to certain degrees. Contact between players is often classed by different grades ranging from non-contact, where there is no contact between players, to full-contact or collision sports, where the rules allow for significant physical contact. Equipment As a result of the risk of injury, some sports require the use of protective equipment, for example American football protective equipment or the gloves and helmets needed for underwater hockey. Some sports are also played on soft ground and have padding on physical obstacles, such as goal posts. Most contact sports require any male players to wear an Abdominal Guard to protect their male genitalia. The cost of equipment can be an obstacle to participating in many sports. Grades Full-contact A (full) contact sport is any sport for which significant physical impact force on players, either deliberate or incidental, is allowed or within the rules of the game. Contact actions include tackling and blocking and a whole range of other moves that can differ substantially in their rules and degree of application. Examples of full-contact sports include American football, Canadian football, Australian rules football, rugby union, rugby league, rugby sevens, ice hockey, lacrosse, hurling, arena football, futsal, underwater football, water polo, slamball, roller derby, kabaddi, quidditch, shinty and wheelchair rugby. Full-contact martial arts include Boxing, Mixed martial arts, Sambo, Sumo, Wrestling, Muay Thai, Brazilian jiu-jitsu, Judo, Sanshou, Historical European Martial Arts, Lethwei, Taekkyon, Vovinam, Pradal serey, Savate, various forms of full contact karate, and some forms of Taekwondo Semi-contact A semi-contact sport is typically a combat sport involving striking and containing physical contact between the combatants simulating full-power techniques. The techniques are restricted to limited power, and rendering the opponent unconscious is forbidden. Some semi-contact sports use a point system to determine the winner and use extensive protective gear to protect the athletes from injury. Examples of semi-contact sports include karate, kickboxing, kalaripayattu, Kenpo, various Korean martial arts that incorporate contact rules sparring, kendo, some types of historical European martial arts, fencing and taekwondo. Another indicator of a semi-contact martial arts competition system is that after a point is rewarded the adversaries will be separated and resume the match from safe distance, but often it is possible to argue if some martial arts sports belong in one contact group or another. Tagging-only In some sports, the only or main type of physical contact allowed is tagging (touching an opponent lightly, usually with a