The higher you are from the ground the more potentional energy you have, the faster you're falling the more kinetic energy you have, but add it up and youll always have the same amount of internal energy. This is pretty much a basic concept of gymnastics. When practicing, the higher the beam is the more potential energy you have, but this also means the harder the fall or the better the dismount when transfered to kinetic energy. Or you could have the beam lower and have less potential energy, the less the fall will hurt but the more difficult the dismount. Youll hope that if the beam is low youll have more power because you have less time to do what you need to do before your feet (or other body part not of choice) hits the ground.