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Do Electrolytes Actually Prevent Marathon Cramping? Do We Need to Replace Them at All?

Posted May 19 2014 6:00am

Pretty much any sports drink you can find on the market will have three main ingredients: water, sugar, and electrolytes.

The need for water is pretty self-explanatory—you sweat out a lot of it, you get thirsty, and your body instinctively urges you to take something to drink.

The weather and the intensity of your workout dictate how much and how often you need to rehydrate. But, luckily, thirst is a great indicator of when you need water.

As for sugar, if you’re doing a workout, long run, or race that takes you longer than 90 minutes, you’ll need sugar (or some other form of carbohydrates) to replenish your body’s fuel stores so you don’t slow down when you start running out of carbs to burn.

But, what about electrolytes? How necessary are they? And when should you consume them during training?

How necessary are electrolytes?

When we talk about “electrolytes,” we’re primarily referring to sodium ions, which make up the bulk of the non-water content of your sweat.

Sodium is what makes your sweat taste salty and it’s the primary constituent of the electrolytes lost in sweat.  Some potassium is lost in sweat as well, but potassium losses are about one-tenth of sodium losses.

According to traditional logic, if you’re losing electrolytes in your sweat, you need to replace them with a sports drink.

Some people have even suggested that rehydrating without replacing electrolytes lost in sweat can lead to hyponatremia, a dangerous medical condition where the sodium levels in your blood are too low.

But scientific research paints a different picture.

Although electrolytes are indeed lost in sweat, they are at a lower concentration in sweat than in blood.  So as you sweat more and become dehydrated, the sodium levels in your body rise, as the fractional losses of sodium have a concentrating effect.

Research on the amount of sodium lost in sweat

In a 2004 review article, Edward Coyle, a professor at the University of Texas-Austin cites research showing that, even in very long bouts of exercise, the amount of sodium lost in sweat is quite small compared to the body’s overall sodium reserves.

And a 2001 study by three scientists at the University of Iowa found that a sodium-free sports drink performed just as well as a traditional sports drink when it comes to rehydrating during exercise.

Tim Noakes, a professor at the University of Cape Town in South Africa, argues that electrolytes are never necessary, even during multi-hour races.  In his 2012 book, Waterlogged: The Serious Problem of Overhydration in Endurance Sports , he cites research showing that your body adjusts the sodium content of your sweat based on your dietary sodium intake.

Noakes’ research suggests that if you regularly run long workouts in the heat and have low dietary sodium intake, your body will lower the salt content of your sweat so you’ll never run out.

When it comes to hyponatremia, Noakes points out that even a sodium-containing sports drink can’t prevent a drop in blood sodium levels: because the sodium content of your blood is much higher than the sodium content of any sports drink, drinking too much will still dilute your body’s sodium levels.

Researcher Edward Coyle does not go quite as far.

In his review article, he concedes that sodium isn’t necessary in shorter workouts or races, but writes that “the inclusion of sodium in fluid replacement drinks has some theoretical benefits, and the addition of sodium poses little or no risk.”

Coyle recommends drinking something with sodium in it when your run stretches longer than two hours.

Final thoughts: Sports drink or water?

These are all interesting findings, but their practical implications are somewhat limited for runners.

Even if it’s theoretically possible to do just fine in a half or full marathon drinking a solution with carbs and water, it’s unlikely that the contents of sports drinks are going to change anytime soon.

If you are drinking Gatorade for the carbs, you’re getting the electrolytes along with it for the foreseeable future.

The good news is that there doesn’t seem to be any real harm in consuming electrolytes.  However, if you’re doing a short or moderate-length workout when it’s hot out, you don’t need to worry about replacing electrolytes when you rehydrate.  Just plain water is fine.

However, this does seem to indicate pretty clearly that heavy doses of electrolytes through products such as Nuun, salt sticks, and other electrolyte replacement options is unnecessary.

How to develop your optimal hydration strategy

This is the type of research that makes developing a solid nutrition plan so difficult.

It’s clear that simply drinking or fueling as much as you can isn’t the best approach when it comes marathon nutrition.

Despite conventional wisdom, loading up on electrolytes isn’t going to prevent cramping and pounding sports drinks to stay hydrated can leave your stomach feeling bloated.

Moreover, drinking more to try to replace electrolytes can mess with your carbohydrate intake and result in taking in too much sugar at one time, causing your stomach to actually slow down the rate it delivers glycogen to your working muscles.

So, what if I told you there was a comprehensive blueprint that takes uses the latest scientific research and makes it simple to calculate YOUR exact, specific fueling needs during the race and then provides an actionable, easy-to-follow prescription for how to practice, carbo-load, taper and execute your exact marathon nutrition strategy?

Luckily, now there is.

With the combined powers of our nutritionist, team doctor, head of running research and marathon coach extraordinaire (yes, we’re kind of like Voltron :) we created the first of its kind Marathon Nutrition Blueprint.

This Blueprint calculates for you exactly how much, when, and what products you need to fuel optimally during the race and provides you with specific, actionable information on how to practice during training, carbo-load, taper, and recover.

The Marathon Nutrition Blueprint is launching June 1st, just in time to help you prepare for your fall marathon.

If you want to see what the Marathon Nutrition Blueprint is all about, get special first-look access, and the have the opportunity to get our exclusive pre-launch bonuses, then signup for our launch list and join our FREE nutrition webinar.
Click Here to Join for Free

In this webinar, I’ll show you how to calculate your fueling, hydration and electrolyte needs to develop an individualized race nutrition plan to avoid the dreaded marathon bonk. Plus, I’ll give you a free peak inside to the nutrition blueprint (along with a special bonus).

I’ll be doing this webinar  two times per day from May 29th to May 31st, so click here to signup for the time and date that works best for you .

Look forward to seeing you then – Coach Jeff

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