One of the reasons for the use of surplus energy is to burn off excess energy. After this energy is burned off the body and brain is renewed hence the child is ready to participate in learning activities that you have prepared for he/ she to do.
Children during play uses and require a lot of energy. Therefore I would have to agree with the theory.
A simple demonstration of children using surplus energy can be seen every day without realizing how important it is for children to play.
Discuss the stance you have taken with relevant examples and reasons.
Look how alert a child is after recess, this happens because the child got the chance to socialize with his peers and play for a while, children appreciate any chance that is given to play.
When children have fun, they are happier and happier children are better learners
Children view recess as a time for them to develop and maintain friendship, they use this time to build lasting relationship hence best friend comes about and so they are always dying for recess to tell what has happen at home the night before or what gift they receive. This is a form of surplus energy. This helps the child to relax take their mind off class activity.
If you had to study all day, it would get boring and your study would be fairly unproductive. You must have a break to refresh your mind and eat something. This concept is similar to why preschoolers need to play. The delight and pleasure in play enhances their physical and intellectual development. The best way to keep a child happy and learning is to let him/her play.