Fluid Facts for Athletes

  • Sweat contains more than just water; it has electrically charged particles that help keep water in the right balance inside and outside of cells.

    Electrolyte Average amount/ 2 lbs (1 liter,~1 quart) sweat Food reference
    Sodium 800 mg (range 200-1,600) 1 quart Gatorade = 440 mg Sodium
    Potassium 200 mg (range 120-600) 1 med banana = 450 mg Potassium
    Calcium 20 mg (range 6-40) 8 oz yogurt = 300 mg Calcium
    Magnesium 10 mg (range 2-18) 2 Tbsp peanut butter = 50 mg Mg
  • Dehydration is more common than overhydration, but overhydration to the point of hyponatremia (low blood sodium) is very dangerous and can escalate into seizures, coma and death. The symptoms (that become increasingly severe), include headache, vomiting, swollen hands and feet, undue fatigue, confusion (due to progressive swelling of water in the brain) and wheezing (due to water in the lungs).

More: Measure Your Sweat Loss for Optimal Hydration

  • In general, hyponatremia that occurs in events that last for less than four hours is from overdrinking water before, during and even after the event. Don't drink more than you sweat; learn your sweat rate!
  • Hyyponatremia that occurs in ultra-endurance events that last for more than four hours is often related to extreme sodium losses. Hence, with extended exercise, be sure to replace sodium losses with more than just sports drinks. (Sports drinks generally contain too little sodium to balance sweat loss.) Choose endurance sports drinks and salty snacks such as pretzels, V-8 juice, soup, olives, salt sprinkled on foods and even salt tablets.
  • You are likely to maintain better hydration if you have easy access to good tasting beverages before, during and after exercise. "Good tasting" means:
    • a cool temperature (most athletes prefer between 60-70° F)
    • a little sodium
    • an appealing flavor. (What makes a flavor "appealing" varies greatly between people, cultures).

More: Stay Hydrated with High Water Content Foods

  • Muscle cramps are believed to be associated with dehydration, electrolyte deficits and muscle fatigue. If you sweat profusely, are left caked with salt and experience cramps, take extra care to drink plenty of sodium-containing fluids while exercising. Because of the high salt content in the standard American diet, you can likely replace sodium losses during meals without sodium supplements. But consuming extra salt on your food if you had high sweat losses can be a smart way to enhance recovery, retain fluid and stimulate thirst.
  • If you like a caffeine-boost pre-exercise to enhance your performance, caffeine--in small doses; (180 mg/day, a 12-oz mug) is unlikely to increase your daily urine output nor cause you to become dehydrated. Enjoy it, if desired!

More: Which Hydrates Better: Water or Sports Drink?

  • Alcohol, on the other hand, does have a diuretic effect, particularly in large amounts. After exercise, consume alcohol only in moderation, if at all, with lots of extra water (plus some carbs to buffer the alcohol and refuel the muscles).
  • When you are exercising hard for more than an one hour (or doing less intense, longer exercise), adding 120 to 240 calories of carbohydrates (30-60 g) per hour to your water can help you perform better. These carbs help maintain normal blood glucose levels so you are able to enjoy sustained energy. Sports drinks are an easy way to get carbs + water; for example, 16 ounces of Gatorade offers 25 g carb; 16 oz, Powerade, 140 cals, 35 g carb.
The Bottom Line

For athletes, the saying "Drink responsibly" holds true for all fluids (alcohol-containing or not). Don't let dehydration--or overhydration--hurt your ability to enjoy exercise and perform at your best.

More: 15 Hydration Facts for Athletes

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Reference
  1. American College of Sports Medicine Position Stand: Exercise and Fluid Replacement. Medicine and Science in Sports and Exercise, 39 (2):377-390, February 2007

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