Studies on rowers and other athletes have demonstrated that consumption of a carbohydrate and electrolyte beverage is preferable to water. Water has the negative effect of lowering the plasma volume, which limits delivery of fluids to sweat glands and inhibits cooling. The lower plasma volume reduces delivery of needed nutrients to working muscles and removal of metabolic waste products from these muscles. Water also does nothing to maintain blood glucose, which is the primary fuel for the brain and an important fuel source for working muscles. A failure to maintain blood glucose leads to mental fatigue, which results in muscular fatigue regardless of the available fuel in working muscles. It is important for rowers to sip on sports beverages frequently before and during practice and not wait for thirst to occur before initiating drinking (British Rowing, 2018). 

For rehydration the athlete needs to drink fluids immediately after the competition or training. Even in freezing weather, prolonged training sessions on the water result in large sweat losses, especially when done twice daily.  The goal is to sip on something whenever there is a training break, or you can use a camel-back and take frequent sips during the exercise. Sports drinks are the suggested fluid choice for extended sessions, demanding training cycles, or hot conditions since they contain carbs and electrolytes in addition to fluid. If the athlete lost weight it reflects the fluid loss (Lee et al. 2017). Therefore, one should intake 1.5 times the amount of weight loss (Castro-Sepulveda et al. 2014). Intake of 1.5 times the amount of weight loss is effective in enhancing and maintaining hydration status, compared to the previous recommended multiplication factor of 1.  Our athlete lost 0.8kg of her body mass therefore she needs additional  1.2 L of water added to her RDI which is 2 L.