Experience From - Matt Mahoney , Rich Schick , Karl King , Paul Schmidt , Michele Burr ,

Matt Mahoney

Just to add to Suzi's post. Warning signs of hyponatremia (low sodium): exhaustion and weight loss (as with dehydration), except that your urine is clear and frequent, every 15 minutes. Your hands, feet, and head swell as water shifts to restore proper sodium concentration. The swelling in the head leads to headache, dizzyness, and staggering. Salty foods will taste very good.

After the Knight Trail 50K last week, I walked another 10 miles with my wife who was still competing. It was about 75 F and sunny, not hot by Florida standards, but this time of year my heat training is not like it is in the summer, so I lose more sodium when I sweat. I recognized the early signs of hyponatremia, so at the next aid station I mixed a spoonful of salt in a cup of water and drank it. Over the next 15-30 minutes the symptoms disappeared and I had no more problems for the remaining 1-2 hours of walking.

Rich Schick

I go with Matt's approach. I seldom use electrolyte drinks in training, then I'm in fat city during races from an electrolyte standpoint. In races I only take electrolyte drinks at every other aidstation unless they are unusually far apart.

In the winter if sweat gets in my eyes it burns -- read high electrolyte content. In the spring as things warm up before long I don't even notice the sweat anymore and then I know I'm getting heat acclimated. Salt replacement can be a vicious circle, the more you replace the more you need. Teaching the body to conserve is the way to go.

The best way to prepare is not an easy question, and there are differences of opinion. The below link provides additional links for an in depth look at the problem.


Karl King

Matt and Rich raise some good points.

  1. As you get heat acclimated, your body's hormonal levels shift to help conserve sodium.

    It was easy to see at the Ice Age Trail 50 on a hot day that my friends from Minnesota who had not had a chance to heat acclimate really suffered from sodium losses. They could not keep up with their needs using only a sportsdrink. The folks who had come up from the South and had some heat acclimation suffered far less.

    My needs for electrolytes were much less in August and September than they were in May and June. This Winter I've run a lot of my miles on a treadmill instead of outside. That has me much warmer and sweating a lot more than I normally would at this time of year. It will be interesting to see what my electrolyte needs are when I go back to running outside. Fortunately, whatever they are, it is easy to adjust intake during a run.

  2. You can reduce your sodium needs by eating a low sodium diet. The human body is very adaptable to sodium intake. Indians in Brazil get by on extraordinarily low sodium intake. People in the central part of China take in about 300 times more sodium than the indians on a daily basis. That's a huge variation. If you take in less sodium, your body will conserve it, and you'll need less during an ultra.

    The biggest difficulty in that is the typical U.S. diet has a lot of sodium, so people lose a lot when they run. In theory, we'd do well to take in much less caffeine and much less salt, but it doesn't happen in practice unless one has a lot of discipline and takes care to watch food intake.

Paul Schmidt, Exercise Physiologist, M.S.

Hyponatremia (plasma sodium <135 mmol:L-1) was first shown to be a danger to ultradistance runners and triathletes by Professor Tim Noakes in 1985. Since then several researchers have reported hyponatremia in athletes ranging between 9 and 29%. In a recent study by Speedy, Noakes, Rogers, et al., sodium levels, weight, and Hct were studied in 605 participants in the 1997 New Zealand Ironman ultradistance triatholon. Race day temp. was about 70 degrees.

They found that 115 athletes (finishers and dnf's) needed medical care after the race. Twenty-six of this group or 23% were hyponatremia.

Post-race weight was reduced by 4.1% of the 543 athletes who were measured both pre and post-race. Twenty-seven of this group maintained or gained weight. Eighteen of these 27 (72%) were hyponatremia (<135). Additionally, pre and post-race weights and plasma sodium concentrations were available on 330 finishers (292 men and 38 women). Fifty-eight (of these 330 (17%) were hyponatremia.

They found an inverse relationship between sodium levels and weight loss. Where athletes who maintained or gained weight had lower plasma sodium. They also determined that a larger % of women had lower post-race plasma sodium concentrations than men. Additionally, they reported that 40 of 264 tested finishers, who had not sought medical care, were mildly hyponatremia (130 to 135). While those who experienced symptoms (confusion, nausea, vomiting, etc.) had plasma sodium levels less than 130.

