All athletes must be aware of the importance of staying well hydrated before, during and after a physical activity. Adequate hydration is a recurring and very effective advise for many different objectives. No wonder if we consider the roles that water plays in our body. Water is involved in all cell reactions, as the reaction medium, as a reactant or product. It also participates in the transport of nutrients, gases and metabolic waste products. As if that were not enough, also it acts as a refrigerant muscle when they are heated during exercise, evaporating sweat, eliminating vapor exhaled air or directly through the skin. Hydrate before exercise has a clear objective: to ensure proper functionality and muscular performance in the first phase of the exercise. It is recommended to take between 400 and 600 ml water, 2 or 3 hours before exercise to allow the renal system regulates the total body fluid volume and achieve the optimal values of osmolarity. During the exercise, our goal is to maintain a positive hydrate electrolyte balance, since a deficit would adversely affect athletic performance. It is recommended between 150 and 350 ml of water every 15 or 20 minutes, from the beginning of the session, to prevent the lowering of sodium. If exercise is intense and long lasting, you should not take only water, add a drink with carbohydrates to keep the oxidation of sugars, normalize hypoglycemia, delaying fatigue and speed recovery of lost glycogen. By the way, the drink should not be too cold but feel like, because at low temperatures the absorption takes place more slowly. Too hot, it has the same problem, so the best thing is a drink that is simply «cool». Rehydrate after exercise is intended to restore muscle physiological functions as soon as possible. Ideally, complete rehydration for the next two hours to complete the exercise. It is recommended that at least 150% of the weight loss cover the loss of fluid through sweat, plus obligatory urine loss. At this stage, carbohydrates should be taken as soon as possible, because the muscles are very receptive to glucose uptake and this will promote muscle glycogen resynthesis. Put a little care, will lead us to adopt healthy habits regarding our hydration while enhancing the results of our efforts with diet and training.