Most weight trainers and exercise enthusiasts underestimate the importance of hydration. You can窶t live a week without staying hydrated. Water helps to regulate temperature, protects/buffers vital internal organs and is useful to our digestive system. It is in well over half of our bodily tissue. Muscles are composed of 75% of it. The Institute of Medicine says that Americans get approximately 80% of their daily hydration requirements from water intake and other beverages and approximately 20% from food sources.