The Importance of Electrolytes for Endurance Athletes


The major role played by electrolytes for endurance athletes cannot be understated.  Keep reading more to learn about what electrolytes are, how to get more, and when to take them in.

‘Tis the Season for Heat

Good or bad, running outside is about to get hotter, and if you live where we do, more humid.  This means that our training sessions will be stickier and sweatier.  When you exercise in the heat, you sweat more, and in turn, lose electrolytes.  According to the American College of Sports Medicine (2007), on average, people lose 2 to 6 percent of their body weight during exercise sessions through sweating.

Ultrarunners and other endurance athletes should be even more concerned about maintaining electrolytes due to their intense and extended training durations.  If you aren’t familiar with what exactly electrolytes are and their major functions in the body, this next part is for you.  If you already know, well, read it anyway.


Electrolytes are chemicals that play a vital role in keeping us alive.  There are many automatic processes in our bodies that rely on the small current electrolytes create when dissolved in water.  Electrolytes interact with other electrolytes, nerves, tissues, and muscles.  They are responsible for regulating muscle and nerve function, hydrating the body, balancing the blood’s acidity, balancing blood pressure, and repairing damaged tissues.  There are five crucial electrolytes that play a critical role in exercise.


Sodium is a critical electrolyte for nerve function, which dictates muscle contractions.  Additionally, sodium helps regulate extracellular fluid (Strazzullo & Leclercq, 2014). The sodium content of foods is quite variable, depending on both the food source (animal foods tend to contain higher amounts) and how processed the food is (again, higher amounts).

Fruits and vegetables contain nearly negligible amounts of sodium.  Most of the food sources of sodium are cereals and cereal products, bread, meat products, and dairy (Strazzullo & Leclercq, 2014).


Chloride is a key electrolyte responsible for regulating body fluid distribution (Kataoka & Yoshida, 2020). After sodium, chloride is the most abundant electrolyte in blood serum (Berend et al., 2012). It maintains the levels of fluid both inside and outside of the cells.

Furthermore, chloride aids in maintaining proper blood volume, blood pressure, and proper pH levels of body fluids.  Foods such as seaweed, tomatoes, celery, lettuce, and olives contain chloride.  Chloride can also find it in many salt substitutes.


Potassium is responsible for the proper function of nerves and muscle contractions and aids nutrients in moving into and waste out of cells (CDC, 2021).   When people think of food sources of potassium, the most popular is bananas.  However, they are not actually the food with the most potassium.

Sweet potatoes and beets both have more potassium per serving than do bananas.  Other food sources are broccoli, mushrooms, cantaloupe, raisins, and dates.


One of the roles of calcium in the body, as it relates to exercise, is the regulation of striated (skeletal and cardiac) muscle contractions (Kuo & Ehrlich, 2015).  The muscle contraction cycle is triggered when calcium ions bind to troponin.  Food sources of calcium include yogurt, dark leafy greens, tofu, fortified cereals, and fortified milk such as soy, almond, or rice milk (USDA, 2019).


I will give you one guess as to the role of magnesium in exercise.  You guessed it.  Magnesium plays a role in the regulation of muscle contractions (Zhang et al., 2017).  This electrolyte acts as a natural calcium blocker to help muscles relax from a contracted state.

Magnesium is present in many green leafy vegetables, legumes, seeds, nuts, and whole grains.  Some cereals and other foods are also fortified with magnesium.  It would be best to be cautious about eating processed foods like refined grains because this reduces magnesium content significantly.

Signs of Electrolyte Imbalance

When the amount of electrolytes in your body is too high or too low, you can develop:

Dehydrated Runner

  • Dizziness
  • Muscle Cramps
  • Irregular Heartbeat
  • Mental Confusion
  • Fatigue/Lethargy
  • Nausea/Vomiting
  • Diarrhea or Constipation
  • And in severe cases, convulsions or seizures

Any of the above-mentioned symptoms can be bad enough to take you out of competition.  The most common sign of low electrolytes is muscle cramping, which can be excruciating and debilitating.

If you’ve never experienced these, consider yourself lucky.  I remember being at one of my husband’s races and seeing a guy on a stretcher with all his muscles completely locked up due to cramping.  He was screaming in agony…yikes.

Isn’t Water Enough?

While drinking water is a great way to stay hydrated, ultrarunners and other endurance athletes must be careful of just drinking plain water and not taking any electrolytes.  This can lead to a very dangerous called hyponatremia (low blood sodium levels). When you are running in the heat for a long period of time during an ultramarathon or a triathlon and losing large amounts of sodium through sweat, the risk of developing hyponatremia increases.

Training for ultramarathons and other endurance events is already taxing on the kidneys without proper care. When you add in the toll that an electrolyte imbalance can take, the results can be devastating.

