Do You Need to Replenish Electrolytes After Exercise?

Sports drinks may not be as necessary as you think


Sports drink companies love to tell us about how their beverages are fortified with electrolytes. Yet, they never care to share what they really are or why we might need more of them.

Electrolytes are important because in addition to other aspects of athletic performance, they aid with cellular functions and muscle contractions. When we sweat, electrolytes like sodium, potassium, calcium, and magnesium are lost in varying amounts.

"Large disturbances in electrolyte levels can be quite disastrous for performance, and even health," says Andy Blow co-founder and Sports Scientist at Precision Hydration and a Red Bull High Performance partner.

But do you always need a sports drink near by while exercising, and are there actually any benefits to replenishing lost electrolytes?

"There is definitely a benefit to using sports drinks in the correct circumstances," says Blow. "However for a lot of recreational athletes who are not exercising very hard, or for very long the benefits of a sports drink will be limited or non-existent. There is no 'magic' in any of these drinks, they are just a conveniently packaged way of delivering water, sugar and salt to your body for when it needs these things most."

When we sweat, the electrolyte lost in most significant quantities is sodium, which is why it's included in most sports drinks. However, Blow says that sports nutrition experts consider sodium replenishment a somewhat controversial topic.

"Some camps argue that it's entirely unnecessary and others swear by it, says Blow. "One of the possible reasons for this controversy is that sodium loss can vary quite dramatically between individuals as can sweat rates, so it could well be that those with high levels of sodium loss stand to benefit more than others when it comes to replacement."

According to Blow sodium concentration levels in sweat can show up to an eight-fold difference between athletes, which means that just like the very individualized rules of hydration, there's no one size fits all recommendation for electrolyte replenishment during exercise.

"There are only some guidelines you can try to follow and refine for yourself with trial and error," says Blow. "It is certainly fair to say that sodium only really needs replacing at times when sweat losses are very high and that many athletes report benefits like reduced incidences of cramping and better absorption of the fluids and calories they take in when sodium is added to drinks, or taken in additional supplements."

Depending on your personal perspiration rate and what sort of activity you're engaging in, Blow recommends ingesting anywhere from 200mg to 2000mg of sodium per hour during endurance events or when exercising at high intensities (especially in hot conditions), but warns that some trial and error will be needed in order to find out what works best for you.

"As a rule of thumb if you are someone who has a very high sweat rate, very salty sweat, or you often get muscle cramps you might want to try taking in larger amounts sodium to see if that helps," says Blow. "On the other hand, if you don't tend to sweat a lot, have no cramping issues and don't feel your sweat is too salty you may not want to be as aggressive."

More serious athletes who would like to gain an accurate picture of just how much sodium they might need can have their sweat composition analyzed at But for those exercising at a more recreational level Blow says that your body will let you know if you need to up your sodium intake.

"You will tend to get cravings for salty-tasting food," he says. "As a result if you take in some salty foods or electrolyte based drinks post-event and they are tasting really good then you probably need them and should keep topping up with them until you feel satisfied"

This is the second installment of our three part series on hydration featuring the expert insight of Andy Blow, co-founder and Sports Scientist at Precision Hydration and a Red Bull High Performance partner.

Part 1: How Often Should You Rehydrate During Exercise?
Part 3: How Much Water Should You Drink to Stay Hydrated?


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