complaints compared to
  water. Addition of caffeine to the sports drink has no effect on
  either running performance or GI complaints."

- "In summary, there is little evidence to suggest that the use of
  beverages containing caffeine during nonexercise might hinder
  hydration status."

- "Fluid should not be ingested at rates in excess of sweating rate
  and thus body water and weight should not increase during
  exercise. Fatigue can be reduced by adding carbohydrate to the
  fluids consumed so that 30-60 g of rapidly absorbed carbohydrate are
  ingested throughout each hour of an athletic event. Furthermore,
  sodium should be included in fluids consumed during exercise lasting
  longer than 2 h or by individuals during any event that stimulates
  heavy sodium loss (more than 3-4 g of sodium). Athletes do not
  benefit by ingesting glycerol, amino acids or alleged precursors of
  neurotransmitter. Ingestion of other substances during exercise,
  with the possible exception of caffeine, is discouraged. Athletes
  will benefit the most by tailoring their individual needs for water,
  carbohydrate and salt to the specific challenges of their sport,
  especially considering the environment's impact on sweating and heat
  stress."

- "[Caffeine] is relatively safe and has no known negative performance
  effects, nor does it cause significant dehydration or electrolyte
  imbalance during exercise."

- "There is no evidence that caffeine ingestion before exercise leads
  to dehydration, ion imbalance, or any other adverse effects. The
  ingestion of caffeine as coffee appears to be ineffective compared
  to doping with pure caffeine."

I stopped there, except that I *had* to read the abstract of "The
first-of-Ramadan headache."

-- 
Tim McDaniel; Reply-To: tmcd at panix.com