Pass the Salt, Please!
Marathoners Might Need More Sodium In Their Diets

BY CARYN HONIG RD LD
(Footprints)

After the 2000 Compaq Houston Marathon, 21 runners wound up in the medical tent with symptoms including, but not limited to, dizziness, chills, muscle cramps, weakness, and nausea. Although the symptoms were very similar to those of dehydration, the correct diagnosis for these particular runners was hyponatremia. "2000 was the first year that we could test for hyponatremia in the George R. Brown Convention Center," said Dr. Joe Chorley, Sports Medicine Physician at Baylor College of Medicine and Assistant Medical Director for the Compac Houston Marathon. "We don’t have the answers yet as to why some people are more prone than others to hyponatremia, however, there seems to be a trend in warmer places, such as Houston," he said.

Hyponatremia means a low concentration of sodium in the blood. Sodium is a required element for normal body functions. Sodium (along with potassium and chloride) contributes to at least four important physiological functions:

1) water balance and distribution
2) osmotic equilibrium
3) acid-base balance and
4) proper muscle function

Even a slight depletion of sodium in the body can cause problems including confusion, agitation, vomiting, nausea, muscle cramps, slurred speech and inappropriate behavior. Severe hyponatremia can result in seizures, coma, and even death.

Jon Cianca, MD, Assistant Professor, Department of Physical Medicine and Rehabilitation at Baylor College Of Medicine and Medical Director for the Compaq Houston Marathon says that hyponatremia is most likely a result of the combination of the following:

1) Exposure to extreme heat.
2) Exposure to extreme heat for long periods of time. Athletes who participate in ultra distance events that take place in hot, humid conditions are at risk for hyponatremia. So are people who work outdoors for long periods of time.
3) Profuse sweating. Studies have shown that athletes can lose two or more grams (2,000 milligrams) of salt per liter of sweat. Considering that an athlete may lose up to a liter or more of sweat per hour, long endurance events can easily result in excessive losses of sodium.

"These three situations plus overdrinking water can cause hyponatremia," said Cianca. "When athletes replace lost fluids with water, they contribute to the decreased blood sodium concentration causing hyponatremia. Sports drinks have sodium but not enough to compensate for the sodium lost through sweat."

Dr. Cianca stated that inexperienced and less than optimally conditioned athletes are more likely to experience hyponatremia than experienced well-trained athletes. "I believe that experienced athletes are more adept at hydration techniques and their bodies are better acclimated to the heat," he said. "In short, they are more efficient."

Dr. Chorley added that there might be a correlation to hyponatremia and the use of anti-inflammatory medicines. "These meds might cause the kidneys to hold on to more water than they are supposed to," he said. "In addition, women might be more at risk for hyponatremia than men."

Mild forms of hyponatremia can be treated by consuming salty foods with a sodium containing sports drink, however, if the symptoms do not go away, a medical professional should be seen. "More moderate and severe cases need immediate medical attention," said Dr. Cianca. "If an athlete thinks they have hyponatremia, he/she needs to go to the emergency room so that cerebral and pulmonary functions can be closely monitored."

As always, the best cure is prevention. The best way for athletes to avoid hyponatremia is to plan ahead. Dr. Cianca recommends:

  • Training with a sodium containing sports drink. "When you are training, you have to be smart with how you hydrate," he said. "If you only drink water, you can make the situation worse."
  • If possible, eat salty foods before, during, and after training and competition. "Most athletes are not hypertensive, therefore, it is appropriate to add salty foods and liquids to one’s diet," he said.
  • Understand your individual fluid needs. "Listen to your body – don’t drown your body with water," he said.
  • Increase salt intake several days before endurance training or competition.
  • Progress slowly in regards to running a marathon or other endurance event. "Physically you can get ready in six months," he said. "Physiologically it may not be possible."

"Athletes respond differently to exercise and hydration, and fluid and sodium needs vary accordingly," said Dr. Chorley. "In order to minimize the risk of hyponatremia, it’s important for runners to listen to their bodies and monitor the amount of fluid and sodium that is being taken in," he said. "Stay hydrated throughout the day, but not too hydrated. Eat salty snacks and foods, especially if you follow a low sodium diet."

Foods that provide sodium include crackers, soups, cheeses, pretzels, tomato juice, and pickles. And as always, consult your physician or dietitian if you have any questions, concerns, or special considerations.

NOTE: A voluntary study is being conducted to better understand hyponatremia. If you are a novice runner and are participating in the 2002 Compaq Houston Marathon, your participation in the study might be needed. For more information, call Dr. Jon Cianca at 713-627-3156.

The Healthy Weigh •  6300 W. Loop South •  Suite 300 • Bellaire, TX 77401 • PH 713.622.6422
info@thehealthyweighonline.com