Ask The Coach: How Should I Approach Salt Consumption During Ultras?

We know we lose a lot of sweat when we run, especially the extreme distances of ultramarathons. So how should you strategize salt replacement?

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In our column, “Ask the Coach,” we answer your burning questions about all things trail running! Nutrition, workouts, gear….chafing? We’ve seen it all. In this installment: what’s the deal with taking salt tabs during ultras, and can you take too many? Read on to find out, and scroll down to find out how to submit your own ATC questions!

I am currently training for my second 50K and first 50-miler. I’d like to know when and how often to take salt tabs. And is it possible to overdose?

—Keith P, Canandaigua, NY

Salt consumption is a topic that recent research has thrown into contention. I’ve witnessed athletes with debilitating muscle cramps turn their whole day around by taking salt tablets. Yet, research championed by Dr. Timothy Noakes, author of Waterlogged: The Serious Problem of Overhydration in Endurance Sports, seems to indicate that our bodies have plenty of on-board electrolytes for endurance endeavors. I tend to hedge my bets—since most of this recent research was done on marathon or shorter distances—and believe we need less than previously thought.

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It’s difficult to prescribe exactly when and how much salt each person should take, since each athlete has unique biological requirements. “As a general guideline, for light sweaters or smaller individuals, consider about 200 milligrams of sodium per hour. For heavy sweaters, larger individuals or in hot conditions, consider 400 to 600 milligrams or more per hour,” says Jonathan Toker, Ph.D. and developer of SaltStick. It’s going to take trial and error to figure out what your range is. Practice on your long runs, since they typically mimic race conditions most closely.

If you are worried about overdosing it might be worth the cost of getting a professional to test you, or visiting your doctor for guidelines. In the United States, the Recommended Daily Allowance of sodium is 2,400 milligrams. However, on days you train or race, you can go through far higher levels.

Says Toker, “A 2010 study, Sweat Rates, Sweat Sodium Concentrations, and Sodium Losses in Professional Football Players, showed sodium loss ranged from 642 milligrams per hour to a stunning 6.7 grams per hour.” The symptoms of over consumption are similar to those of under consumption, and include cramping and fatigue. Start with a moderate amount on hot days and see how you feel; your body will tell you if you need more.

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Have a training question for the coach? Email your questions to with the subject line “Ask the Coach”.

This article originally appeared in our October 2014 issue.

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