Sentence:  It is made up of tumbling , which might be said to start with a somersault , run through such stunts as headstands , <WSD>handstands</WSD> , cartwheels , backbends , and culminate in nearly impossible combinations of aerial flips and twists and apparatus work . 
Meaning of the word marked with <WSD> tags:  the act of supporting yourself by your hands alone in an upside down position