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beater
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More Chasmism
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We see a lot of this in the summer time. The key is that symptoms tend to correlate more with the rate of depletion of sodium than with the absolute value to which the sodium level falls. In other words, a person may have a profoundly low sodium level that developed gradually and have no symptoms, whereas another person may have a barely low sodium level that developed more rapidly and be markedly symptomatic.

The worst threat is people who exercise in hot weather for a long duration and do not maintain adeqaute salt intake. Such people often start to feel like they are dehydrated when the symptoms begin, and as such they continue drinking more water and making the problem worse.

Supposedly the key is intake of salty snacks (as carbohydtates seem to improve sodium absorption), not the exclusive use of sports drinks.

hfly
 

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Te mortuo heres tibi sim?
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hfly said:
We see a lot of this in the summer time. The key is that symptoms tend to correlate more with the rate of depletion of sodium than with the absolute value to which the sodium level falls. In other words, a person may have a profoundly low sodium level that developed gradually and have no symptoms, whereas another person may have a barely low sodium level that developed more rapidly and be markedly symptomatic.

The worst threat is people who exercise in hot weather for a long duration and do not maintain adeqaute salt intake. Such people often start to feel like they are dehydrated when the symptoms begin, and as such they continue drinking more water and making the problem worse.

Supposedly the key is intake of salty snacks (as carbohydtates seem to improve sodium absorption), not the exclusive use of sports drinks. they fix most of ours up in the ED, so my perception is skewed for sure, as we only get the really bad ones in the unit. more hypo and hyperkalemics in the last few years it seems to me as well.

hfly

ayup. for me, lotsa' water before/after riding, coupled with salty foods when when i know i'm going to be sweating like a pig. no problems so far. granted, you see much more of that in your patient pop. than i do.

most of mine have tended to be geritol poppers who've been consistantly low, and finally got low enough to become symptomatic. a few younger folks the last two summers though.
 

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full article text

Study Cautions Runners to Limit Their Water Intake
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 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.
 

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As usual, people overdoing what should be sensible medical advice. Recommendations like this (how much to drink, what to eat, how to prepare) tend to be faddish. My advice, try a bit of everything, experiment in moderation and then listen each time to what your body has to tell you. Everybody is different. Someone should compile a historical summary of training/medical advice through the ages. I'm sure it would be a huge laugh to read. For example, in years past, doctors and trainers used to recommend that endurance athletes (runners, cyclists etc) smoke to help "open up their air passages". D.
 

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Crazy - I wonder what happens in my case? I try to drink 1 gallon a day, throughout the day, but usually don't drink more than a few ounces (if anything) while riding since it never sounds appealing.
 

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Old news. Decades old.

Anyone who has been physically active in hot weather has known about hyponatremia and how to prevent it. I learned about it in the Boy Scouts 35 years ago.

Why is this such a big revelation now?
 

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dave54 said:
Old news. Decades old.

Anyone who has been physically active in hot weather has known about hyponatremia and how to prevent it. I learned about it in the Boy Scouts 35 years ago.

Why is this such a big revelation now?
Probably because some of us were under the impression that a person would have to drink 4 gallons or more create issues, and lacked even a basic understanding of the mechanics of the body's processing of water during physical activity.
 

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Conflicting Info

I would have to see more sources in order to believe this story. The CTS training guys advise to stay hydrated, as losing 1 lb of water weight is a 10% decrease in performance ability. It sounds that, for the theory above to be true, you would have to sweat 0% for all water to stay in your cells, as they are constantly losing water as you sweat. Sports drinks have levels of salt in order to replace that which you lose. They KEY TERM here is LOSE. I take a 3 liter camelbak with me on 3 hour rides and drink every last bit of it. They say to take 2-3 mouthfulls of hydration every 15-20 minutes of heavy activity. I can tell I lose salt when I sweat due to the white residue left over in the shoulder straps of my Camelbak after the sweat dries. I usually put 50% Gatorade in the bladder so that I replace that. I hear more bad cases of dehydration that I do Hyponatremia. Especially low potassium levels that come along with Dehydration.
 

