Keep your tank full.

With hot weather upon us, your body's demand for fluids increases. Don't forget to increase your water intake as the temperature rises. We've said it before (see Running & FitNews, September 1998) and we'll say it again: it's easier than you think to get dehydrated, especially if you're running in hot weather. Drink before, during and after exercise.

Know the warning signs that tell you you're running low. Susan Kleiner, Ph.D., R.D., lists the following early signs of heat stress and dehydration in her book, Power Eating (1998, Human Kinetics Publishers, Inc., Champaign, IL): fatigue, loss of appetite, flushed skin, heat intolerance, light-headedness, dark urine with strong odor, and dry cough.

What about feeling thristy? Thrist is an unreliable indicator of your need for fluids. You won't feel thirsty until you are already low, when you've lost about 2% of your body weight in fluids. Even the act of drinking can turn off your "thirst" indicator before you're fully rehydrated.

Runners especially need to think of water the same way you think about food and training. Eating right and training right takes planning. Plan for your water needs in the same way. Drink eight to 16 ounces before your workout, five to 10 ounces every 15 to 20 minutes during, and at least 16 ounces afterwards. That should be pretty good insurance against dehydration.

When should you choose a sports drink over water? When you will work Out longer than 45 minutes In one study, l6 young men and women were given either Placebo flavored water or Gatorade and then asked to cycle in intense one-minute bursts followed by three-minute rests, over and over until they were exhausted The water group could perform less than an hour while the Gatorade group went for nearly 90 minutes. Researchers continue to provide evidence for choosing a sports drink if you want an optimal workout. (International J of Sports Nutrition, 1997, Vol. 7, PP. 261 -2 73)