Space race: A marathon run 200 miles above the Earth

Some 38 years after Neil Armstrong took his "one small step for a man" on the surface of the Moon, Sunita Williams is getting ready to take several thousand - much quicker - steps for womankind while orbiting the Earth.

A week tomorrow, Commander Williams, a 41-year-old US Navy officer and Nasa astronaut, will be running the 26.2 mile distance of the marathon while aboard the International Space Station. She will be performing her remarkable feat 210 miles above the Earth and as competitor No 14,000 in the Boston Marathon.

When Alan Shepard whacked a couple of golf shots on the Moon, on the Apollo 14 mission in 1971, it was strictly for fun. When Commander Williams gets strapped on to the treadmill on the International Space Station, with her race number pinned to her vest, she will be taking sport to the outer limits.

The Boston Marathon is the world's oldest annual marathon (it was first held in 1897) and, unlike the London event, it has strict entry standards for its 24,000 participants. Having qualified for this year's race with a time of 3hrs, 29mins, 57 secs in last year's Houston Marathon, Commander Williams was not going to allow the small matter of a work assignment to prevent her from taking her place.

When she was chosen as one of the three-strong crew for ISS Expedition 14 - a six- month tour that started in December - she asked the race organisers, the Boston Athletic Association, if she could compete as a long-distant entrant. They agreed, forwarding her race number by email to the International Space Station.

"I consider it a huge honour to qualify and I didn't want my qualification to expire without giving it a shot," Commander Williams said.

Jack Fleming, spokesman for the Boston Athletic Association, said: "The Boston Marathon is the pinnacle of achievement for most runners and for Suni to choose to run the 26.2 miles in space is really a tribute to the thousands of marathoners who are running here on Earth. She is pioneering a new frontier in running, which will truly be out of this world."

Indeed, it will. The International Space Station, flying at a speed of 17,500mph, will orbit the Earth at least twice while Commander Williams pounds out the miles on the treadmill, to which she will be tethered by a harness with bungee cords.

"Running on the treadmill is a little tough," she said. "It's on a gyro - a vibration isolation system - so it kind of floats. The first time I got on it, I couldn't run a mile and my legs were wobbling. Now I've got up to about 15 miles on it and I feel pretty good.

"The reason we have the treadmill up here is because we need to exercise a lot to stop losing bone mass and muscle mass. You can't run as fast on it - I'm running 6mph - so it's going to take me longer than it did when I ran my qualifying time."

Still, if she manages to last the distance, Commander Williams will have another record to add to her CV: the fastest marathon out of this world. She holds the records for the most space walks by a woman (four) and for the most time spent on space walks by a woman (29hrs, 17mins). By the end of her present tour of duty she will also hold the Nasa record for the longest time spent in space by an astronaut of either sex.