Before this two-day adventure race ended Monday, no fewer than five people had been sent to the hospital. Two of the casualties were cameramen who weren't even racing. They fell in the line of duty while attempting to document the athletes' kayaking, mountain biking, trekking, running and rappelling down vertical rock faces. I, for one, grew a bit peaked just driving and helicoptering around from checkpoint to checkpoint following the race's arduous progress.

One unstoppable competitor, Bob Damon, 53, a managing director for Spencer Stuart, an executive recruiting firm, completed the majority of the more than 24-hour race with a fractured shoulder. In last year's inaugural race, the Spencer Stuart team was disqualified because one racer became so dehydrated he had to drop out. So even after Damon took a bone-fracturing spill on his mountain bike early in this year's competition, there was no way he was going to give up. "It's all for one and one for all," says the indefatigable musketeer, adding that three days later his shoulder "feels like shit." He's making an appointment with an orthopedic surgeon.

The Presidio Challenge is the Mount Everest of corporate team-building exercises. "It's the new economy golf," explains Cathy Benko from Deloitte Consulting, the corporate sponsor of this year's event. Except that you sweat a lot more during the challenge. And you might die.

But the goal of all this exertion isn't just to test personal limits. It's to learn how you really work with your office mates under pressure -- limb-threatening pressure. If you think that it's hard enough trying to share a communal workplace refrigerator with some of your co-workers, try to picture huddling under a single sleeping bag with two of them after a day of grueling athleticism without a shower. If it's cold enough, before you know it, you'll be "puppy piling" -- blobbing into a mound of flesh for the added warmth of body heat while you catch a few hours of required sleep before hitting the trail again. It's enough to make the traditional "drink till you embarrass yourself" team-building exercise of the company holiday party look like a hootin' good time.

Why would even the most hardcore athlete voluntarily subject herself to such rigors with the same people she has to face around the cubicles every weekday? "We are here to defend the athletic honor of the new economy," says Nate Tyler, team captain for the group from Keen.com. Dustin Sellers, Keen's director of marketing, says that dot-coms have a lot to prove these days: "You can't show your face in the Marina. It used to be pretty hip to be a dot-commer. But as of late, with the market crashes, it's not as hip. We're taking it as a personal challenge to get out there and show that we're not taking this lying down." He pauses, adding: "Our goal is to finish."

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