In the red, rocky desert of southern Utah, the air is dry and still and temperatures hover around 100 degrees under the hot summer sun. Not the ideal conditions for being active outdoors-but, then again, Primal Quest, the world's premier adventure race, is not your average outdoor activity.

For starters, the race lasts a grueling 10 days (24 hours each), carrying racers over 400 miles of some of the world's most extreme conditions - including long stretches of desolate plains, high mountains, and whitewater rapids. And competitors don't just run. They do it all: bike, ride horseback, kayak, and rock climb, all the while navigating with a compass and their teammates in an all-out effort to reach each of the race's 42 checkpoints before any other team.

This summer, 89 teams of adventure racers migrated to rural Moab for the event. Some signed up and competed for their share of the $250,000 cash purse - others for the kind of intense challenge you can't get from any other sport.

And as if racing weren't hard enough, building a team with the skills and qualifications needed to win is a whole other challenge. "After training, the chemistry of the team is essential," says John Moss, 36, member of Team Silly Rabbits, who competed in this year's race with Jason Quinn, 32, an emergency-room doctor from San Francisco, and Jennifer Ratay, 31, an endurance mountain-bike champ who spends her days working at Stanford Business School. "It's like having three girlfriends," 35-year-old Rick Baraff, the fourth Silly Rabbit, adds. "We train together year-round. And after it's over we may take off the tights and cape and go back to the normal world - but we're always plotting for the next race."

Like any competition, Primal Quest is as much about preparation as it is about fitness and skill. Before the event, teams pack the provisions they'll need to complete the race: mountain-bike equipment, gear for fixed - rope climbing and mountaineering, as well as gear for paddling and swimming. Food boxes are stuffed with bars, gels, and pills to keep athletes fueled along the way, plus a few supplies you might not expect elite athletes to carry.