There's nothing quite like running on a woodland trail. The unpredictability of the terrain sharpens your senses as you leap over roots and puddles and zig-zag through tree branches and fallen logs. The same is true for open-water swimming and mountain biking. There is a raw excitement -- and undeniable sense of danger -- that you can't get from paved roads and chlorinated swimming pools.
With the side-by-side growth of triathlon and outdoor adventure sports, it was only a matter of time before the two worlds collided. In 1996 on the island of Maui, outdoor enthusiasts and endurance racers got together for the first Aquaterra triathlon consisting of an open-water swim, mountain bike ride and trail run. The popularity of that first race resulted in the creation of a whole new breed of competitive off-road racing called XTERRA [source: XTERRA Planet].
The standard XTERRA format is a 1.5-kilometer (0.9-mile) open-water swim, 30-kilometer (18.6-mile) mountain bike ride and an 11-kilometer (6.8-mile) trail run. The laid-back sport has grown into a highly competitive global network of championship races and rankings. There are more than 50 sanctioned races held in the US every year and the International Triathlon Union held the first World Off-Road Championship in 2008.
We're also seeing some creative variations on the off-road format to accommodate more and more outdoor disciplines. One example is the Fever River Triathlon in Illinois, which consists of a six-mile (9.65-kilometer)canoe race, 17-mile (27.4-kilometer)mountain bike section followed by a 5-kilometer (3.1-mile)trail run [source: Fever River Triathlon].