Crazy new sport - running up skysrapers!

The agonies people are prepared to inflict upon themselves in the name of fitness and fun are often baffling, but "tower running" takes endurance to a whole new dimension. It is a sport of few rules: you run up a skyscraper's stairwell, you collapse and the fastest time wins. Despite the fact that it sounds about as enjoyable as gargling with magma, it is one of the fastest-growing sports in the world. In America, there are countless competitions, with the three majors being the US Bank Tower in LA, the Sears Tower in Chicago and the Empire State Building in New York. There are races, too, all over Europe, Asia and South America, though none yet of any significance in Britain.

The elite athletes who pioneer this new craze are, unsurpisingly, a rum bunch. There's 55-year-old Kurt Hess, who holds the world record for altitude climbed in 24 hours (30,000m) and who trains for 12 hours a day at weekends. There's Ed McCall, a successful broker, who liked running up stairs so much he introduced his teenage sons to it: the three now combine school and work with travelling to races all over the world. And there's Tim Van Orden, who feels compelled to break records in a host of athletic endeavours, and to show the world (via his website runningraw.com) that all of this can be done on a raw vegan diet.

Their motives for taking up the sport may differ, but tower runners all talk of one universally shared experience - the pain. "It's not all that pleasant," says Ed McCall. His son, Colin, adds: "After my first race, I puked in a garbage can. Everyone high-fived me." "Think about the most painful thing you've ever done, then multiply by 10," says his elder brother Colin.

Most tower runners seem to have found the sport by accident. "I was a mountain runner training for the US team back in the fall of 2006," says Van Orden. "At the time, mountain running was the most gruelling sport I could find. But I injured my knee, and thought I was going to be out for a few months, until I discovered that I could climb stairs without aggravating it. A friend had mentioned that they held a stair climb race in the US Bank Tower in downtown LA and suggested that I give it a try. Somehow I managed to get third place overall. I had never experienced so much pain in my life - but I was hooked." Not everyone achieves such success in their first event. Tower runners love to relate stories of elite marathon runners who assume they'll cruise to the top, only to drop out in a crumpled heap on the 43rd floor.

One "flat" athlete who has succeeded at more vertical pursuits is Austrian Andrea Mayr. As well as being the Austrian record holder for the women's 3,000m steeplechase, Mayr is a multiple winner of the Empire State Run Up and the Taipei 101, the sport's most prestigious events, and sees it as useful endurance training on a road that she hopes will take her to Beijing this summer. Even she - a seasoned athlete - complains of the pain of tower running: "After the first half your legs get tired, and at the end the muscles really burn. It's really, really tough."