Fluids that have simply entered the body through the mouth cannot be said to have truly been absorbed. It is only when fluids are absorbed through the gut into the bloodstream that they can truly be considered to have been absorbed into the body.

The rate of fluid absorption is influenced by the two factors below. Drinks that allow for quick absorption in both cases are considered suitable for rehydration during exercise.

Recent studies have reported that the type of carbohydrates found in drinks used for fluid replacement during exercise is also an important factor. According to this study, if the two carbohydrates glucose and fructose are contained in a drink, fluids are absorbed into the body quickly. Beverages containing only fructose offer less effective fluid absorption than drinking pure water. Drinks containing glucose and fructose, or table sugar (glucose + fructose), can be considered ideal when exercising. We recommend checking the type of carbohydrates contained in drinks, which are listed on the ingredients label.

Ion supply drinks (sports drinks) can sometimes be seen being drunk diluted during sports activities. How does this change their effectiveness with regards to rehydration? This study took a particular ion supply drink and, without changing the concentration of electrolytes (ions) such as sodium found in the drink, compared results for the drink with half the amount of carbohydrates, and another with zero carbohydrates. It found that the recovery of plasma volume and concentration (amount) of carbohydrates after dehydration are dependent on the concentration of carbohydrates in the beverage. By discovering that rehydration becomes less effective when ion supply drinks are diluted, the study revealed that the carbohydrate content of ion supply drinks is important for the recovery and maintenance of fluids in the body.