Why Electrolyte Drinks May Prevent Cramps for Runners Better Than Pure Water

Hydrating while running
Hydrating while running.

 Yellow Dog Productions/Getty Images

If you get muscle cramps when you run, electrolytes my be the answer. In fact, research published in Journal of the International Society of Sports Nutrition shows that plain water may not be the best way to rehydrate, and that electrolyte beverages are a better option to help decrease muscle cramps.

The study focused specifically on exercise-associated muscle cramps (EAMC), which are painful, involuntary muscle contractions. While the exact cause of EAMC are likely to be multifactorial, previous studies have shown that dehydration and low electrolyte levels may contribute to this painful condition.

“Exercise associated muscle cramps (EAMC) are cramps occurring during and/or after exercise and sports,” says professor Ken Kazunori Nosaka, director of exercise and sports science at Edith Cowan University in Joondalup, Australia, and a researcher on this study.

“It has been reported that muscle cramps are experienced by many people, including around 39% of marathon runners, 52% of rugby players, and 60% of cyclists” says Nosaka.

What the Research Says

In this study, the researchers compared EAMC susceptibility with runners who were drinking spring water vs. an electrolyte beverage. The study participants included ten men who ran in the heat for 40-60 minutes and ingested one of these two beverages.

The amount that runners drank during exercise was 918–1741 ml for water and 903–1848 ml for the electrolyte beverage, so the amount of fluid is comparable. The difference lies in the addition of electrolytes. The electrolyte-rich beverage contained the following:

  • Sodium - 1150 mg/L
  • Potassium - 780 mg/L
  • Magnesium - 24 mg/L
  • Chloride - 1770 mg/L
  • Glucose - 18,000 mg/L
  • Phosphorus – amount not specified

Nosaka and the research team electrically stimulated leg muscles to induce muscle cramping, and the frequency of the stimulation was used as an indicator of muscle cramp susceptibility. This was done before, immediately after, 30 minutes after and 65 minutes after running.

Runners were tested with each beverage, and these two conditions were separated by a week. The researchers also took blood samples to assess levels of electrolytes.

Water vs. Electrolytes for Cramp Prevention

Research has shown that drinking water during exercise in the heat increased muscle cramp susceptibility after exercise while drinking an electrolyte beverage decreased the muscle cramp susceptibility and may be effective for preventing EAMC.

Blood test results also showed that sodium and chloride concentrations decreased immediately post-run for the spring water drinkers, but not for those consuming the electrolyte beverage.

Ken Kazunori Nosaka, PhD

If runners are prone to muscle cramps and are taking fluid during training or races, it is better to consider taking water containing electrolytes, especially sodium and potassium.

— Ken Kazunori Nosaka, PhD

“If runners are prone to muscle cramps and are taking fluid during training or races, it is better to consider taking water containing electrolytes, especially sodium and potassium,” says Nosaka. “If drinking too much plain water, muscles will become more susceptible for cramping."

The research team noted that blood plasma volume was greater for the runners drinking the electrolyte beverage, suggesting that the electrolytes may help increase water absorption.

Hydration and Sport

From cycling to running to Ironman competitions, performing sports in hot temperatures is common. Sweat is lost during physical activity, and exercising in the heat increases the body’s core temperature. This reduces water content in the body, which can lead to dehydration if fluids are not properly replenished.

"Proper hydration practices help reduce the risk of dehydration and heat illness, and improve performance during exhaustive exercise," says Heather Mangieri, a sports and wellness dietitian in Pittsburgh and author of "Fueling Young Athletes." 

She explains that even slight dehydration can negatively impact the body’s ability to cope with physical activity, especially in warmer temperatures.

"Guidelines for how much fluid and/or electrolyte replacement beverage to drink before, during and after physical activity are meant to support health and sports performance," says Mangieri. She suggests:

  • Athletes should consume about 20 ounces of fluid in the 2 to 3 hours before activity and another 8 ounces in the 10 to 20 minutes before starting.
  • During activity, the goal is to match fluid intake to what is lost in sweat and urine. As a general rule of thumb, athletes should consume around 8 ounces of fluid every 15 to 20 minutes.
  • After activity, athletes need to rehydrate and replenish lost electrolytes.
  • In competitive athletes, the recommendation for what to drink after exercise is based on the amount of weight lost from fluid loss. Ideally, athletes should try to drink 1.5 liters of fluid for every kilogram of body weight lost.

Water vs. Electrolyte Drinks

For athletes, the goal of fluid intake is to prevent dehydration and changes in electrolyte balance during and after exercise. So, should you choose water or an electrolyte beverage for that?

"As a general rule, athletes that participate in continuous activity for more than one hour may benefit from drinking an electrolyte-rich sports drink," says Mangieri. "Heavy sweaters, and salty sweaters may benefit from a sports drink even in shorter duration activity, especially if it’s performed in hot and humid conditions."  

Heather Mangieri, MS, RDN

As a general rule, athletes that participate in a continuous activity for more than one hour may benefit from drinking an electrolyte-rich sports drink.

— Heather Mangieri, MS, RDN

Adding electrolytes to water helps maintain fluid balance due to its effect on extracellular fluid osmolality and volume. Studies show that drinking too much plain water while exercising can result in hyponatremia, which is a condition when there’s not enough sodium in the blood. Too much water dilutes serum sodium and other electrolytes, which can increase susceptibility of feeling muscle cramps.

One review of studies on this topic showed that athletes performing in high temperatures and losing a lot of sweat may be at risk of EAMC if they drink plain water. Athletes who drink electrolyte-rich beverages may be less likely to suffer with muscle cramps.

Understanding Muscle Cramps

Past studied have noted a link between low serum sodium concentrations and muscle cramps, so it’s important to study this mineral in athletes during different sporting conditions.

Interestingly, some studies have not supported the link between low serum sodium and EAMC. It’s an area that requires future research, and the cause of EAMCs is still being debated among scientists. 

"Dehydration and electrolyte imbalances are one of the most widely discussed theories for why exercise induced muscle cramps occur, but cramps can be due to physical conditioning, overexertion or other causes as well," says Mangieri. 

The present study says that muscle cramp susceptibility is not determined by serum sodium and chloride concentrations alone. Some researchers believe that muscle cramps stem from neurological origins, and include muscle overload and fatigue.

Mangieri says that athletes who do notice an uptick in EAMCs related to fluid and sodium intake should increase consumption of salty snacks and beverages to help stimulate thirst, increase voluntary fluid intake, and decrease the risk of hyponatremia.

"That means consuming sports drinks in place of water and eating salty foods and snacks like pretzels, crackers, soups and olives," says Mangieri. "I’ve even had clients drink chicken broth and eat pickles before long distance endurance events." 

A Word From Verywell

If you are exercising in the heat and sweating a lot, consider drinking an electrolyte beverage rather than plain water. The fluids and electrolytes may help prevent exercise-associated muscle cramps, which can hinder your athletic performance. 

9 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Cara Rosenbloom, RD
 Cara Rosenbloom RD is a dietitian, journalist, book author, and the founder of Words to Eat By, a nutrition communications company in Toronto, ON.