A couple of weeks ago at my marathon training run, Coach brought up the subject of hyponatremia. Hypo-whaaa? I have been running for years and never even heard of this condition. Here I have been preaching water intake and it turns out, there is actually a huge risk to runners who drink too much water (or any liquids) during long runs.
Causes of Hypernatremia
The condition is not directly “caused” by too much water. Rather, when running long distances, blood flow is directed away from the kidneys and into the legs. The hormones that control salt regulation in your body are “fooled,” causing your kidneys to concentrate your urine with salt, increase free water and lower serum (blood) sodium. Drinking too much fluids, even Gatorade, Poweraide and the like do not impede this increase in serum sodium.
Women are at much greater risk of hyponatremia than men for reasons that are as yet unexplained. First-time marathoners and charity participants (who are often first-timers) also tend to be at risk. Inexperienced runners, fearing that they will become dehydrated, tend to drink too much during races and training runs, not understanding the risks.
Recent medical research has shown that anti-inflammatory OTC drugs like Advil, Motrin, Aleve, ibuprofen, naproxen, etc. may be harmful to runners' kidney function if taken within 24 hours of running (Tylenol has been shown to be safe.) These drugs are thought to increase the chances of developing hyponatremia while running distance due to their action of decreasing blood flow to the kidneys. Doctors recommend that before a race, (specifically beginning midnight before you run) you do not use anything but acetaminophen (Tylenol) if needed until 6 hours after you have finished your race, are able to drink without any nausea or vomiting, have urinated once, and feel physically and mentally back to normal. Then, Advil, Motrin, etc are safe.
Symptoms
In hyponatremia, runners may experience a “clouding” of consciousness that presents itself like drunkenness. You may experience nausea and vomiting as well as lightheadedness and dizziness. As the condition worsens, the brain swells as the sodium level gets lower, and the fluid overload increases.
In the most severe cases, you may lapse into unconsciousness, develop epileptic-like seizures and may even stop breathing or suffer cardiac arrest. Fluid overload of the lungs may produce edema that leads to shortness of breath and coughing up blood. Also, you may experience extreme swelling in the hands and forearms, (I’m not making this up!)
Prevention
Recent scientific research has shown that drinking only when you are thirsty is the best prevention. If you’re drinking no more than 1 cup (8oz) every 20 minutes while on the course you will have enough fluids. In fact, the risk of dehydration, even in the heat, is far less than developing hyponatremia. Not drinking at every water station during your race will help prevent hyponatremia.
In a recent article in Runners World, Dr. Lewis Maharam recommends taking the following precautions to prevent hyponatremia:
1) Drink only when thirsty!
2) Include pretzels or a salted bagel in your pre-race meal.
3) Use a sports drink that has some sodium in rather than plain water, which has none.
4) In the days before the race, add salt to your foods (if don't have high blood pressure or your doctor has restricted your salt intake).
5) Eat salted pretzels during the last half of the race.
6) Carry two small salt packets with you , and consume a single packet before the race and again during the last half of the race.
7) After the race, drink a sports drink that has sodium in it and eat some pretzels or a salted bagel.
8) Stop taking anti-inflammatories (Advil, Motrin, etc.) 24 hours before your race and do not start again until 6 hours post-race.
