Commercial sports drinks have increased public awareness about the importance of adequate fluid intake during exercise. People often perceive that active people can’t get enough water— particularly when exercising in the heat. They’re wrong. Drinking too much water is dangerous and can lead to water intoxication (hyponatremia), which can cause brain swelling and death within a few hours. Excess water dilutes the electrolytes (sodium, potassium, chloride, magnesium) in the cells, which destroys the body’s capacity to manage body fluids. The following principles will ensure that you consume the correct amount of water before, during and after exercise:
- Drink when you are thirsty. This will prevent dehydration and excessive water intake.
Coffee, tea and carbonated drinks contribute to hydration, but should not be the primary fluid-replacement beverages.
- Salted fluids help replace lost electrolytes.
- Weigh yourself during workouts: limit weight loss to three percent; weight gains suggest overhydration and water intoxication.
- Take frequent water breaks.
- Don’t drink too much water. Weight increase and swelling (bloating) during practice or competition can mean you are drinking too much. (Clinical Journal Sports Medicine, 25: 303-320, 2015)