An isotonic drink is a type of beverage designed to quickly replenish fluids and electrolytes lost during physical activity. These drinks typically contain a balanced concentration of carbohydrates and salts, making them effective for hydration and energy replenishment. Athletes often use isotonic drinks to maintain performance during prolonged exercise. Isotonic drinks are different from hypertonic and hypotonic drinks, which have higher or lower concentrations of solutes, respectively. Popular brands of isotonic drinks include Gatorade and Powerade, which are commonly found in sports settings. These beverages are especially beneficial for endurance sports, such as marathons and triathlons.