Chi

Chi are the energy paths flowing around in a Bender's body. As Iroh showed in Bitter Work, chi can be felt swirling around inside one's body, and the path can be changed to allow energy to flow in certain directions, useful when using Lightning redirection. Ty Lee can block someone's chi by hitting them in several pressure points around the benders's body. Ty Lee used this in The Drill to take down some of the Earth Kingdom's toughest Earthbenders.