Hyponatremia: What it Is and How to Prevent it
All you marathoners and triathletes out there: have you ever heard of the term hyponatremia? If you haven’t then you should familiarize yourself with this potentially life-threatening condition. A little education can go a long way.
While statistics on this are hard to come by, there have been a few much-publicized cases of this condition that have resulted in the very unfortunate death of the athletes. Deaths from hyponatremia occurred at the 1998 Chicago marathon, the 2002 Boston and Marine Corps marathons and also at the 2007 London marathon. Testing done on athletes following the 2002 Boston Marathon of approximately 500 athletes showed that thirteen percent of those tested had hyponatremia, a fairly alarming figure.
What is Hyponatremia?
So what exactly is Hyponatremia? Hyponatremia is a metabolic condition in which there is not enough sodium (salt) in the body fluids outside the cells. When the amount of sodium in fluids outside cells drops, water will move into the cells in an attempt to balance the sodium levels. This in turn causes the cells to swell with too much water.
Although most cells can handle the swelling, brain cells cannot because they are confined by the skull. It is this brain swelling that causes most of the symptoms of Hyponatremia.
The accepted scientific definition of Hyponatremia is when there is less than 135 millimoles (unit of measurement used to express the amount of a chemical substance) of sodium per liter of plasma. Normal values range from 138 to 142 millimoles and symptoms usually begin when values fall below 130. If the plasma sodium level falls below 120, there will be massive brain swelling and the condition can be fatal.
Long distance athletes, marathoners, and triathletes are the athletes who are most at risk because the longer they exercise the more they sweat, and the more likely they are to drink too much water without taking in enough sodium. Most athletes don’t get into trouble with a short workout. It is longer races, such as the marathon or an Ironman Triathlon where people get into trouble simply because of the extended time that they are out there. Being on the course longer requires the intake of important nutrients to replace what has been expended through sweating. Being told to drink water at every water stop, while sounding like good advice, may lead athletes to this condition.
There are two basic causes of Hyponatremia, consuming too much fluid over too short a time span, and excessive sodium loss through bodily sweat. If both factors are present, the risk is increased. If you are one who sweats at a high rate then your risk is also higher; however excessive fluid intake for a normal sweat rate can also lead to inadequate sodium levels and therefore Hyponatremia as well. If a person is over drinking, meaning that they are not using the amount of water they are consuming for their level of exertion, they will dilute their plasma-sodium concentration and be more prone to the condition.
Early indications that you may be Hyponatremic include disorientation, feeling bloated, nausea and vomiting. High blood pressure and headache often come next. In the more severe cases respiratory distress and seizures can occur and the most advanced stages include coma and possible death. Another very specific indicator of Hyponatremia is weight gain during a race or long run. Most of us don’t stop to weigh ourselves during a run but studies have found that weight gain during a run due to excessive drinking and water retention is the strongest indicator of Hyponatremia.
How do you prevent Hyponatremia? For starters you need to become more aware of your fluid intake and your rate of perspiration. During training runs start to notice how your body reacts to varying amounts of fluid and salt intake. Consume snacks with salt such as chips or pretzels and use sports drinks that have sodium and potassium in addition to water. On race day or prior to a long run make sure you eat a good breakfast and bring a snack with you to eat thirty to sixty minutes before the race starts.
Keep in mind also that the weather plays an important part in your rate of perspiration. In addition to making sure that you are not over doing your fluid intake you need to also stay alert to dehydration if you don’t drink enough. The fear with the competitive mind is that we sometimes overdue everything, so this is certainly a case where you need to maintain a proper balance. It is also a good idea to make sure your supporters and family are aware of this condition as it may be impossible for you to communicate this to them should you have a problem. For most of you this may have never been nor ever will be a problem. However, if you have been running for a number of years you may be able to recall a run or two, or perhaps even a race where you had some of these symptoms.
I have been running for thirty years now and I can think of a few particular cases where I certainly may have had this condition. It’s a little scary now to think that my reaction to these symptoms back then may have been to simply drink more water because that’s what we did to avoid dehydration. Back in the 1970’s and 1980’s, who knew that you could literally drown yourself from drinking too much water while running?
So, the lesson to be learned here is that too much of a good thing can certainly be bad for you. During long runs or races you should drink to minimize your weight loss, but don’t over drink. Add in sports drinks that contain sodium and potassium. In the days leading up to a race or long run snack on salty foods? During your training develop a feel for how your body reacts to what you are putting into it. Just a little precaution can go a long way toward avoiding this potentially serious condition.
© 2012 Bill De Giulio