What is Hyponatremia?

Hyponatremia is a medical condition characterised by abnormally low levels of sodium in the blood. Normal levels of sodium in the blood range from 135 to 145 mmol/L. 

Sodium is essential for maintaining proper fluid balance and nerve function in the body. Hyponatremia can occur when there is excessive water intake, diluting the sodium in the body, or when there is a loss of sodium through sweating or certain medical conditions.

Athletes, especially those participating in long endurance or ultra events, may be at risk if they consume large amounts of water without adequate sodium replacement. Athletes should pay attention to replace both fluid and electrolytes (especially sodium) during exercise.

Many athletes are aware of the risks of dehydration, but hyponatremia can be just as dangerous. Symptoms of hyponatremia can range from mild to severe and may include nausea, headache, confusion, seizures, and in extreme cases, coma or death. 

Treatment often involves addressing the underlying cause and may include dietary adjustments, medical interventions, or intravenous saline solutions to restore the sodium balance.

An easy way to see if you have been over hydrating during training or an event is to weigh yourself just before the event, and right after you finish. If you weigh more at the end, it likely indicates that you have over hydrated. 

If you weigh the same, or your body weight is 1-3% less, you've likely done a good job of hydrating. 

Understanding and monitoring sodium intake and hydration levels can be crucial for athletes to prevent this condition. See how osmolality relates to this topic learn the difference between hypotonic, hypertonic and isotonic drinks.