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HPilot said:
I would have to see more sources in order to believe this story. The CTS training guys advise to stay hydrated, as losing 1 lb of water weight is a 10% decrease in performance ability. It sounds that, for the theory above to be true, you would have to sweat 0% for all water to stay in your cells, as they are constantly losing water as you sweat. Sports drinks have levels of salt in order to replace that which you lose. They KEY TERM here is LOSE. I take a 3 liter camelbak with me on 3 hour rides and drink every last bit of it. They say to take 2-3 mouthfulls of hydration every 15-20 minutes of heavy activity. I can tell I lose salt when I sweat due to the white residue left over in the shoulder straps of my Camelbak after the sweat dries. I usually put 50% Gatorade in the bladder so that I replace that. I hear more bad cases of dehydration that I do Hyponatremia. Especially low potassium levels that come along with Dehydration.
Here's some information to look at

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=PubMed&term=athlete hyponatremia

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=PubMed&term=athlete dehydration
 

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Sounds Familiar

I get thirsty I drink, sometimes too much. I've been know to drift into this area, I would get cramps like I was dehydrating but I was actually over hydrated, flushing all the sodium out of me. I stareted taking a sodium supplement called "thermal tabs" on long rides, really seemed to help ALLOT. It seems I can't keep enough salt in my system.
 

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Need more info.

They never say if the problem is just too much water, or that the water dilutes the minerals. If the mineral levels are adequately maintained, maybe a little too much water is not a problem. Maybe even the craving for water would be diminished if enough salt, potassium, magnesium, etc., were taken in with the water. I'm thinking this "extreme" level of exercise may not apply to a lot of us anyway. They talk about the kidneys not excreting water during these times, but on many of my rides my kidneys seem to be doing their thing (not very convenient at times!) just fine.
 

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Duncan! said:
Excellent! I read over the info. It appears that the loss of sodium, with replacement of only water seems to lead to the problem. Gatorade seems to be specifically engineered to replace sodium and electrolytes that you lose. I really sweat, especially during the summer. Last night, I did 14 miles and drank ~1.25 liters over a time period of an hour. I felt a bit of cramping in my calf muscle though. Not sure what led to that. It was only 64 degrees yesterday with very low humidity, so I didn't feel soaked with sweat. Would regular salt intake during the day also supplement your loss?
 

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This happened to me a few years ago...

I was attempting a 24hr race solo. It was a hot day. I made it to 11pm when things just didn't feel right. I went to my tent to try and recover. Things went down hill from there. I barely recall my time in the first-aid tent before passing out. I ended up spending two nights in the Hood River hospital. I think I slept 20 hrs straight -- before my sodium started to come back up. Cerebral edema... Not painful, but I'd be happy to skip it next time.

For those of you who have stated that hyponatremia is common knowledge, the paramedics at the first aid tent had no clue what was going on. Had they known, they would have whisked me off to the ER much sooner then just trying to hydrate me with an IV. I allowed them to use my hospital records and case for presentations to give other health workers a heads up about this.

This is the same year that a Boston Marathon runner passed away from the same thing. This is a very sobering memory for me.

Enjoy the trails...
Tim
 

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This is what I know....

They do not know a lot about the triggers hyponatremia. But, things get out of kilter when the sodium level drops in your bloodstream but remains high in your soft tissues. Your body likes equilibrium, and thus it floods your soft-tissues with fluids -- causing things to swell up some. And this is fine with everything but your brain (trapped inside your skull). Hence cerebral edema -- not a good thing.

I'm sure medical types can give a better description. This is just what I figured out when I looked into it.

BR,
Tim
 

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HPilot said:
Excellent! I read over the info. It appears that the loss of sodium, with replacement of only water seems to lead to the problem. Gatorade seems to be specifically engineered to replace sodium and electrolytes that you lose. I really sweat, especially during the summer. Last night, I did 14 miles and drank ~1.25 liters over a time period of an hour. I felt a bit of cramping in my calf muscle though. Not sure what led to that. It was only 64 degrees yesterday with very low humidity, so I didn't feel soaked with sweat. Would regular salt intake during the day also supplement your loss?
Over the past several months I've been adding a pinch of salt to my cytomax mixes and it seems to have nearly eliminated my cramping issues. To get more salt with out changing the taste of the mix further, I'm going to carry some pretzel bites stuffed with peanut butter with me for Sea Otter XC this year. I was greatly slowed down by extreme muscle cramps in the last 5-7 miles, last year.
 
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