What is a Triathlon?
A triathlon is a multiple-stage competition involving the completion of three continuous and sequential endurance disciplines. While many variations of the sport exist, triathlon, in its most popular form, involves swimming, cycling, and running in immediate succession over various distances. Triathletes compete for fastest overall course completion time, including timed "transitions" between the individual swim, cycle, and run components. The word "triathlon" is of Greek origin from τρεις or trei (three) and αθλος or athlos (contest).
Triathletes in the swim stage must jockey for position, and thus can gain some advantage by drafting, following a competitor closely to swim in their slipstream. Triathletes will often use "dolphin kicking" and diving to make headway against waves and body surfing to use a wave's energy for a bit of speed at the end of the swim stage. Triathletes will often use their legs less vigorously and more carefully than other swimmers, conserving their leg muscles for the cycle and run to follow. A modified stroke allows the triathlete to lift the head above water to sight without interrupting the swim or wasting energy. Many triathletes use altered swim strokes to compensate for turbulent, aerated water and to conserve energy for a long swim. In addition, the majority of triathlons involve open-water (outdoor) swim stages, rather than pools with lane markers. Also, open-water swims necessitate "sighting": raising the head to look for landmarks or buoys that mark the course.
Triathlon cycling can differ from most professional bicycle racing depending on whether drafting is allowed during competition. In some competitions, like those governed by USA Triathlon and the World Triathlon Corporation, drafting is not allowed, and thus the cycling portion more closely resembles individual time trial racing. In other races, such as those in World Cup and Championship racing, drafting and the formation of pelotons are legal. This places an emphasis on running performance as several athletes will enter the bike to run transition at the same time due to drafting.
The primary distinguishing feature of running in a triathlon is that it occurs after the athlete has already been exercising in two other disciplines for an extended period of time, so many muscles are already tired. The effect of switching from cycling to running can be profound; first-time triathletes are often astonished at their muscle weakness, maybe caused by lactate accumulation and the bizarre, sometimes painful sensation in their thighs a few hundred yards into the run, and discover that they run at a much slower pace than they are accustomed to in training. Triathletes train for this phenomenon through transition workouts known as "bricks": back-to-back workouts involving two disciplines, most commonly cycling and running.