During periods of intense activity, your body releases an antidiuretic hormone called vasopressin that causes the body to retain water (by decreasing the amount of water that is expelled in urine). why does this make endurance athletes particularly vulnerable to developing hyponatremia?

Hyponatremia is a condition where the concentration of sodium is abnormally low in the body. Sodium acts as an electrolyte that helps in maintaining the amount of water in the body.

Extremely low amount of sodium in the body leads to weakness, headache, etc. During periods of intense activity body releases vasopressin hormone that helps body to retain water. Endurance athletes become vulnerable to developing hyponatremia because these athletes during water during strenuous exercises. This makes the concentration of sodium low in the body by diluting it with more water.This may lead to hyponatremia.