Back for a fourth time since becoming an Olympic sport, the triathlon is one of the most grueling events at the Summer Games.

Triathlon made its debut as an Olympic sport in 2000 at Sydney, so it's fitting that the Oceanic nations of Australia and New Zealand have done very well in the event.

Since the sport's Olympic debut 12 years ago in Australia, seven of the 18 total medals that have been awarded in triathlon have gone to either an Aussie or a Kiwi. Australia holds the slim overall lead with four medals (1 gold, 2 silver, 1 bronze), while New Zealand has one medal of each kind. Switzerland also has taken home three medals in triathlon

The Olympic triathlon course is the same for both the men and women. It begins with a 1,500-meter swim, continues with a 43-kilometer bike ride and concludes with a 10-kilometer run.

A total of 110 athletes -- 55 men and 55 women -- will compete at the London Games.

The United States has produced only one Olympic medalist in triathlon: Susan Williams' bronze at the 2004 Athens Games. The country's best chance to earn some hardware in triathlon this summer also comes from the women's side.

Gwen Jorgensen and Sarah Groff are expected to be the best bets for the U.S. to earn a triathlon medal. Both Jorgensen and Groff qualified for London after finishing second and seventh, respectively, at the 2011 ITU World Championship Series London event. Laura Bennett also will compete for the U.S.

Hunter Kemper is back for a fourth Olympics for the U.S. after finishing seventh at the 2008 Beijing Games. Manuel Huerta was the only other American man to qualify.

Simon Whitfield headlines the list of Canadian athletes. Along with Kemper he is one of only two men to qualify for all four Olympic triathlons. Whitfield won gold in the inaugural Olympic triathlon in Sydney and earned silver in 2008.

Kyle Jones and Brent McMahon will also compete in the men's event for Canada, while Paula Findlay and Kathy Tremblay qualified for Canada in the women's competition.

The host nation of Great Britain figures to have an excellent chance at winning gold in the event, as brothers Alistair and Jonathan Brownlee are both among the best in the world. Countrywoman Helen Jenkins is also among the best on the women's side.

The event will be staged at Hyde Park, where the women's event is scheduled for Aug. 4 and the men's competition taking place on Aug. 7.