Approximately 70 percent of your body is water. Muscles are 3/4 water. The blood is 82 percent water. Your brain is 76 percent water. And your lungs are 90 percent water.

Water is needed as a coolant, to digest and absorb food, transport nutrients, build and rebuild cells, remove waste products, and enhance circulation. Losing as little as 2 percent water hurts your jogging/walking performance. Summer joggers/walkers don't give water the respect it deserves. True, it does not provide energy, and it is not an anti-oxidant, but water is involved in just about every process in the human body. Eight glasses of water a day are enough for sedentary couch potatoes, but not for jogging/walking in the mid-day heat. Many are chronically dehydrated. You need about 1 milliliter of water per calorie expended. That means if you burn 2,000 calories, you need an additional 2 liters (2 quarts or 8 cups). Drink extra water before you begin your jog/walk. Four hours before you set foot out of the air conditioning, start drinking 8 ounces of water every 15 minutes. If you drink enough water to support your training, blood-sludgy effects of dehydration will be transformed into super-hydrated speed-walk/jogs.If you are jogging/walking for more than 2 hours, research has demonstrated that carbohydrate sports drinks and juices can enhance your performance. A variety of sports drinks are on the market. Sometimes these drinks are too sugary so I dilute them with water.Look for a sports drink with between 10 and 20 grams of carbohydrates per 8 ounce serving (more carbohydrates than that decreases fluid absorption into the intestines). Meal replacement drinks have additional protein and carbohydrate. Read the label to make sure your drink has equal amounts of potassium and sodium (about 50 milligrams in an 8 ounce serving). And enjoy the taste (you will drink it if you like it).

Other drinks that fit into your jogging/walking program may include water, skim milk (whole milk is 50 percent fat, 2 percent milk gets 36 percent of its calories from fat), limited amounts of diet soda, limited coffee, and limited tea.

Your thirst mechanism may malfunction during intense training. Prime the pump by forcing yourself to sip fluids every half hour. Contrary to the opinions of some health fanatics, it is not mandatory to drink pure water all of the time. Juices are 95 percent water, and oranges 90 percent. Also soups, grapes, and yogurt are mostly water. Coffee and tea are 99 percent water, but the caffeine produces a moderate diuretic effect. Drink enough fluids so that your urine is clear and copious and that you feel a need to relieve yourself every 2 hours.