Salt Needs of Ultra-Endurance Athletes

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High-salt (sodium) diets have been linked to a number of health risks in many Americans. However, some athletes, due to their increased activity and excessive sweat production, are actually at risk of having too little sodium in their bloodstream during training and competition.

Because sodium is lost in sweat, it is more important for individuals who exercise at high intensity to get adequate sodium before, during, and after exercise. This is even more critical during ultra-endurance competition. These types of athletes may have special sodium requirements.

Ultra Endurance Athletes and Low Sodium

Hyponatremia, a low concentration of sodium in the blood, has become more prevalent in ultra-endurance athletes. The Hawaii Ironman Triathlon, for instance, routinely sees finishers with low blood sodium concentrations.

During high intensity exercise, sodium is lost along with sweat. An athlete who only replaces the lost fluid with water will have decreased blood sodium concentration.

Consider a full glass of salt water. If you pour out half of it, then refill with plain water, the sodium concentration in the glass is far less. This can occur in the bloodstream of an athlete who only hydrates with water during excessive sweating, resulting in hyponatremia.

Adequate sodium balance is necessary for transmitting nerve impulses and proper muscle function. Even a slight depletion of blood sodium concentration can cause problems.

Ultra distance running events that take place in hot, humid conditions and have athletes competing at high intensity create conditions prime for hyponatremia to develop. Studies have shown that ultra-endurance athletes can lose 1 to 2 grams of salt per liter of sweat.

If you consider that these athletes may lose up to a liter (or more) of sweat each hour, you can see that over a long endurance event (such as a 12-hour race), they could sweat out a huge amount of sodium. Replacing this loss during the event is critical to performance and safety, especially in hot weather.

Signs of Low Sodium

The early warning signs of low blood sodium levels are often subtle and may be similar to dehydration. They include:

At the most extreme, an athlete with hyponatremia may experience seizures, coma, or death.

Because of the similarity in symptoms, many athletes at risk of hyponatremia drink water because they think they are dehydrated. But consuming water alone (without also consuming sodium) worsens the problem.

How to Keep Sodium Levels Healthy

Consult your physician if you have a history of health problems, such as hypertension, or are taking medication for a health condition. Otherwise, the best way to avoid hyponatremia is to plan ahead.

  • Consume sodium-containing sports drinks during long-distance, high-intensity events.
  • Eat salty foods before and during competition. Foods that provide additional sodium include chicken broth, dill pickles, cheese, pretzels, and tomato juice.
  • Increase salt intake several days prior to competition. The increased sodium concentration will allow additional hydration with water to remain balanced so that dilution of blood sodium does not occur.
  • Weigh yourself before and after training and drink enough sodium-based sports drink to offset any fluid lost during exercise.

Also, avoid use of aspirin, ibuprofen, and other non-steroidal anti-inflammatory drugs, as they may increase the risk of hyponatremia in athletes. Additionally, chronic use of these medications often mask the body's own warning mechanisms that alert athletes to pain and injury. Many triathletes take these medications without knowing of their detrimental effect on performance.

As there are no steadfast guidelines for everyone, it is important to understand how your size, activity level, and other factors influence your individual hydration and sodium needs. Keep in mind that all athletes respond differently to exercise; fluid and sodium needs will vary accordingly.

What to Do If Your Sodium Gets Too Low

At the first sign of nausea, muscle cramps, or disorientation, an athlete should drink a sodium-containing sports drink, such as Gatorade, or eat salty foods. If the symptoms are extreme, a medical professional should be seen.

If possible, plan ahead and estimate your fluid loss and need for sodium replacement during an event. It's also helpful to stay on a hydration schedule during the race.

6 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Elizabeth Quinn, MS
Elizabeth Quinn is an exercise physiologist, sports medicine writer, and fitness consultant for corporate wellness and rehabilitation clinics.