How much water is lost during exercise?

During high-intensity exercise, a person can lose up to 2.0 liters of water per hour! However, 1.0 liter of water per hour is more common. Sweat rate can vary depending on the environmental temperature, humidity, type of clothing worn during exercise, intensity of exercise, fitness level of the individual and acclimation of the individual to the environment. Replacing fluids during and after exercise is very important for staying hydrated and preventing dehydration. Signs of dehydration include dark colored urine (urine should be the color of water with a splash of lemon), muscle cramps, decreased sweat rate, and increased fatigue.