The symptoms of hyponatremia can include:

  • Nausea and Vomiting
  • Headache
  • Drowsiness and Fatigue
  • Muscle cramps
  • Confusion
  • Irritability
  • Seizures
  • Coma

Obviously, some of these symptoms are life-threatening.  Even scarier is that these symptoms can progress rapidly.  Keep reading to learn more about what you can do to prevent hyponatremia.

Hydrated RunnerGood Practices to Follow

Below are a few good practices to follow during training sessions, especially during hot months.

  • Take precautions during high-intensity activities and training sessions, especially in the heat and humidity.

    • Athletes should drink only as much fluid as they lose due to sweating during a race. For most, thirst is generally a good guide to how much water or other fluids you need.


  • Consider drinking sports beverages during extended training sessions and competitions.

    • Ask your doctor about replacing water with sports beverages that contain electrolytes when participating in endurance events such as ultra-marathons, marathons, triathlons, and other demanding activities. Some people use an every-other-type method when hydrating (Drink some water then drink a sports beverage).  There are also gels and chews made to provide calories and electrolytes during activity.
  • Drink water in moderation.

    • That seems counterintuitive, but really…it’s a thing.  Drinking water is vital for your health, so make sure you drink enough fluids. But don’t overdo it. We already talked about this above.  Drinking too much water is dangerous.  Thirst and the color of your urine are usually the best indications of how much water you need. If you’re not thirsty and your urine is pale yellow, you are likely getting enough water.
    • In an extended duration training session or a race, this is also true.  If you aren’t urinating or your urine is dark, you are probably already in trouble.  It is easier to stay ahead of the hydration curve than to wait until you show dehydration symptoms.

Good Sources of ElectrolytesElectrolytes for endurance athletes

Coconut water is a good drink for replenishing electrolytes.  However, sports drinks are often more appealing to many people’s pallets. Sports drinks contain electrolytes and carbohydrates, which replenish energy. In addition, many sports drinks have sodium chloride, or potassium chloride added to them, which are major electrolytes lost when exercising.

The added sugar and flavor in these drinks often entice people to drink a larger quantity than water.  As I previously mentioned, there are also gels and chews created for athletes to aid in electrolyte replenishment as well.  Another great way to get more electrolytes is to eat a well-balanced diet of the aforementioned foods.

When Should Athletes Consume Electrolytes?


When you think of prehydrating, please don’t think of it as drinking a bunch of water or electrolytes right before you run.  That’s probably not the best idea.  The main goal of prehydrating is to ensure that you start your activity in a well-hydrated state with a good balance of electrolytes.  Many athletes are actually dehydrated before they even begin exercising (Maughan & Shirreffs, 2010).  Obviously, this is not ideal.  Why would you want to start a training session already behind on your hydration status?

According to The American College of Sports Medicine (2007), prehydration with beverages, in addition to normal meals, should take place at least several hours before the planned activity to enable fluid absorption and to allow emptying of the bladder.  Drinking plenty of water throughout your day, and eating a well-balanced diet should provide adequate hydration and electrolyte balance.  The exception to this is if you have a pre-existing medical condition that affects your hydration or electrolyte balance.

Hydrating During an Activity

Hydrating during your activity is also important, especially for endurance athletes.  You should hydrate during an activity to prevent excessive dehydration and electrolyte imbalance.  The amount of sweat lost during activity varies greatly from person to person.  Thus, The American College of Sports Medicine (2007) advises a customized fluid replacement program that takes into account your specific needs.

As I previously mentioned, most people can base their fluid intake on their thirst level.  How much you need to drink to stay hydrated can depend on your prehydration levels as well. One rule of thumb that I have is that I always bring more water than I think I will need.  If you’ve ever run out of water on a hot, humid day with several miles to go, you get it.  Also, as previously mentioned, hydrating with beverages containing electrolytes can be more beneficial than hydrating solely with water.


Once you are done with your training activity or race, it is also important to replace the electrolytes you just lost during your activity.  You need to replace those electrolytes you lost and make sure you are properly hydrated for the next training session.  If not, you will likely see deficits in your training.  If you want to recover rapidly (<24 h) or if you become severely dehydrated, more aggressive drinking of fluids and consuming electrolytes should be encouraged (Shirreffs & Sawka, 2011).

Interestingly, research shows that the addition of carbohydrates and protein can promote hydration by influencing the absorption and distribution of water(Evans et al., 2017).  Immediately following a workout, you should drink to thirst and then drink a little more to make sure you stay hydrated.  Ensure that you do not drink too much too fast, as this can cause gastrointestinal distress, and nobody has time for that!

Not One-Size-Fits-All

Obviously, everyone is different and has different hydration and electrolyte requirements.  What works for one person may or may not work for the next.  Thus, an individualized strategy will take into account your pre-exercise hydration levels, as well as fluid and electrolyte needs before, during, and after a training session or competition (Maughan & Shirreffs, 2010).  You should listen to your body and create a hydration plan that works for you.  Obviously, you can adjust this plan based on what season you are training in.

