If you've ever run a 5K, competed in a triathlon, or even just attended a kids' soccer game, you've seen athletes swigging bottles of neon-colored sports drinks. Grocery stores are glutted with products in a rainbow of flavors, from Mountain Berry Blast to Glacier Freeze, all claiming to be scientifically formulated to replace lost electrolytes and improve your performance before, during, and after exercise. But how much do you really need them?
While some studies support the idea that athletes should consume carb-heavy drinks, this idea isn't supported across the board. So we spoke with exercise scientists and medical professionals to find out if sports drinks ever really make sense (and if so, when)—or if they're nothing more than glorified sugar bombs.
Electrolytes are minerals—primarily sodium, potassium, calcium, chlorine, magnesium, and phosphates—that are in our blood and other body fluids. They have electrical charges and work to activate the electrical tissues of our bodies, including muscles and nerves. "Roughly, electrolytes keep our system functioning," Barry Popkin, Ph.D., a food science researcher and professor of nutrition at UNC-Chapel Hill, tells SELF. Most major organs help regulate our electrolyte levels, and when they're correctly balanced, our blood chemistry runs as it should.
But sometimes we lose too many of them and need to replenish our supply. Usually, this happens in cases of serious dehydration due to illness. Since the minerals are in our bodily fluids, losing a lot of them at once causes electrolyte levels to drop. However, we can also lose significant water and electrolytes through sweat.
Sodium and other electrolytes are needed to create the electrical impulses that regulate nerve and muscle function. When we get too little, those signals aren't sent properly and the body can't run as smoothly as it should, resulting in cramping, dizziness, and headaches, among other symptoms. "Not getting enough sodium in fluid replacement can lead to complications like heat cramps, heat illness, and decreased performance," Mary Jane Detroyer, a registered dietitian, exercise physiologist, and personal trainer, tells SELF. At its most extreme, dehydration can lead to seizures or hypovolemic shock, a drop in blood pressure that decreases the body's oxygen, which can be fatal.
Our fluid and electrolyte losses really depend on our individual bodies, as well as the conditions we work out in, Ron Maughan, Ph.D., emeritus professor of sport and exercise nutrition at Loughborough University in the U.K., tells SELF. Exercise duration and intensity, environmental temperature and humidity, fitness level, weight, and how much we tend to sweat all play a part.
To put it in perspective, Detroyer says that when we perform light exercise in a dry, cool environment, we're likely to lose only about 250 milliliters of fluid an hour, whereas if we exercise in a hot, humid environment, we can lose 2 or even 3 liters an hour.
The primary electrolyte we all lose through sweat is sodium, but the amount varies from person to person. "Different individuals can lose anywhere between 20 to 100 mmol or mEq [a unit of concentration] per liter of fluid lost," Detroyer says, noting that we lose far less potassium—only about 10 mmol/L. The rest of the minerals that make up our electrolyte cocktail are lost at even smaller rates.
In athletics, hyponatremia can be caused by not drinking enough and letting your sodium concentration get too low, or overhydrating—all of the water dilutes the sodium concentration in your bloodstream. Hyponatremia happens when your sodium concentration drops below 135 mEq/L. Of course, you're not measuring how much fluid and sodium you're losing from a workout, so the way you'd know is by looking out for symptoms.
Unfortunately, the symptoms can look a lot like those of dehydration—nausea, confusion, and irritability—which can lead to inappropriate treatment. At its most severe, hyponatremia can cause the brain to swell and can be fatal.
You're more likely to become dehydrated than overhydrated, so a good rule of thumb is to drink when you're thirsty and don't force yourself to chug water if you're not.
The first sign that you need to drink more fluids is thirst. Easy enough.
The American College of Sports Medicine gets more specific, suggesting weighing yourself before and after exercise to estimate how much fluid you personally lose through sweat. A difference of more than 1 percent indicates dehydration, it says, and should be made up for before, during, and after exercise through a hydration plan. Detroyer is on a similar page. "Weight loss of more than 1.8 percent of body weight impacts performance," she says. "The goal should be no weight loss, by hydrating properly before, during, and after."
However, not everyone believes that this is the best approach. "I disagree completely," Timothy Noakes, M.D., D.Sc., author of Waterlogged: The Serious Problem of Overhydration in Endurance Sports, and emeritus professor in the division of exercise science and sports medicine at the University of Cape Town in South Africa, tells SELF. "There is no scientific basis for this advice. The only advice athletes need is: Drink to thirst. Not more, not less."
Noakes says that people have been encouraged to overhydrate by the sports drink industry—he's far from the only expert who suggests this. His advice? Drink water until you're no longer thirsty, or not more than about 2 cups an hour. If you suspect you're at risk for overhydration, swap fluids for something salty.
Let's be real. Chances are, you're not weighing yourself after every workout (nor should you be). Beyond regular old thirst, there are a few other signs that may let you know it's time to hit the H2O a little harder. "If your performance is strong and you're not having muscle cramps, you're doing fine," Detroyer says. "But if your urine is really dark, or if you add an extra minute onto your mile without any other reason, those are signs that you should consider drinking more fluids." If you're cramping, she says that's a sign your body needs more sodium.
All of the experts we spoke to promoted drinking plain water, especially for relatively light exercise. "If you go to the gym, do 60 minutes of activity, and you're not a heavy sweater, you don't need anything more than water," Detroyer says. A sports drink just adds extra calories and sugar.
When you're exercising intensely for more than an hour, or if it's really hot out and you're sweating bullets, you're losing a lot more fluids and electrolytes than you would in a standard visit to the gym. Most experts recommend replenishing fluids and electrolytes (sodium, specifically) throughout.
Popkin acknowledges that endurance athletes may want that boost of sugar from a Gatorade or other sweet drink for some quick energy midrace. But for replenishing fluids and electrolytes? Drinking something with salt in it, or pairing a salty snack with water, is just as good—if not better.
Even if you're not exercising for hours at a time, if you know you sweat a lot, water and salt is a good idea. "When sweat losses are high and recovery time is short, it may be better to have a strategy in place to ensure adequate recovery," Maughan says. "This means ensuring adequate intake of both water and salt, and letting the kidneys get rid of the excess. Sports drinks may be a convenient option, but the salt content is generally less than optimal: An Oral Rehydration Solution intended for treating diarrhea in children may be a better option." More realistically, a snack or meal that has some sodium in it should do the trick.
If you're a heavy sweater (or have low blood pressure), Detroyer also recommends adding rich bone broths and soups to your diet, which are both hydrating and rich in sodium. She also suggests healthy, salty snacks, like pickles and olives, as well as fermented foods like kimchi.
When it comes down to it, factors like size, gender, activity level, the weather, how much you sweat, and any medications you're taking can impact how much water and how many electrolytes you actually need. The best advice is to listen to your body. Make sure you feel hydrated before you start exercising, and drink before and during if you're thirsty—don't feel like you have to overload on water, though, if you feel fine. If you're sweating excessively, working out for more than an hour straight, or exercising in really hot and humid temperatures, eat or drink something with sodium to keep your electrolyte levels healthy.
