Nowadays, the competitiveness to reach an optimal sport performance, makes that several sportsmen as coaches start the incessant search of aids in nutrition, sport implementation, nutritional supplements and more. Without getting determining factors, in each of them, but they are the final percentage as a whole what would allow to reach the optimal sports performance, due to this we will make reference to a point very neglected by the sportsmen and trainers, probably because they do not have clear knowledge about these, because each sportsman is a world; being the "hydration" an indispensable point, but forgotten. In this document we will try to unveil more accessible parameters, minimising the taboos or tips, meaningless until now maintained; for mountain races it can also provide a very necessary contribution for endurance and adventure sports.