falameezer's blog: "Important information"

Water intoxication—not a runner's high - Brief Article
Running & FitNews,  August, 2000  


If you run for a very long time--racing or 
training--water may not be your best choice for 
avoiding dehydration, especially in hot weather. 
Drinking water without electrolytes can lead to 
dilution of normal blood sodium concentration. 
Without the proper amount of sodium, as the blood 
system absorbs extra water, excess fluid can build 
up in the brain and lungs. The condition is 
hyponatremia and the consequences can be fatal 
(see Running & FitNews, September, 1999). Known 
fondly as "water intoxication," runners can 
develop brain swelling and serious amounts of 
fluid accumulation in the lungs. When this 
happens, oxygen is not transported into the 
bloodstream efficiently, and you can become short 
of breath, nauseated, and disoriented. The problem 
is more common in female runners.


Researchers from Baylor College of Medicine in 
Houston studied the development and treatment of 
marathon and ultradistance runners with pulmonary 
edema (essentially dry land drowning as the lungs 
fill with fluid). Seven fit and previously healthy 
marathoners, ranging in age from 29 to 46, became 
ill with respiratory distress, coughing pink 
frothy sputum, low oxygen levels, low serum 
sodium, and brain swelling. Five were female. The 
runners received treatment with intravenous fluids 
containing large amounts of sodium. One woman 
died. Four additional female runners who competed 
in the Houston Marathon this year also had the 
syndrome.


Running shorter distances (an hour or less) does 
not pose the same risks and water is fine for 
rehydration. But ultradistance and marathon 
running in which exertion exceeds four hours can 
set the stage for hyponatremia. Sweating causes a 
loss of water and sodium, which reduces the total 
blood volume. When you drink water it further 
dilutes the blood. As you begin to feel sick, your 
natural response may be to drink more water, which 
can cause your sodium level to become extremely 
low.


As hyponatremia develops, the symptoms are easy to 
confuse with other conditions like heart attack or 
ironically, dehydration or heat stroke. The 
cruelest irony of all is that the response to 
these conditions may be to give more water. Making 
this misdiagnosis, and giving low sodium fluids, 
can be a fatal mistake. The lesson for each 
runner--if you are running an hour or more, 
replace fluids with a sports drink that includes 
electrolytes. If your exertion lasts longer than 
four hours, you need to increase your intake of 
salt beyond that found in most sport drinks. 
Although your body needs water in order to avoid 
dehydration, if your exertion is prolonged, water 
must be balanced with sodium. (Annals of Internal 
Medicine, 2000, Vol. 132, No. 9, pp. 711-714)


* Don't drink more water than you sweat--compulsive water drinkers can start a race with a low sodium level.

* When sweating a lot, choose sport drinks (that contain some sodium) over water (which has none).

* Don't overhydrate in the days before the race. You can't stock up on fluids like a camel.

* Eat a relatively salty diet in the days before the race.

* Eat some pretzels in the last half of the race.

("Running FitNews" Editorial Board Member, Randy Eichner, M.D., Oklahoma City, OK)

COPYRIGHT 2000 American Running & Fitness Association
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