Dehydration (hypohydration) is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism. Isotonic drink is a sports drink designed to help athletes rehydrate when fluids are depleted after training or competition. Electrolyte replacement promotes proper rehydration, which is important in delaying the onset of fatigue during exercise. As the primary fuel utilized by exercising muscle, carbohydrates are important in maintaining exercise and sport performance. The rate of water diffusion is the same in both direction that cell will neither gain nor lose water.