As an essentially closed system, the body needs to be as efficient as possible. Hence, once nutrients are delivered throughout the body, waste is subsequently collected and transported out. The relationship that water, as well as sodium, has with the kidneys is what dictates this system. Once the blood collects carbon dioxide from the respiratory process along with metabolic waste from muscular activity, it is all filtered through the kidneys and then excreted via urine. This is where the body maintains proper electrolyte balance and blood pressure to effectively regulate and sustain physical activity.
As important as all of this is, nothing exists in a vacuum. Without a proper cooling system the body will not be able to maintain these other functions. When exercising, the body releases heat by expanding blood vessels close to the surface of the skin. This results in more blood flow, regulated by blood pressure, and more heat is dissipated from the body and into the air with the help of the cooling effect from sweat. Without this internal cooling liquid, the body stays hotter because it takes a higher ambient temperature to trigger the dilation of blood vessels.
The ability for an athlete to mitigate this once it happens goes well beyond being on a training run or racecourse, as anyone who has found themselves in the medical tent with an I.V. can attest to. Studies have found that as little as a two percent loss of body weight through sweating creates a drop in blood volume, which creates more effort by the heart to circulate blood.
Like nutrition, hydration needs to be trained and well planned and not everyone should prescribe to the same methods. In general, an individual should consume around eight cups of water per day, provided his or her diet contains the necessary minerals and nutrients the body needs for optimal functioning. USA Track & Field, along with the American College of Sports Medicine, suggests drinking 17-20 ounces of water or sports drink 2-3 hrs prior to running, 10-12 ounces 15 minutes before, and then 3-6 ounces every 20 minutes. It ultimately depends on personal trial and error. I begin my hydration 30 minutes prior to running and drink 4-8 ounces every 15-20 minutes with supplemental electrolytes.
Hydration is the system by which water enters the body. Dehydration is what happens without it. The next time you take a sip, remember its more than just water you are drinking. It’s life!