﻿ Ask the Experts: Staying Properly Hydrated During Exercise on MedicineNet.com

Fitness: Staying Properly Hydrated During Exercise (cont.)

Although hyponatremia is a serious condition that should be avoided, some sports medicine professionals believe we may have gone overboard in our warnings to athletes to make sure they drink enough. In a study conducted at the Boston Marathon, 62 out of 488 runners who consented to have their blood tested after the race had hyponatremia, and three of them had critical hyponatremia. The incidence was highest in (1) the leanest runners, (2) those who ran slowest (more than four hours completion time), (3) those who consumed more than 3 liters of fluids during the race, and (4) those who consumed fluids every mile. The slowest runners are probably susceptible because they run slow enough to consume every drop of water in the cup, whereas faster runners typically spill fluid because they run so fast, and they also may skip water stations to maintain speed. The lesson here is that one must drink to maintain fluid balance but not so much that fluid needs of the body are exceeded.

Both hyper- and hypohydration are conditions that can and should be prevented. I suggest weighing yourself nude before and after your workouts to determine how much fluid you lose and then replace those fluids as per the NATA guidelines. A liter water of water weighs 2.25 pounds and so you can make your calculations based on that information.

Take care, and thank you for your question.

Last Editorial Review: 3/5/2007