Today’s Wonder of the Day was inspired by Tyler. Tyler Wonders, “How many legs are in the Iron Man?” Thanks for WONDERing with us, Tyler!

Do you love to swim? How about riding a bike? Does running put you in a good mood? Have you ever combined all three activities into one long, grueling race? If you have, then you know all about the triathlon.

If you've never heard of a triathlon, the "tri" in the name probably gave away the fact that it involves three activities: swimming, cycling, and running. Competitors race in a specific order — swim, bike, run — as one continuous event without resting.

The roots of the triathlon date back to the 1920s in France when a race called "Les trois sports" (literally, "the three sports") challenged competitors to swim across the channel Marne, ride a bike for 12 kilometers, and run for three kilometers. The American triathlon has a more recent history.

The modern triathlon got its start in Southern California when the first Mission Bay Triathlon was held on September 25, 1974, in San Diego. On that day, almost 50 people competed in a race consisting of a 500-yard swim, a five-mile bike ride, and a six-mile run.

Triathlons slowly began to become more popular as other locations hosted their own events. Things really took off in 1978, though, when three popular endurance events in Hawaii were combined to create the Hawaii Ironman Triathlon.

The Ironman, as it has become known, was based upon the Waikiki Rough Water Swim (2.4 miles), the Oahu Bike Race (112 miles), and the Honolulu Marathon (26.2 miles). The first Ironman featured 15 competitors and only 12 finished the race. ABC's Wide World of Sports began broadcasting the Ironman in 1982. By 2006, the event drew nearly 3,000 competitors.

The triathlon achieved Olympic status in 1989 (the fastest any sport has done so), and debuted at the Sydney Olympics in Australia in 2000. The Olympic triathlon consists of a 0.93-mile (1.5-kilometer) swim, a 24.8-mile (40-kilometer) bike ride, and a 6.2-mile (10-kilometer) run.

If you're not up for an Olympic or Ironman triathlon, don't worry. Triathlons come in varying lengths. For beginners, mini or "sprint" triathlons consist of a half-mile swim, 15-mile bike ride, and a three-mile run.

Some event organizers have even come up with interesting triathlon variations to appeal to a wider group of athletes. For example, aquathons feature swimming and running. Duathlons get rid of the swimming in favor of a run/bike/run race. Mountainous areas might even feature races consisting of a combination of trail running, mountain biking, and cross-country skiing.

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