Fluid replacement is probably the most important nutritional concern for athletes. Approximately 60% of your body weight is water. As you exercise, fluid is lost through your skin as sweat and through your lungs when you breathe. If this fluid is not replaced at regular intervals during exercise, you can become dehydrated.

When you are dehydrated, you have a smaller volume of blood circulating through your body. Consequently, the amount of blood your heart pumps with each beat decreases and your exercising muscles do not receive enough oxygen from your blood. Soon exhaustion sets in and your athletic performance suffers.

If you have lost as little as 2% of your body weight due to dehydration, it can adversely affect your athletic performance. For example, if you are a 150-pound athlete and you lose 3 pounds during a workout, your performance will start to suffer unless you replace the fluid you have lost. Proper fluid replacement is the key to preventing dehydration and reducing the risk of heat injury during training and competition.