triathlon

Triathlon is a multisport endurance sport in which athletes swim, cycle, and run in succession, with brief transitions between disciplines. The usual order is swim, then bike, then run. Races range from short formats to long-distance events and can take place on looped or point-to-point courses, with conditions that test endurance, pacing, and race strategy.

Triathlon originated in the 1970s in Southern California, with the first widely recognized modern event held in 1974 in San Diego. The sport has grown internationally under World Triathlon (formerly the International Triathlon Union) and is part of the Olympic program since 2000. The Olympics feature a standard distance triathlon, and the sport also includes a mixed relay event that debuted at Tokyo 2020.

Races are offered in multiple formats. The Olympic distance is 1.5 km swim, 40 km bike, 10 km run. Sprint events are shorter, commonly around 750 m swim, 20 km bike, 5 km run. Long-distance formats include the Half Ironman (70.3): 1.9 km swim, 90 km bike, 21.1 km run, and the full Ironman: 3.8 km swim, 180.2 km bike, 42.2 km run. There are also various regional circuits and time-limited events.

Competitors complete the three disciplines within a single race, moving between disciplines via transitions. Equipment typically includes a trisuit, bicycle, helmet, and running shoes; wetsuits may be used in cold water. Rules vary by sanctioning body, with some circuits allowing drafting on the bike and others prohibiting it. Training emphasizes endurance across disciplines, including brick workouts that couple cycling and running.

Triathlon is practiced worldwide at amateur and elite levels, with major events such as the World Triathlon Championship Series and Ironman races, highlighting disciplined training, nutrition, pacing, and safety.