Exercise-Associated Hyponatremia: Who's at Risk?

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We've all learned that fluid replacement is critical to replace fluids lost when exercising, but drinking pure water exclusively isn't the safest choice for those who participate in very strenuous or long-duration exercise.

When significant amounts of fluid are lost through high-intensity exercise, replacement with water alone can lead to a chemical imbalance in the body and deficiencies in electrolytes, which are nutrients critical for organ functioning. The electrolytes in our body include sodium, potassium, chloride, calcium and phosphate, but sodium is the substance of most concern when replacing fluids lost through exercising.

Hyponatremia is a condition in which the body's stores of sodium are too low, and this condition can result from drinking extreme amounts of water. Hyponatremia can lead to confusion, lethargy, agitation, seizures, and in extreme cases, even death. Early symptoms are nonspecific and subtle and may include disorientation, nausea, or muscle cramps. The symptoms of hyponatremia may also mimic those of dehydration, so athletes experiencing these symptoms may be given more water to drink, further worsening the condition.