NASA astronaut Sunita Williams has completed the Boston Marathon in an unofficial time of four hours and 24 minutes, despite being strapped to a treadmill in orbit on the International Space Station.

Williams qualified for the Boston Marathon with her three hour 37 minute run in the 2006 Chevron Houston Marathon. She said she hoped the run would inspire kids to make fitness part of their daily lives.

"I think a big goal like a marathon will help get this message out there," she said.

Back on Earth, Russian Lidiya Grigoryeva won the women's race, finishing 48th overall with an official time of 2:29:18.

The men's title was taken by Robert K Cheruiyot, who crossed the line in 2:14:13. Kenyan Cheruiyot set a new course record of 2:07:14 last year. Commenting on this year's performance, he said it was not possible to set a good time in Boston if a north-easterly was blowing.

Williams, of course, did not have to do battle with the elements, but she did have to deal with the friction from the straps holding her to the treadmill.

Fellow NASA astronaut Karen Nyberg, Williams' sister Dina Pandya, and long-time friend Ronnie Harris all offered their support from Earth by running "with" Williams in the Boston marathon.

The Boston Marathon is unusual among the big city marathons in that runners must qualify for a place by completing another marathon in a specified time. As such it is held in high esteem by serious runners. Most city marathons select participants by lottery, or on a first-come, first-served basis. ®

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