They concluded that athletes who develop severe symptomatic hyponatremia were suffering from fluid overload that was due to expansion of extra cellular space and not from pooling of fluids in the gut. They suggested that hyponatremia may be the result of either over hydration (accompanied by weight gain) or large salt losses in sweat (with weight loss from dehydration).

It seems there is a fine line between drinking too little and becoming dehydrated or drinking too much (without taking in enough salt) and becoming hyponatremia. Most sports drinks contain only 220 mg per serving, which is too little!

Noakes, T.D, N. Goowin, et al. Water intoxication: a possible complication during endurance exercise. Med Sci Sports Exerc. 7:370-375, 1985.

Speedy, Noakes, Rogers et al. Hyponatremia in ultra distance triathletes. Med Sci Sports Exerc, 31-809-815, 1999.

Michele Burr Ph.D.

Hi everyone,
I'm writing this to "the big list", the PA Buzzards, Virginia Happy Trails Running Club, the Montgomery County Road Running Club (in Maryland) and a few others to say THANK YOU SO VERY MUCH for the Get Well Wishes, Cards, Flowers, and overall concern and support. Wow! I have a lot of wonderful friends!

I am writing to so many people for a few reasons - first, I have received many inquires about how I am doing after the Vermont 100 miler. Also, many people heard about what happened (which I'll explain below) but only got parts of the story. So you'll get the story here - as best I know it, from me, Michele Burr - the person who got a severe case of hyponatremia at VT100. The people who do know about my getting hyponatremia have urged me to post something so that people are aware of this very serious problem.

I must admit, I don't remember much because I had a seizure and went into a coma but I have pieced together many things from people who saw me at the end of the race and from talking with my husband, who thank God, was there at the finish line and with me during my 5 day stay at two hospitals in Vermont and then New Hampshire.

This is a condition in which there is a very low concentration of sodium in your blood. It is also seen in conjunction with WEIGHT GAIN (not weight loss) and most often occurs during endurance exercise lasting more than 5 to 7 hours. (From: http://www.halcyon.com/gasman/water.htm) More specifically, hyponatremia develops as sodium and free water are lost and replaced by fluids, such as plain tap water, half-normal saline, or dextrose in water. Basically, this condition occurs when a person takes in too much water and not enough salt. So you are probably wondering...was I taking Suceed! caps? Was I drinking electrolyte fluids? Yes to both of these questions but obviously I was not taking enough of either one of these things and yes, I was also eating potato chips, peanut butter and jelly sandwiches, fig newtons, and potatoes -but again, it wasn't enough salt and I was taking in too much water. My weight was up 5 pounds at the last weigh-in. To give you an understanding of where my sodium level was compared to a normal person....most people have about 140-145 mEq/L - this is some sort of measure of the amount of salt in your blood. I had 113 mEq/L. This is extremely low. So, why is this a problem? Because you need sodium in your blood for your brain to function.

The answer to this question is the scary part and why this is such a medical emergency when it occurs.

Many of the symptoms are NEUROLOGICAL in origin. Level of alertness can range from agitation to a coma state. Variable degrees of cognitive impairment (eg, difficulty with short-term recall; loss of orientation to person, place, or time; frank confusion or depression). Other symptoms include seizure activity and irrational behavior. In patients with acute severe hyponatremia, signs of brainstem herniation, including coma; fixed, unilateral, dilated pupil; decorticate or decerebrate posturing; and respiratory arrest. Coma and seizures usually occur only with acute reduction of the serum sodium concentration to less than 120 mEq/L. (Remember my sodium level was at 113 mEq/L.)

