Wai Gong (外功) or "external skill" is the so called "hard style", "external" or wàijiā (外家) Chinese martial arts. They are characterized by fast and explosive movements and a focus on physical strength and agility. External styles include both the traditional styles focusing on application and fighting. Many of its martial art forms have spectacular aerial techniques. External styles begin with a training focus on muscular power, speed and application, and generally integrate their Qi Gong aspects in advanced training, after their desired "hard" physical level has been reached.