Athletes tackle the running portion of the 2010 Budapest ITU Aquathlon World Championships.

Janos Schmidt/triathlon.org

Are you a competitive athlete who pours everything you have into combining swimming, cycling and running? Some of the most hard-core athletes on Earth find top-notch competition through the International Triathlon Union (ITU), the world governing body for the Olympic sport of triathlon and all related multi-sports. The International Olympic Committee (IOC) and the Association of Summer Olympic International Federations (ASOIF) officially recognize the organization.

The ITU supports the growth of triathlons around the world by working with national and continental federations to develop the sport, from grass roots to the elite performance level. Training, education, event management assistance and organizing world-class events are just a few of the ways in which the ITU helps promote the sport.

A triathlon combines swimming, cycling and running into one event, performed continuously with no breaks. A standard race consists of a 1,500-meter (.93-mile) swim, a 40-kilometer (24.8-mile) bike ride and a 10-kilometer (6.2-mile) run. Triathlons are held around the world, from Alaska to Angola. While terrain and climate may vary, most triathlons follow the same format:

Swim.Triathlons begin with a swim in open water (lakes, rivers, oceans, etc.) or a pool. Swimmers often begin in small groups for added safety, and they may wear wetsuits if the water temperature is too cold.

Transition (T-1). After the swim, athletes transition to their bikes. Each athlete's equipment is placed within a rectangular area that is specially designed so that all participants travel the same distance.

Cycle. The bicycle route is usually mapped out using public roads that are closed to traffic or large parks.

Transition (T-2). Athletes rack their bikes and change from cycling shoes to running shoes.

Run. A 10-kilometer (6.2-mile) run completes the race.

The ITU is also the world governing body for these multi-sports:

Duathlon. This combines running and cycling, usually with a 10-kilometer (6.2-mile) run, 40-kilometer (24.8-mile) cycle and then a 5-kilometer (3.1-mile) run.

Aquathon. A triathlon without cycling, the run-swim-run event may take only 30 minutes to complete at the elite level.

Winter triathlon. Athletes run over snowy, mountainous terrain before switching to mountain biking, then cross-country skiing. Courses are designed so that winners finish in about 80 or 90 minutes.

Team triathlon. National teams of four athletes each complete a triathlon before passing the baton to their teammate. There are both same-sex and coed events.

Paratriathlon. Disabled athletes participate in fair and competitive races among different categories of disability.

Long-distance triathlon. The ultimate test of endurance, long distance triathlons cover more than two or three times the Olympic triathlon distance.

For more information about the history of the ITU, read on.