Forrest Vanderbilt says he played football, soccer and wrestled for McCallie School teams, "but I was much smaller than everyone else so I had to be faster to get out of their way."

The speed and evasive tactics he honed then paid off with a $50,000 prize recently when Mr. Vanderbilt conquered the "world's largest obstacle course" on ABC's reality show, "Wipeout."

In addition to winning, he set a new show record for the fastest qualifying round: 1 minute, 6 seconds. He further notched his name in "Wipeout" fame by becoming only the second contestant in show history to clear the infamous Breakaway Panels (a series of planks over a huge mud pit that fall away from a contestant's path as they are crossed).

Mr. Vanderbilt, McCallie class of 1996, is the son of Dr. and Mrs. Doug Vanderbilt. He now lives in Los Angeles, he said in a telephone interview, where he is a graduate student at UCLA working on his doctorate in science and engineering. He said he also works an internship with the Army Corps of Engineers.

After submitting an e-mail application, Mr. Vanderbilt was one of the 24 contestants chosen to compete on the June 17 episode. The show is taped in Santa Clarita, Calif., where contestants are eliminated in rounds of increasingly difficult obstacle courses. The final four run "The Wipeout Zone," a cringe-inducing course where the best time wins.

"They give you a short summary of different obstacles, but you can't watch the others run the course," Mr. Vanderbilt said.

He didn't have a gameplan, he said, other than "move fast."

Mr. Vanderbilt's speed on the qualifying course has made him a YouTube celebrity with numerous videos of the feat online.

The qualifying round's signature stunt is the "big red balls," giant rubber-like balls on pedestals spaced several feet apart in a water hazard.

"They were tough because you don't know what they'll feel like," he said of maintaining his balance while leaping from one to the next.

In the last run for the money, Wipeout Zone, Mr. Vanderbilt was launched into the air off an aqua slide, climbed uphill against a 1,000-gallon tidal wave, then ran a zigzag across a series of elevated platforms while a moving beam tried to knock him off and water cannons were shooting at him. The exhausted contestant then had to leap across three rotating platforms, and stick the landing on each, beneath an onslaught of water to finish.

Mr. Vanderbilt completed the Wipeout Zone in 5 minutes, 48 seconds.

The former Chattanoogan said he is getting married in December and will put some of his prize winnings to use paying for their honeymoon, as well as paying off student loans.