Sprint Up a Skyscraper
Credit: Jeff Zelevansky / Reuters

Tower running is a niche sport that will break a triathlete. It began at the Empire State Building in 1978 and has spread to 200 staircase races in 40 countries. "It's the most painful race you'll ever do," says competitive stair climber Rickey Gates. "There is no other sport where you max out your heart and lungs so fast."

The sport's showcase event is the Empire State Building Run-Up, held each February – 86 stories and 1,576 steps of vertical pain. The biggest challenge, after elbowing your way through a 36-inch-wide doorway, is the air. "It's stale, dry, and dusty," says Gates, who has run the race four times, coming in second and third. "By the fourth floor, it feels like needles in your lungs." From there, it's a full-bore quad effort, well suited to cyclists, speed skaters, and cross-country skiers. Unlike a track sprint where you can see a finish line ahead, this is mentally grueling: The stairs are endless, turning monotonously upward. This year's champ, Thorbjorn Ludvigsen, a 25-year-old Norwegian construction worker, did it in 10 minutes, 6 seconds.

Or try these:
There are about 100 tower races in the U.S. each year, according to the USA Stair Climbing Association (stairsport.com). Here are two of the most popular:

Scale The Strat
Each March about 600 runners compete in the U.S. Stair Climb Championship, ascending 108 floors – 1,455 steps – at the Stratosphere Casino, Hotel & Tower in Las Vegas. The record: 7 minutes, 5 seconds. [scalethestrat.com]

The Skyrise Chicago
Before One World Trade went up, Chicago's Willis Tower (a.k.a. the Sears Tower) was the nation's tallest. Every November, 2,000-plus race up its 103 flights and 2,109 steps. The record: 13 minutes, 3 seconds. [ric.convio.net]