Electrolytes 101

Sweating It Out

And for most endurance athletes, therein lies the rub: If you're already trying to re-hydrate and take in fuel for energy, how do you work electrolytes into the equation?

First, it helps to understand that when we sweat we lose electrolytes—mainly sodium—as well as water. But because we lose water faster than we lose electrolytes, it's not critical to replace lost minerals during shorter (less than one hour) workouts.

More: Measure Your Sweat Loss for Optimal Hydration

During shorter workouts the body's electrolyte concentration actually increases, according to Joel Mitchell, chair of Texas Christian University's department of kinesiology. Mitchell says the kidneys then act to filter out any "extra" electrolytes to correct the imbalance.

However, longer workouts can empty your body of large amounts of sodium and other important electrolytes. When electrolyte levels drop too low, severe loss of neuromuscular function can incur along with increased blood acidity (fewer electrolytes are available to neutralize the lactic acid your muscles are producing). In essence, your body begins shutting down.

Effective Replacement

It's important to replace fluids as well as electrolytes even if you don't feel thirsty, explains Leslie Bonci, director of sports nutrition for the University of Pennsylvania Center for Sports Medicine and a member of the Gatorade Sports Science Institute's Sports Nutrition Board. This is especially true in colder weather when you may not notice sweat or fluid depletion as quickly.

Luckily, replenishing lost electrolytes isn't difficult, and because electrolyte balance is tied to hydration (remember, electrolytes need water to do their job), sports drinks are often recommended as the most efficient form of replenishment, although sports gels may also do the trick.

"Sports drinks are designed to provide adequate amounts of key electrolytes, and they also deliver the added benefit of providing carbs for energy and water to supplement hydration," says Bonci, who recommends looking for drinks that deliver key minerals like sodium and chloride, the two electrolytes we lose most through sweat.

Sports drinks also help take the guesswork out of deciding how much of each electrolyte you need since they're calibrated to return average amounts of electrolytes.

More: The Truth About Sports Drink After Exercise 

But just like with pre-race rituals and training approaches, there's an element of personal preference when it comes to electrolyte replacement. So try different products until you find the ones you like best.

Bonci advises, "If you're a 'salty sweater' (your sweat stings, tastes salty or leaves a white residue on skin or clothing), or if your workouts or races are extending well beyond the two-hour mark, you may need more sodium and chloride than a sports drink alone can supply.

More: Stay Hydrated with High Water Content Foods

In this case, experiment with energy gels (carbs and electrolytes) or electrolyte capsules or tablets in addition to your sports drink, especially if you're training for major endurance events such as a half Ironman, Ironman or ultramarathon.

For less extreme distances, however, Bonci says athletes will do fine using a sports drink and possibly including higher sodium items like tomato juice, soups, baked beans, pickles and pretzels in their diet in the days leading up to an extended workout or race.

How Much Do I Need?

The typical athlete needs to consume a minimum of 20 to 40 fluid ounces per hour, and you should make sure you're using a sports drink that contains at least 250 mg of sodium per 20 ounces (100 mg per 8 ounces) in activities lasting more than an hour, advises Bonci.

These drinks will also contain the other main electrolytes, like chloride and potassium, in the right amounts. If you're doing an especially long workout (more than two hours) or you sweat a lot of salt, look for sports drinks that supply 500 mg of sodium per 20 ounces. You should replace lost electrolytes at a rate of 250 to 500 mg per hour if you hydrate at the recommended rate.

Likewise, electrolyte capsules offer similar ratios of electrolyte to fluid, while gels offer more concentrated amounts but need to be taken with water. If you're unsure about your electrolyte replenishment needs, especially if you're training at a higher endurance level for the first time, consult a sports nutritionist for guidance.

More: How to Create a Race-Day Hydration Plan

Emma Williams is a freelance writer specializing in health and nutrition writing and a mid-distance triathlete based in Chattanooga, Tenn.

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