Tai Chi, Tui Shou and Qi Gong are 3 types of martial arts that focuses on inner body development. Inner body development consists of cultivating bones, blood flow, muscles and body fluids. All of these are what traditional chinese refer to as Qi (气). When Qi flows, the body will be able to operate at optimum thus prevent fatiguness, illness or chances of injury. The following clip is Yang style tai ji boxing by Zheng Man Qing.