Sports Drinks Aren’t Always Good for Hydration

Although sports drinks are designed to replenish hydration during and after exercise, some of them may be dehydrating, according to a new study.

Researchers in New Zealand analyzed 28 studies on the hydrating effects of different sports drinks and found that hypotonic sports drinks, which have a lower amount of salt and sugar, are the best for rehydration during long workouts.

Many popular sports drinks on the market, however, are either isotonic or hypertonic. While isotonic drinks have a similar concentration of sugar and electrolytes (salt) compared to the body, hypertonic drinks have the highest percentage of sugar and salt, which contributes to dehydration.

David Rowlands, PhD, a professor of nutrition, metabolism and exercise at Massey University and a lead author of the study, told Verywell that he was surprised that hypotonic sports drinks “outperformed the heavily marketed isotonic sports drinks.” 

It’s a misconception that isotonic drinks are the best for hydration, but choosing a workout beverage isn’t a one-size-fits-all solution, he said. The type of workout, duration of exercise, and environmental conditions all affect how someone should think about hydrating.

“Water is generally a good drink choice for most exercise up to 60-90 min,” Rowlands said.

How to Think About Hydration

Staying hydrated is key to keeping the body functioning properly. The amount of water each person needs is based on age, gender, and a variety of other factors. Experts generally recommend that women drink 11.5 cups of water per day and men have 15.5 cups to meet hydration needs.

Individual hydration needs can vary based on activity level. During a workout, our bodies sweat to help cool us down. Some athletes sweat more than others, especially if they’re working out in a hot or humid environment.

Many athletes turn to sports drinks to replenish the fluids lost by sweating. Sports drinks might be an appropriate choice in certain situations, especially if the individual doesn’t like the taste of water.

“If a person will not drink much plain water but they will drink some sports drink, then it makes sense that the sports drink is best for them,” Jackie Buell, PhD, LDN, a sports dietician for Ohio State Sports Medicine, told Verywell. “If you have an athlete who does not sweat much and they like water, they could be fine without a sports drink.”

Ultimately, she said, athletes should “be proactive, stay hydrated, and drink often enough to replace sweat loss.”

In addition to replacing fluids, athletes often choose sports drinks for the electrolytes they offer. Electrolytes are electrically charged minerals, including sodium, potassium, and chloride.Electrical charge will attract water and help the body maintain fluid balances, Buell explained.

She added that electrolytes can be helpful for sweatier athletes who need to replace the sodium lost while sweating. However, she emphasized that this is a highly individualized need that’s based on the athlete’s electrolyte status and sweat levels.

Pretzels can be a great mid-workout alternative to sports drinks, Buell added.

When Should You Consume Sports Drinks?

Researchers in the new study pointed to hypotonic sports drinks as the most hydrating beverage—even better than water—during an endurance workout.

But many athletes who consume sports drinks, regardless of the type, are not actively doing a 90+ minute exercise. Experts say that these drinks should be reserved for certain athletic events.

“Sports drinks were designed for competitive athletes to use during practice and sporting events. We’ve seen these beverages morph into being commonly consumed by the general public when not exercising,” Julie Stefanski, RDN, CSSD, a certified sports dietitian and spokesperson for the Academy of Nutrition & Dietetics, told Verywell.

“I encourage athletes to use these products once they have been exercising 60 to 90 minutes to maintain hydration and stable blood sugar levels,” Stefanski said.

These drinks can be more beneficial at the start of a workout when the weather is hot or humid. Water is the best option when you’re not exercising, unless your doctor recommends otherwise, she added.

“Everyone tolerates absorption of beverages differently,” she said, adding that many athletes can’t drink hypertonic drinks because these often lead to diarrhea.

Regardless of what type of drink ends up working best for an athlete, experts agree it is essential to maintain hydration and avoid becoming dehydrated.

“The body absorbs fluid better when it’s consumed in small amounts frequently rather than large amounts at one time,” Stefanski said. “Athletes should be encouraged to take frequent hydration breaks while practicing to develop good hydration habits.”