The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


When Do You Need More Than Plain Water?

Posted in
Eat better

Friday, Jun 18, 2010

If you read Monday's blog you know that high outdoor temperatures and humidity (like we experience here in TX during the summer!) coupled with exercise can lead to extreme dehydration. But, it won't if you make a conscious effort to stay hydrated before, during, and after your physical activity. How do you do this? Here are the fluid recommendations again:

• Start hydrating 4 hours before activity by drinking 2-3 cups (16-24 ounces) of fluid. • If signs of dehydration are present despite this (i.e. not needing to urinate), drink another 1-2 cups (8-16 ounces) 2 hours before activity. • Drink 6-12 ounces every 15-20 minutes of activity. • After activity, drink 3 cups (24 ounces) for each pound lost. 

Elite athletes and weekend warriors alike often believe that the best fluid replacement during exercise is a sports drink. After all, it has sodium and potassium to replace these electrolytes that are lost during exercise, right? While sports drinks do have their time and place, plain water is adequate under many (maybe most) circumstances. 

Choose PLAIN WATER: when your exercise is less than 1 hour and low to moderate in intensity.

Choose a SPORTS DRINK: when your exercise is greater than 1 1/2 hours and moderate intensity OR greater than 1 hour and high intensity OR you are exercising in extreme heat.

What's the advantage of a sports drink?

  • Carbohydrates. A concentration of carbohydrates between 4 and 8 percent provide fuel for the muscles and brain without impairing gastric emptying.
  • Electrolytes. Sodium increases fluid absorption and stimulates thirst, resulting in increased fluid intake. Contrary to popular belief, however, the amount of sodium in most commercial sports drink is low. So, salty foods are still encouraged to replace salt losses after intense exercise/sweating. In other words, sports drinks should be used as a fluid replacement, not an electrolyte replacement.
  • Flavor. The more you enjoy the flavor of a drink, the more you will drink.
What's the disadvantage of a sports drink?
  • Calories. If you follow the lower end of the fluid replacement recommendations and drink 24 ounces before exercise, 18 ounces during exercise, and 24 ounces after exercise that's 66 ounces and over 400 calories from your sport's drink (assuming 50 calories/8 fl ounces)!
  • Cost. The cost of two 32 fl ounce sports drinks could be anywhere from two dollars to four dollars. While that doesn't seem like much, it adds up over time.
So what do you think? Do you see many people (including yourself?) drinking sports drinks when plain water would be recommended? How might you make plain water more palatable if you don't like it's taste?

American College of Sports Medicine; Sawka MN, et al. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc. 39:377-390, 2007.