For all ages, hydration is key! ...the key to making you feel energetic and good in your body when you step on the field or start a work out. Dehydration can cause: sluggishness, change in mood, change in alertness, decrease in blood pressure, increase in difficulty for the heart to pump blood efficiently, and overall decrease in performance.
Hydration doesn't mean pounding a water or gatorade right before the game. Rather, drinking good fluids throughout the day!
Here is a great article that explains how dehydration affects the body. For example, did you know that dehydration can reduce your athletic performance by 7%- 60%? and, if you wait until you feel thirsty to drink you will still be 25-50% dehydrated after you quench your thirst!
Check it out: http://www.livestrong.com/article/531789-dehydration-in-sports-performance/