Water is the main component that keeps the volume of the blood in the body.
DEHYDRATION AND HYDRATION: Because of the vital roles of water in the body functioning, keeping the fluid level of the body is important for athletes who exercise or practice for long hours. A workout under the duration of thirty minutes can get on with water only, but beyond that water loss from the body will lead to dehydration. For athletes probably the most important nutritional concern is fluid replacement. The main loss of water from the body is due to perspiration. In water sports like swimming, one will not even know the loss of water through perspiration as perspiration is rather invisible here. According to various studies if one loses water up to two or more percent of ones body weight ( water makes 60% of the body weight) due to sweating ( If the athlete weigh 50 Kilograms and if he loses one litre sweat ) , that will lead to a drop in blood volume. This will force the heart to work harder to pump the blood through the arteries. This is the extreme situation of dehydration. This leads to muscle cramps. The functioning of the brain heavily depends on water as pointed out by K.G styles, the hydration technique expert (http://EzineArticles.com/ ), and thus dehydration affects the brain leading to fatigue and dizziness. If not rehydrated immediately this situation may even lead to heat illnesses like Heat Stroke and Heat Exhaustion. In addition to excessive sweating, other causes of dehydration are inadequate fluid intake, failure to replace fluid losses during and after the exercises, working out in dry hot weather, in the open, and drinking only when one is thirsty.
The percentage of lose of water from the body and their physiological effects are described by medical scientists like this:
% of body weight lost as sweat --------------------- physiological effect
According to, Ron.j. Maughan and Robert Murray, though we usually take care of the dehydration due to sweat lose during exercises, not much scientific interest is shown to study the pre exercise dehydration. Pre exercise dehydration may be due to passive exposure to heat or by diuretic treatment. In their book "Sports Drinks" they state: "individuals who begin exercise with fluid deficit will not perform as well as they will when fully hydrated." (Ron.j. Maughan and Robert Murray-15). Drinking plenty of fluids before, during and after a workout or race, is the best method to prevent loses of body fluids and dehydration.
Sports Medicine Advisor 2005:4, (www.med.umich.edu/1libr/1libr)) recommends two methods to monitor the hydration. One method is to weigh oneself before practice and after practice. To rehydrate the body, one will have to drink two cups of fluids for every single pound lost during the workout. By checking the colour of the urine too one can