TerminusHow Can We Help?

Here at Ultraverse Supplements, we know how important electrolytes are.  That is why we have included them in Terminus, our endurance recovery formula.  Our formula includes the following:

  • Sodium: 391 mg
  • Potassium: 257 mg
  • Chloride (as Sodium Chloride and Potassium Chloride): 581 mg
  • Magnesium Bisglycinate (TRAACS®): 100 mg
  • Calcium Carbonate: 125mg (140mg total Calcium)
  • Taking it even further, we have included 47g of carbohydrates and 15g of Protein to ensure you recover fast.

When you take Terminus after your workout, you will help your body replenish many of the electrolytes you lost, as is recommended.

Proxima C Endurance Fuel






We also offer an endurance fuel, Proxima C, which contains optimal amounts of electrolytes, in optimal forms.  Proxima C was created to fuel runners through the long-haul.  Here is a look at the electrolytes in Proxima C

  • Sodium (as sodium chloride and sodium citrate) – 310 mg
  • Chloride (as sodium chloride) – 330 mg
  • Potassium (as potassium phosphate) – 85 mg
  • Magnesium (as DiMagnesium Malate from Albion®) – 10 mg
  • Calcium (as DiCalcium Malate) – 25 mg

Along with this stellar electrolyte profile, Proxima C has a unique four-carbohydrate blend to help fuel your runs.  The addition of L-ornithine will help you in the heat too!


In my opinion, training in the heat of summer is never fun.  But, if we want to get better, we have to do it.  We need to make sure we are careful and stay hydrated.  Electrolytes play a large role in exercise, mostly through cellular fluid regulation and nerve and muscle contraction.  When you sweat, you not only lose water but electrolytes as well.  It is important to go into your training session already in a good state of hydration and electrolyte balance.

You can achieve this by drinking plenty of water throughout the day and eating a well-balanced diet.  Hydrating during your training session is also important.  You can drink a mix of water and electrolyte beverages, but make sure you don’t only drink water if you are an ultrarunner or other endurance athlete that trains for extended periods.  Drinking water alone without electrolytes can lead to a serious condition: hyponatremia.

After your workout session, make sure you rehydrate and take in some electrolytes.  Terminus is a great recovery drink.  It not only has the required electrolytes you need to replenish, but it also has carbohydrates and protein, which are crucial for proper recovery.  Hopefully, you learned something about how important hydration and electrolytes are.  Now get out there and enjoy the sunshine…but wear sunscreen!


American College of Sports Medicine, Sawka, M. N., Burke, L. M., Eichner, E. R., Maughan, R. J., Montain, S. J., & Stachenfeld, N. S. (2007). American college of sports medicine position stand. exercise and fluid replacement. Medicine and Science in Sports and Exercise, 39(2), 377-390. doi:00005768-200702000-00022 [pii]

Berend, K., van Hulsteijn, L. H., & Gans, R. O. (2012). Chloride: The queen of electrolytes? European Journal of Internal Medicine, 23(3), 203-211. doi:10.1016/j.ejim.2011.11.013 [doi]

CDC. (2021). The role of potassium and sodium in your diet. Retrieved from

Evans, G. H., James, L. J., Shirreffs, S. M., & Maughan, R. J. (2017). Optimizing the restoration and maintenance of fluid balance after exercise-induced dehydration. Journal of Applied Physiology, 122(4), 945-951. doi:10.1152/japplphysiol.00745.2016

Kataoka, H., & Yoshida, Y. (2020). Enhancement of the serum chloride concentration by administration of sodium–glucose cotransporter-2 inhibitor and its mechanisms and clinical significance in type 2 diabetic patients: A pilot study. Diabetology & Metabolic Syndrome, 12(1), 5. doi:10.1186/s13098-020-0515-x

Kuo, I. Y., & Ehrlich, B. E. (2015). Signaling in muscle contraction. Cold Spring Harbor Perspectives in Biology, 7(2), a006023. doi:10.1101/cshperspect.a006023 [doi]

Maughan, R. J., & Shirreffs, S. M. (2010). Dehydration and rehydration in competative sport. Scandinavian Journal of Medicine & Science in Sports, 20 Suppl 3, 40-47. doi:10.1111/j.1600-0838.2010.01207.x [doi]

Shirreffs, S. M., & Sawka, M. N. (2011). Fluid and electrolyte needs for training, competition, and recovery. Journal of Sports Sciences, 29 Suppl 1, 39. doi:10.1080/02640414.2011.614269 [doi]

Strazzullo, P., & Leclercq, C. (2014). Sodium. Advances in Nutrition (Bethesda, Md.), 5(2), 188-190. doi:10.3945/an.113.005215

USDA. (2019). Food sources of calcium.

Zhang, Y., Xun, P., Wang, R., Mao, L., & He, K. (2017). Can magnesium enhance exercise performance? doi:10.3390/nu9090946

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