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Dehydration and Exercise

Dehydration is a risk when exercising. Many people do not consume enough fluids when they exercise to balance the loss from sweating. Here are some guidelines for avoiding dehydration.

  • Drink extra water before and after exercise. You will also want to drink during exercise, especially if you exercise for longer periods of time. Drink more than normal if the weather is hot, and make sure to drink even when it's cold.
  • After exercise, drink enough water to quench your thirst.
  • Before, during, and after exercise, avoid beverages containing alcohol.
  • There is no need to take a potassium or salt supplement. It is hard to lose too much potassium or salt through sweating.

Some people prefer to use a commercial sports drink to prevent dehydration. These drinks contain salt, potassium, and carbohydrates to replace what you lose as you sweat. Use whichever liquid (water or a sports drink) you prefer. You can make a drink similar to a sports drink by adding 1 tsp (5 g) of salt to 1 gallon of lemonade. Unless you exercise for extended periods, water is probably all you need.

The risk of dehydration is greatest when you are exercising in heat and high humidity. If you regularly exercise in high heat or humidity, your body will gradually get used to those conditions, but at very high temperatures, anyone is at risk for heat-related problems such as dehydration, heat exhaustion, and heatstroke.

Note to endurance athletes: If you are a distance runner or triathlete, there is a chance you could overhydrate—get too much fluid in your body—during your training or event. Overhydration (hyponatremia) can be caused by exercising over a very long period of time, especially in hot or humid weather, and drinking too much fluid. It can cause symptoms such as feeling bloated, sick to your stomach, and confused. Although it is rare, overhydration is a medical emergency when it happens. An athletic trainer or sports nutritionist can help you learn ways to avoid overhydration.

By Healthwise Staff
Adam Husney, MD - Family Medicine
Last Revised June 3, 2013

Last Revised: June 3, 2013

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