[Paleopsych] NYT: Study Cautions Runners to Limit Their Water Intake
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Thu Apr 14 18:45:45 UTC 2005
Study Cautions Runners to Limit Their Water Intake
April 14, 2005
[An editorial follows.]
By GINA KOLATA
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
"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
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
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.
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
"Instead of waiting until they collapse and then testing their sodium,
maybe we can nip it in the bud," Dr. Siegel said.
Editorial: Brain-Dead From Sports Drinks
April 14, 2005
Brain-Dead From Sports Drinks
For years now, we've been hearing about the importance of hydration
to avoid heat stroke during prolonged exercise in hot weather. Now, it
turns out, too much hydration can kill you.
A study published today in The New England Journal of Medicine should
give weekend warriors reason to rethink the wisdom of quaffing vast
amounts of water or sports drinks while exercising vigorously - at
least if they are engaging in such endurance tests as a marathon. The
study found that a marathon runner could dangerously dilute the blood
with an overdose of liquids, risking a coma and even death. The
problem has also been detected during long military maneuvers,
extended bike rides and blistering hikes through the desert.
An article by Gina Kolata in The Times today describes the slow and
belated recognition of the problem. A South African expert who has
been warning of the dangers for more than two decades told Ms. Kolata
that he had not found a single case when an athlete had died from
dehydration in a competitive race, but that some people had sickened
and died from drinking too much. Typically, an overdose of water
dilutes their blood and reduces the concentration of sodium. Water
enters the cells, causing them to swell, and engorged brain cells
press into the skull; such pressure can lead to confusion, seizures
and a loss of vital functions.
All too often, friends, coaches or emergency personnel assume that the
problem is dehydration and administer yet more liquid, making the
problem worse. The best treatment is a small volume of a concentrated
salt solution, given intravenously, to increase blood sodium
concentrations. Sports drinks containing electrolytes may not help
much as they are mostly liquid themselves.
In the 2002 Boston Marathon, for example, a 28-year-old woman found
herself exhausted after running for five hours and gulping sports
drinks along the way. Wrongly assuming that she was dehydrated, she
chugged down 16 more ounces of a sports drink. She promptly collapsed
and was later declared brain-dead. The concentration of salt in her
blood was found to be lethally low.
In the study published today, researchers at various
Harvard-affiliated institutions tested 488 of the nearly 15,000
runners who completed the 2002 Boston Marathon. They found that 13
percent had blood with abnormally low sodium levels, and that three
runners were in danger of dying. It was not the elite runners who were
at risk - it was those who had taken four hours or more to finish the
race, allowing plenty of time to imbibe excess fluid.
Sports authorities have already issued warnings and tips to avoid
excessive drinking, and rescue workers in the Grand Canyon now carry
devices to test collapsed hikers for low blood sodium. But the
solution is for overly eager endurance runners and hikers to forget
the old mantra that they should drink-drink-drink. Too much liquid can
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