Shadowboxing is a combat sport exercise in which a person throws punches at the air as though there is an opponent, and is commonly used as a warm-up exercise. Practised primarily in striking-based martial arts or sports such as boxing, it serves mainly to develop and refine one's punching technique. Muhammad Ali once performed a now famous shadowboxing routine next to Howard Cosell for ABC's Wide World of Sports television cameras. Black Nova Scotian boxer George Dixon is widely credited for developing the technique.