Apply It: Take extra sodium
From the field: Both sweat rate and the amount of salt lost through sweat vary widely from person to person. Lim says losing 350–400mg per half-liter of sweat is typical; Gatorade’s Murray says it’s closer to 500mg. Either way, that’s a lot of salt. Heat and humidity result in even greater salt loss per hour. Although arriving at a concrete number for the amount of sodium a person loses involves lab testing, Lim says sports drinks in general have insufficient quantities to optimally hydrate most athletes. “No sports drinks we could find had the right amount of sodium, so we were adding back our own sodium,” he says. “If you’re losing that much salt in your sweat and you’re just drinking water, or you’re drinking a fluid that doesn’t have that same amount of sodium, you’re going to dilute the sodium in your bloodstream. And when that happens you can get some very funky problems. This is all in the category of hyponatremia.”
From the lab: Many studies show that taking sodium during long-lasting endurance exercise prevents athletes from losing weight, implying they become less dehydrated. Improved performance, however, isn’t always tied to ingesting a lot of sodium.
Do it: A 20-ounce serving of Lim’s Skratch Labs Exercise Hydration Mix has 366mg of sodium. Most individuals need between 500 and 1,000mg of sodium per hour. If you use another mix with less salt, supplement your sodium intake with electrolyte pills or by adding an effervescent electrolyte supplement such as Nuun to your drink.
Dr. Gatorade’s Take
Add more sodium: Agree
Gatorade’s Endurance Formula, which Murray helped create, contains 500mg of sodium in a 20-ounce serving. “There is absolutely nothing wrong with favoring sodium replacement over carbohydrate supply for endurance athletes,” he says. “There are lots of different ways to ingest carbs, but fewer ways to consume sodium in palatable quantities balanced with water intake.” So keep the salt coming; the experts agree on this one.