Lack of water can lead to dehydration, a condition that occurs when you don't have enough water in your body to carry on normal functions. Even mild dehydration - as little as a 1 to 2 % loss of your body weight - can sap your energy, making you tired. Dehydration poses a particular health risk for the very young and the very old. Signs and symptoms of dehydration include:
EXCESSIVE THIRST LITTLE OR NO URINATION
FATIGUE MUSCLE WEAKNESS
DRY MOUTH LIGHTHEADEDNESS
As the summer months approach maintaining adequate hydration moves to the top of the priority list for those who exercise. Dehydration and even being under-hydrated at the start of exercise can negatively impact performance. Hydration during prolonged exercise is even more challenging since fluid intake often fails to match sweat losses. If you're healthy and not in any dehydrating conditions, you can generally use your thirst as an indicator of when to drink water. But thirst isn't always an adequate gauge of your body's need for fluid replenishment. The older you are, the less you are able to sense that you're thirsty. And during vigorous exercise, an important amount of your fluid reserves may be lost before you even feel thirsty. So make sure that you're sufficiently hydrated before, during and after exercise.
It is important that you consume plenty of fluid BEFORE exercise in order to be adequately hydrated when you start to exercise and to help prevent dehydration during exercise. This can be accomplished by remembering to drink fluids throughout the day, then hydrating 2 to 3 hours before exercise with 16 ounces (2 cups) of fluid, and again 10 to 20 minutes before exercise with 8 ounces (1 cup) of fluid. During exercise, you should drink 8 to 12 ounces of fluid every 15 to 20 minutes. The goal of fluid replacement is to replace 100% of sweat lost during exercise.
Drink plenty of water on a daily basis to help maintain general health and hydration. Water is a refreshing, calorie-free beverage option for those trying to manage their body weight. For the serious athlete, water may not be the best source of re-hydration because unless water is consumed with food, it cannot replace the electrolytes (mainly sodium and potassium) that are also lost in sweat. The average person exercising 30-60 minutes at a moderate level of activity most likely can be re-hydrated with water and foods such as oranges or bananas to replenish potassium stores.
Energy drinks that contain herbs, amino acids, protein, and other substances, usually contain them in such small amounts that they are unlikely to have any noticeable effect (positive or negative) on athletic performance. However, they may contribute to the inefficient absorption of fluid and nutrients from the intestine, leading to gastrointestinal distress, which may impair performance. In an effort to stay hydrated, it is wise to limit or avoid caffeine- and alcohol containing beverages, as these substances have a dehydrating effect on the body.