Traditional triathlons are something of a logistical nightmare. The cycling and running portions are easy enough, as long as you can block off several miles of paved roadway for half a day. But what about the swimming portion? You could use a large pool, but how do you fit all the competitors in at once and keep track of how many laps each person has completed? You could use a natural body of water, like a lake, river or ocean, but what if your location is landlocked?
Duathlons solve this problem by getting rid of the swimming portion of the triathlon altogether. There are still three legs to the race, but the order is run, bike and another run. The advantages are two-fold: The course logistics are considerably simpler, plus duathlons are attractive to athletes with relatively weak swimming abilities.
Like traditional triathlons, sanctioned competitive duathlons come in all different lengths. The "international" course calls for a 10-kilometer (6.2-mile) run, 40-kilometer (24.9-mile) bike ride and 5-kilometer (3.1-mile) run, while the "Powerman" course bumps it up to a 10-kilometer (6.2-mile) run, 60-kilometer (37.3-mile) bike ride followed by another 10-kilometer run [source: USA Triathlon].
Duathlon is a fast-growing non-traditional triathlon discipline. In 2008, USA Triathlon sanctioned more than 400 races in 48 states, each race drawing between 50 and 200 participants [source: USA Triathlon]. Next we'll look at a triathlon designed for strong swimmers, the aquathlon.