Water...

One of the most important, yet often overlooked factors in youth sports is proper hydration.
Being hydrated just like being completely rested before a training session or any other sporting event is one of the major keys to not only performing at the highest level but also to staying healthy and creating long lasting results.

Human body consists of about 60% water, wheres muscles are about 75% water.

Water plays a number of roles in the body, but during exercise its key role is to maintain the right body temperature. Working muscles generate a lot of heat and it must be released into the environment, otherwise the body will overheat. High body temperature causes severe fatigue, and a further increase in temperature is dangerous for the brain, kidneys and liver. It is estimated that under very intense exercise (90% VO2max), body temperature would increase every 4 to 5 minutes - if it wasn't for the appropriate mechanisms to prevent it. That's why we start to sweat so that the heat can dissipate along with the evaporating water.

How to hydrate...

Every day hydration

It is very important to take care of hydration at all times, not only while excerising. For every 1 kcal in the diet there should be 1 ml of water (e.g. 2000 kcal equals 2 liters of water - half a gallon). Counting water intake is difficult, so in everyday conditions it is worth relying on the color of urine. The color of the urine stream should not be darker than that of apple juice. It may or may not be transparent.

Before activity hydration

You should start hydrating about 2-3 hours before the start of your activity, you should drink about 300-500 ml (two cups).  Then, about 20 minutes before exercise, you should drink about 120-180 ml (one cup) of fluid.

During activity hydration

During activity your water intake should be 400-800 ml (2-4 cups) per hour. Fluids taken during activity should contain glucose (supports hydration and is a source of energy) and sodium (supports hydration and prevents the decrease of this element in the blood). Most sports drinks meets these conditions.

Post activity hydration

At the end of activity, you should replenish all the fluids that were lost during exercise. In fact it is recommended to replenish 150% of water we lost. The easiest way to determine how much water we lost is to weigh our self before and after activity.
For every lost pound we should drink about 3 cups of water withing 2-3 hours post activity.