Credit: Pinswept, https://commons.wikimedia.org/wiki/File:Boston_marathon_mile_25_gatorade_volunteer_050418.jpg, image cropped for straightening

Deadly Overwatering

If you were asked whether a world-class athlete should pre-hydrate, drinking water even before they become thirsty, you’d probably say, “Sure. Can’t hurt, right?” A recent study reported by the New England Journal of Medicine says that it actually can.

Drinking too much water, becoming overly hydrated, can lead to hyponatremia. Hyponatremia can deplete sodium, which is needed for cells to function properly, which in turn can lead to death.

The report studied nearly 500 Boston Marathon runners, and here are some of the findings.

  • The range of millimoles of sodium per liter of blood is considered normal between 135 and 145.
  • Of the 488 runners who were studied, 65 finished with hyponatremia.
  • For runners with normal sodium levels at the end of the marathon:
    • 54% drank every mile
    • 26% drank three or more liters
    • 29% weighed more from fluid intake at the end of the race
  • For runners with hyponatremia at the end of the marathon:
    • 75% drank every mile
    • 42% drank three or more liters
    • 71% weighed more from fluid intake at the end of the race

As you can see from this sampling, drinking too much water greatly increased the chances of hyponatremia. Moral of the story? Stay hydrated, but not too hydrated.