Staying hydrated is crucial during exercise to boost performance and reduce fatigue, but it's possible to drink too much water and throw off your body's delicate balance, with major side effects, according to an exercise scientist.
Known as hyponatremia, a lack of electrolytes is rare but can have serious and sometimes life-threatening consequences, said Sean Langan, an associate research director at the University of Connecticut's Korey Stringer Institute
"Hyponatremia is a fancy term for low sodium. It's relatively rare, but it can lead to sudden death in athletes," he told Insider.
The most common scenario for electrolyte issues in otherwise healthy people is when athletes are exercising for a long period of time at a low intensity and drinking plenty of water, but not sweating it out fast enough, Langan said.
When that happens, the body can end up holding on to too much fluid, diluting the levels of the electrolytes sodium, potassium, and chloride.
Normally, your kidneys help get rid of excess water by making you have to pee. But during exercise, blood flow is diverted from the kidneys to the muscles, and too much water can become an issue, according to Langan.
"The idea is that you're drinking fluids with no salt and drinking them faster than you can pee or sweat them out. You dilute your blood," he said.
Runners tackling a marathon or other endurance event for the first time can be particularly susceptible because their pace will be slow, and they'll likely take advantage of water breaks along the way, according to Langan.
To help prevent electrolyte imbalances, athletes can add a sports drink or similar supplement to their hydration during or after training, he said.
"For the regular person, it's really not something you need to be too concerned about. You should consume them but beyond what you're getting in your diet, there's no need to consume anything extra beyond a sports drink or pinch of salt in your water," Langan said.
Electrolytes are important even if you aren't exercising, too. Other potential causes of hyponatremia include excessive alcohol use, certain medications like diuretics, underlying illnesses, or persistent vomiting or diarrhea, which can make it hard to replenish the body's supply of sodium, according to the Mayo Clinic.
You may want to add more salt and other electrolytes to your water if you notice the following symptoms: