Kendra went on vacation for a week. When she returned home she couldn't run as far as she could before. Which principle of exercise describes this?

This is what i found on google “kinetic energy. energy is transferred from one object to another when a reaction takes place. energy comes in many forms and can be transferred from one object to another as heat, light, or motion, to name a few. this energy would be in the form of motion, with the person lifting the blue ball to a higher level.” i hope this you

One splits the atoms and molecules  the other combines them