Swimmers, Sweat, and Why You Need Electrolytes

Almost every swimmer has been asked by a non-swimmer if they sweat during practice. The answer is a resounding, “yes, of course”. The problem is, swimmers tend not to notice their sweat production due to the aquatic environment, and as a result may be under-hydrating during and post-workout. Paying attention to your hydration is a simple and easy way to maximize your performance, so let’s dive in.

In the water, the obvious indicators of dehydration are less apparent—excessive sweating, dry mouth, overheating, etc., so it’s easy to forget to drink fluids steadily throughout practice. This dehydration can ruin an otherwise solid workout, and if left unchecked, can reduce your training capacity over the course of a whole season. In a slightly dehydrated state, as in 1-2% reduction in body weight through fluid loss, your perceived exertion goes up (how much work you feel you’re putting in), performance goes down, and emotional state becomes more variable (prone to being irritable, moody, fatigued, etc). Moreover, your post-workout recovery slows down when your fluid volume is at a suboptimal level for quick delivery of nutrients and oxygen to working muscle tissues and removal of waste products from the bloodstream. Basically, everything gets a little harder when you’re dehydrated.

Why are Electrolytes important for Elite Swimmers?

Electrolytes are positively or negatively charged ions that conduct electrical activity to perform various functions within the body. Electrolytes must be present in proper concentrations to maintain fluid balance, muscle contraction and neural activity. The kidneys control electrolyte balance by excreting or conserving them. Water is drawn to local concentrations of electrolytes, so it follows wherever they go. When you sweat, you’re losing electrolytes primarily in the form of sodium (Na+) and chloride (Cl-), so when you start to replace lost fluids, you should replace the electrolytes as well. Potassium (K+), Magnesium (Mg2+) and Calcium (Ca2+) are electrolytes also lost through sweat, albeit in lower amounts than sodium and chloride.

 How Much Electrolytes Do I Lose?

The presence of electrolytes in your sweat is why sweat tastes salty. Some athletes have saltier sweat than others due to simple genetic differences, diet, sweat rate, and heat acclimatization. Athletes who feel dizzy, lightheaded, or experience muscular cramping post-workout may be salty sweaters and have an electrolyte imbalance. If you only drink water to rehydrate, you could be diluting your internal electrolyte concentration and throwing your body further off balance. While the human body is good at regulating itself, elite training is strenuous and long enough that you must actively pump electrolytes in to support the rehydration process.

When Should I Replace Electrolytes?

Before Workout: If you are a “salty sweater” then you might consider drinking an electrolyte beverage or having a salty snack prior to a heavy workout (> 60 – 90 minutes) or one that is performed in hot temperatures.

During Workout: Sports drinks that contain sodium and carbohydrates are ideal during exercise. The sodium replaces electrolytes and helps the body utilize carbohydrates. Many sports drinks contain sugar in such high concentrations that athletes don’t feel comfortable drinking them mid-workout. You can 1) look for drinks that are lower in sugar (yet still avoid artificial sweeteners), 2) alternate between the sports drink and water during practice, or 3) choose a powdered electrolyte so you can control how concentrated your drink is.

Post Workout: It is easier to retain water in the body with the intake of salt, because water naturally follows those molecules. Ingesting salty foods or a sports drink can help you rehydrate faster than by drinking water alone.

Recommended Amount of Fluids and Electrolytes?

Within 60-90 minutes of exercise, athletes can lose around 1-2% body weight in the form of fluids. Your weight (say 150 lbs) multiplied by this percentage is the amount of fluid you should try to drink as a replacement (150lbs x 0.01 to 0.02 = 1.5 to 3 lbs bodyweight loss, or 24 to 48 fl oz). On hot days or with heavy sweaters, this number can increase.

For swimmers in the pool between 45-120 minutes, a beverage containing 60-120 mg sodium and 15-45 mg potassium per 8-oz serving will be effective for electrolyte replacement. Check the label to find your desired ratio of electrolyte to carbohydrate.


Electrolytes come in tablets, powders, gels, chews, blended sports drinks, table salt, food, and more. For the elite swimmer, sports drinks and powders mixed with water are common ways to ingest electrolytes, unless you require a higher concentration in the form of tablets or chews for endurance events. Whatever your method of choice, start using electrolytes during and post-workout to see how it affects your training. Over time you can calibrate your electrolyte intake to customize it for your recovery needs!

Find related articles on hydration and performance on our nutrition page at BridgeAthletic!

1. https://www.acefitness.org/certifiednewsarticle/715/electrolytes-understanding-replacement-options/

2. Sawka, Young, Cardarette, et al. 1985 http://www.humankinetics.com/excerpts/excerpts/dehydration-and-its-effects-on-performance

3. http://beta.active.com/nutrition/articles/cracking-the-code-on-sweat-rates

4. http://www.huffingtonpost.co.uk/2012/02/20/mild-dehydration-causes-a-_n_1288964.html
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BridgeAthletic Logo 3BridgeAthletic works with elite professional, collegiate, and club swimming programs to provide a turnkey solution for dryland training. Led by Nick Folker, the top swimming strength and conditioning coach in the world, our team builds stroke-specific, custom-optimized dryland programs for each of our clients. The individualized workouts are delivered directly to athletes via our state of the art technology platform and mobile applications. Check Nick and BridgeAthletic out as recently featured in SwimSwam.


Nick Folker, BridgeAthleticNick Folker is the Co-Founder and Director of Elite Performance at BridgeAthletic. Nick’s roster of athletes includes 35 Olympians winning 22 Olympic Medals, 7 team NCAA Championships and over 170 individual and relay NCAA championships. Megan Fischer-Colbrie works as the Sports Science Editor at BridgeAthletic. Megan was a four-year varsity swimmer at Stanford, where she recently graduated with a degree in Human Biology. The Championship Series by BridgeAthletic is designed to empower athletes with tips from the pros that will help them reach peak performance come race day. We will be covering competition-focused topics such as nutrition, recovery, stretching, and mental preparation.

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7 years ago

Full disclosure …I am on on Team Nuun…..could not agree more that many swimmers, especially in masters neglect fluid replacement during practice as well as before and after.
Many products to choose from out on the market. I happen to use Nuun products and have found them to be effective for me!