Kung fu, (also known as wushu or martial arts) is one of the most well known examples of traditional Chinese culture. It is probably one of the earliest and longest lasting sports which utilize both brawn and brain. The theory of Kung Fu is based upon classical Chinese philosophy. Over its long history it has developed as a unique combination of exercise, practical self-defense, self-discipline and art. In sports like track and field, ball sports, weightlifting, and boxing, an athlete typically has to retire from full participation in his 30s. Injuries sustained during years of active sport participation at a young age can that affect our health in later life. In Chinese Kung fu, however, a distinction is made between "external" and "internal" kung fu. It is said that "In external kung fu, you exercise your tendons, bones, and skin; in internal kung fu, you train your spirit your qi, and your mind."