Frank Dux is a real martial artist

As a teenager, Frank Dux and friends of the same age break into the Tanakas' house. Surprised by the returning family, the boys flee, except for Frank. When Tanaka realizes Frank's inner potential, he offers his father to help with his son's martial arts training. Tanaka's son becomes a friend of Frank, but dies as a young man. Frank now asks Tanaka, in honor of his son, to train him further. Tanaka agrees and teaches Frank his martial arts. Then Frank goes to the army, where he becomes a highly decorated soldier.
Frank had promised his sensei that he would win the Kumite, a secret full contact championship. In order to honor his venerable master, Frank would now like to take part in the secret Kumite fights in Hong Kong. This competition is unofficial as it is not uncommon for fighters to die. The Army learns of his participation in this competition and puts him under arrest. Frank secretly travels to Hong Kong, followed by two agents who are supposed to bring him back.
In Hong Kong, Frank befriends boxer Ray Jackson, who also takes part in Kumite, and reporter Janice, with whom he starts an affair. At Kumite, however, the great champion Chong Li is waiting, who unfairly injured Jackson in a fight. Dux swears revenge, which he gets in the final fight against Chong Li. Despite unfair tricks by Chong Li, Dux finally wins the fight and then returns to the United States with the two agents, leaving Janice and Jackson in Hong Kong.

Bloodsport is based on the supposedly true story of the American fighter Frank W. Dux. The truth of Dux's statements is, however, very controversial: To this day, he has not been able to provide any evidence that the kumite depicted in the film ever existed in a similar form. This does not detract from the success of the film, because despite its age it is still considered one of the most famous martial arts films of all. However, it almost overtook the fate of many other low-budget productions and it would have gathered dust in the film distribution warehouse, because it was initially cut so "miserable" (quote from Jean-Claude van Damme) that it was not expected to be successful when it was released . It was only on Van Damme's personal initiative that the film was re-cut, partly by himself, especially with regard to the fight scenes; he also added material that had previously been removed from the original version. This enabled him to be seen in the fight scenes more often than DiSalle actually intended and the fights visually increased significantly in hardness, speed and drama. In addition, van Damme provided a new recording of the music. Newt Arnold and Sheldon Lettich wanted to object to the release of the new cut version, but DiSalle recognized the potential of the now fundamentally restructured film. The success proved him and van Damme right: Bloodsport eventually became one of the most successful martial arts films in the world and one of the most successful films in the history of Cannon Films; he has grossed over $ 12 million in the United States alone. There is no longer a copy of the original version, as the original film rolls were used for the editing.
The real Frank W. Dux was responsible for the stunts and the fight choreography in the film, as well as for the training and preparation of van Damme. Incidentally, Frank Dux's records listed in the trailer were able to be proven by him. Among other things, the fastest knockout. Bolo Yeung, who played the role of Chong Li, was 42 years old when the film was made. He later played alongside van Damme in other films.
There is a defused FSK-16 version of the film. Not only are fight scenes classified as too brutal missing in this one, parts of the framework and the training also fell victim to the cut.
In the English version, Frank's surname Dux is pronounced phonetically according to the French spelling Düx (based on his French film background). In the German version it is incorrectly pronounced Dax.
The scenes in the narrow streets of Hong Kong were filmed in the Hak Nam slum settlement, which was demolished five years later (1993)