I didn't recognize where I was or who my friends were or who my husband was at the end of the race. I walked the last 5 to 10 miles which is very unusual for me and people said I didn't know who they were and it appeared as though I didn't even know I was in a race. Shortly after I crossed the finish line on Saturday night I started to vomit uncontrollably then I had a seizure then I went into a coma. I remained in a coma for 3 days. At some point before I woke up out of the coma I began the "irrational behavior" mentioned above. I pulled out all my IVs and ripped off my EKG patches and tried to kick and hit the nursing and neurosurgeon staff. I was very combative whenever someone tried to touch me and was eventually given antipsychotic medication. When I woke up I didn't know where I was, what had happened, what month, or year it was. Upon being forced to give a guess for the month I told the neurosurgeons, "I think it's Vermont" for the month. I couldn't read and I couldn't add numbers. On Tuesday after the race I started to feel much, much, better. I could read again and I had watched a car commercial to figure out what year it was. I also got a lot of the story about what happened from my husband. It was on this day (or maybe Monday?) I learned I had been in another hospital earlier. Why was I first in a small local hospital (Ascutney in Windsor, VT) and then transferred by ambulance to Dartmouth-Hitchcock? That has to do with the scariness about how to treat this medical emergency. It you don't do it right, it will lead to further and permanent brain damage.


From http://www.rice.edu/~jenky/heat.html:

It says that the condition is frequently mis-diagnosed as dehydration and that the consumption of water makes matters worse because it dilutes the blood sodium concentration even further than it already is.

From http://www.emedicine.com/EMERG/topic275.htm

"The principal causes of morbidity and death are when chronic hyponatremia reaches levels of 110 mEq/L or less and cerebral pontine myelinolysis (an unusual demyelination syndrome that occurs when HYPONATREMIA IS CORRECTED TOO QUICKLY).

Much has been written about treatment of hyponatremia and the potential adverse outcome of central pontine myelinolysis. This condition is demyelination of the pons, which can lead to mutism, dysphasia, spastic quadriparesis, pseudobulbar palsy, delirium, coma, and even death. Raising the serum sodium concentration more than 25 mEq/L or to a normal or above-normal level in the first 48 hours increases the likelihood of central pontine myelinolysis.

The main controversy in the literature surrounds treatment of chronic symptomatic hyponatremia because, as mentioned, central pontine myelinolysis may result if the condition is corrected too rapidly. Therefore, although treatment in these patients is similar to that just described, the rate of correction should be slower (0.5 to 1 mEq/L per hour). Aggressive therapy should be discontinued when the serum sodium concentration is raised 10% or symptoms abate."

Upon being admitted at the first hospital in Vermont my soium level was 113 mEq/L but then quickly went to 116 and the next reading was at 126. The hospital felt uncomfortable and kept telling my husband it was possible I'd get "PONDS" - which is central pontine myelinolysis (permanent brain damage). They also told him to think about long term care for me and that "things could turn out a number of ways". They also asked him if I remained in a vegetative state, would I want my organs donated and did I have a living will prepared. At this point, an ambulance took me to New Hampshire to Dartmouth-Hitchcock. Needless to say, I think I aged my husband about 10 years during these 5 days.

Well, so far I feel I am about 95% back to where I was neurologically before the race. (Physically, I lost 10 pounds.) I couldn't remember my password when I got to my office so I couldn't log into my computer and I forgot a combination lock number I often used. I also forgot a few people's names. I had a little bit of trouble typing and signing my name but that seems to be gone now. The last clear things I remember from the race are at the mile 18 aid station. I am also a bit spacey (it's a bit difficult for me to concentrate) but I can drive. I am a research scientist so it's important that I be able to generate and interpret statistics. I haven't tried that yet but I'm optimistic.

Here are a few more links (in case you just can't get enough about hyponatremia):


Finally, the way to avoid this in the future (for me) is to drink less water and eat more salt. I will also push for a blood test from my doctor before I run another 100 (this was my 5th one) to make sure I am not starting out at a deficit - which is what the doctors were suggesting at Dartmouth-Hitchcock Hospital. They said that my low sodium diet, combined with a high volume of running (sometimes as much as 100 miles/week) and sweating in the heat and humidity here in the Washington DC area were the problem combined with the low volume of electrolyte fluids (relative to the amount of water I was taking in).

This was scary. I hope some people will be educated by reading this and for the many people who emailed and asked me what happened, I hope this answered their questions.

Thank you so very much again everyone for your concern. My friends, co-workers, relatives, and the ultrarunning community have been great!