hyperhidration

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http://www.nytimes.com/2005/04/14/health/14water.html?pagewanted=all

 

The New York Times

Health

 

Study Cautions Runners to Limit Their Water Intake

By GINA KOLATA

 

Published: April 14, 2005

 

After years of telling athletes to drink as much liquid as possible to avoid

dehydration, some doctors are now saying that drinking too much during

intense exercise poses a far greater health risk.

 

An increasing number of athletes - marathon runners, triathletes and even

hikers in the Grand Canyon - are severely diluting their blood by drinking

too much water or too many sports drinks, with some falling gravely ill and

even dying, the doctors say.

 

New research on runners in the Boston Marathon, published today in The New

England Journal of Medicine, confirms the problem and shows how serious it

is.

 

The research involved 488 runners in the 2002 marathon. The runners gave

blood samples before and after the race. While most were fine, 13 percent of

them - or 62 - drank so much that they had hyponatremia, or abnormally low

blood sodium levels. Three had levels so low that they were in danger of

dying.

 

The runners who developed the problem tended to be slower, taking more than

four hours to finish the course. That gave them plenty of time to drink

copious amounts of liquid. And drink they did, an average of three liters,

or about 13 cups of water or of a sports drink, so much that they actually

gained weight during the race.

 

The risks to athletes from drinking too much liquid have worried doctors and

race directors for several years. As more slow runners entered long races,

doctors began seeing athletes stumbling into medical tents, nauseated,

groggy, barely coherent and with their blood severely diluted. Some died on

the spot.

 

In 2003, U.S.A. Track & Field, the national governing body for track and

field, long-distance running and race walking, changed its guidelines to

warn against the practice.

 

Marathon doctors say the new study offers the first documentation of the

problem.

 

"Before this study, we suspected there was a problem," said Dr. Marvin

Adner, the medical director of the Boston Marathon, which is next Monday.

"But this proves it."

 

Hyponatremia is entirely preventable, Dr. Adner and others said. During

intense exercise the kidneys cannot excrete excess water. As people keep

drinking, the extra water moves into their cells, including brain cells. The

engorged brain cells, with no room to expand, press against the skull and

can compress the brain stem, which controls vital functions like breathing.

The result can be fatal.

 

But the marathon runners were simply following what has long been the

conventional advice given to athletes: Avoid dehydration at all costs.

 

"Drink ahead of your thirst," was the mantra.

 

Doctors and sports drink companies "made dehydration a medical illness that

was to be feared," said Dr. Tim Noakes, a hyponatremia expert at the

University of Cape Town.

 

"Everyone becomes dehydrated when they race," Dr. Noakes said. "But I have

not found one death in an athlete from dehydration in a competitive race in

the whole history of running. Not one. Not even a case of illness."

 

On the other hand, he said, he knows of people who have sickened and died

from drinking too much.

 

Hyponatremia can be treated, Dr. Noakes said. A small volume of a highly

concentrated salt solution is given intravenously and can save a patient's

life by pulling water out of swollen brain cells.

 

But, he said, doctors and emergency workers often assume that the problem is

dehydration and give intravenous fluids, sometimes killing the patient. He

and others advise testing the salt concentration of the athlete's blood

before treatment.

 

For their part, runners can estimate how much they should drink by weighing

themselves before and after long training runs to see how much they lose -

and thus how much water they should replace.

 

But they can also follow what Dr. Paul D. Thompson calls "a rough rule of

thumb."

 

Dr. Thompson, a cardiologist at Hartford Hospital in Connecticut and a

marathon runner, advises runners to drink while they are moving.

 

"If you stop and drink a couple of cups, you are overdoing it," he said.

 

Dr. Adner said athletes also should be careful after a race. "Don't start

chugging down water," he said.

 

Instead, he advised runners to wait until they began to urinate, a sign the

body is no longer retaining water.

 

The paper's lead author, Dr. Christopher S. D. Almond, of Children's

Hospital, said he first heard of hyponatremia in 2001 when a cyclist drank

so much on a ride from New York to Boston that she had a seizure. She

eventually recovered.

 

Dr. Almond and his colleagues decided to investigate how prevalent

hyponatremia really was.

 

Until recently, the condition was all but unheard of because endurance

events like marathons and triathlons were populated almost entirely by fast

athletes who did not have time to drink too much.

 

"Elite athletes are not drinking much, and they never have," Dr. Noakes

said.

 

The lead female marathon runner in the Athens Olympics, running in 97-degree

heat drank just 30 seconds of the entire race.

 

In the 2002 Boston Marathon, said Dr. Arthur Siegel, of the Boston

Marathon's medical team and the chief of internal medicine at Harvard's

McLean Hospital in Belmont, Mass., the hyponatremia problem "hit us like a

cannon shot" in 2002.

 

That year, a 28-year-old woman reached Heartbreak Hill, at Mile 20, after

five hours of running and drinking sports drinks. She struggled to the top.

Feeling terrible and assuming she was dehydrated, she chugged 16 ounces of

the liquid.

 

"She collapsed within minutes," Dr. Siegel said.

 

She was later declared brain dead. Her blood sodium level was dangerously

low, at 113 micromoles per liter of blood. (Hyponatremia starts at sodium

levels below 135 micromoles, when brain swelling can cause confusion and

grogginess. Levels below 120 can be fatal.)

 

No one has died since in the Boston Marathon, but there have been near

misses there, with 7 cases of hyponatremia in 2003 and 11 last year, and

deaths elsewhere, Dr. Siegel said. He added that those were just the cases

among runners who came to medical tents seeking help.

 

In a letter, also in the journal, doctors describe 14 runners in the 2003

London Marathon with hyponatremia who waited more than four hours on average

before going to a hospital. Some were lucid after the race, but none

remembered completing it.

 

That sort of delay worries Dr. Siegel. "The bottom line is, it's a very

prevalent problem out there, and crossing the edge from being dazed and

confused to having a seizure is very tricky and can happen very, very fast,"

he said.

 

Boston Marathon directors want to educate runners not to drink so much, Dr.

Siegel said. They also suggest that runners write their weights on their

bibs at the start of the race. If they feel ill, they could be weighed

again. Anyone who gains weight almost certainly has hyponatremia.

 

"Instead of waiting until they collapse and then testing their sodium, maybe

we can nip it in the bud," Dr. Siegel said>>>

 

Now I understand why my trekking guru always forbade me to drink while

trekking. And why in the Russian army they would force soldiers to take lots

of salt before a long march. And why Indians put salt in their drinks and on

their fruits...

 

ys apd