Triathlon is one of the most challenging endurance competitions in sports. The triathlon consists of three segments, normally conducted without a break. The segments of a typical triathlon, in order, are a 1.5-kilometer (0.9-mile) swim, a 40-kilometer (25-mile) bicycle race, and a 10-kilometer (6.2-mile) run.
As an organized sport, the triathlon began in the mid-1970’s in San Diego. Members of the San Diego Track Club began adding swimming and cycling to their workouts to supplement their training runs. Soon, organized swim-bike-run events were being held at Mission Bay in San Diego. In 1978, a group of United States servicemen stationed in Hawaii created the Ironman, the forerunner of the triathlon. It consisted of an ocean swim, followed by a long bike race and run. The present distances for the triathlon segments were established in 1981.
