Hello,

I just wanted to share some findings on my web searches.

The issue is very complex as I can see from articles like

http://www.trainermed.com/z203_MR_intestinal.htm (a panel
debate with citations)
http://www.squash.com.ar/notasmundo_energias.htm
off-line, use cache
http://216.239.53.100/search?q=cache:http://www.squash.com
.ar/notasmundo_energias.htm&sourceid=opera&num=0&ie=utf-8&o
e=utf-8
(Spanish, but can translate via Google)
http://www.intelihealth.com/IH/ihtIH?d=dmtContent&c=36163&p
=
(a good resume in English, Reviewed By Harvard MS

Trying to sum up:

It seems that for normal exercise sessions (like the typical one
hour) there is no risk to lose electrolite balance, so taking plain
water can be enough. Water is lost at a higher pace than
electrolites.

The absorption of water in the intestine is helped by the presence
of glucose and sodium. The amount is hard to determine.
Prolonged exercise could require more carbohydrates, but at
certain point they slow water absorption.

Temperature of water is important: 8 - 13 C.

Hydration is a continuos process: start drinking small amounts
250-500 cc before (20-40 min), during and after exercising.

"Don't judge your hydration level by how much you appear to be
perspiring. In a dry climate, you'll actually sweat up to 10 percent
more than in a humid climate, even though you seem to be
sweating less. (Reason: the sweat evaporates much faster in dry
weather.)"

"In hot weather, wear light-colored, porous clothing that allows
sweat to evaporate freely. Full evaporation requires wet clothing,
so avoid changing into a dry shirt."

Best

Riso

[Many people try hard to keep themselves cool while doing workouts and to not
let their body temperature rise. However, this ignores the fact that such a rise
will be life extending because it causes heat shock proteins to be generated. Of
course, this does not mean that one should overdo it. Just as running to
exhaustion is not healthy, neither is exercising strenuously in hot sunshine.
--Paul]