Basic Recommendations for Nutrition and Hydration
To maximize the effectiveness of your training you should consider the following points:

Athletes should hydrate well throughout the day before training or competing
Urine should look like lemonade not apple juice. This is amusing, but true! Water is best. If you are very active during the day, have a supplement drink (such as Gatorade) or fruit juice to replace the electrolytes lost during exercise. Soda is not recommended, but is better than nothing at all!

Athletes should eat healthily and in good time before training and competition
It is important to plan ahead so that you have plenty of time to digest food before you train (at least two hours). A mixture of carbohydrate and protein is best and will last a long time. If time is short, (less than two hours) stick with a light carbohydrate snack - fruit, especially bananas, a cereal or sports nutrition bar.  It is not wise to train if you have not had food or fluids for four or more hours. 

Drink plenty of fluids including supplement drinks, during training 
Large amounts of body weight can be lost through exercise. Most of this loss is through sweating. If this loss is not replaced by fluids, performance initially is significantly diminished. Ultimately it can lead to muscle cramps, nausea and heat exhaustion. Supplemental drinks (Gatorade, Powerade or, fruit juice with a little salt added) are recommended to replace the loss of salt and potassium, and other electrolytes.

Eat well after exercise and make sure they have plenty of sleep.
It is very important that you eat healthily and as soon as possible after exercise. For muscle repair and recovery, protein is essential.