18/09/2012 04:33 BST | Updated 17/11/2012 05:12 GMT

Astronaut Sunita Williams Completes Triathlon In Space

A Nasa astronaut has completed the first triathlon in space.

Astronaut Sunita Williams finished the running, cycling and 'swimming' race using specialised equipment aboard the International Space Station.

She timed the event to coincide with the Nautica Malibu Triathlon held in Southern California.

Williams is the commander of Expedition 33 on the ISS, about 240 miles above the Earth.

She used a stationary bike, a treadmill and a "strength training machine" tuned to a weightless environment to simulate the triathlon. The training machine was used in lieu of swimming, which is not possible in zero gravity.

In total she 'swam' half a mile, cycled 18 miles and ran four miles.

"I'm happy to be done," she said after the race. "It wasn't easy, and I'm sure everybody in California's very happy to be done too."

"A big shout out to our astronaut strength and conditioning folks, who were really interested in this and who got this whole workout together," she added.

Williams was last on the ISS in 2007 where she again showed up those of us back on Earth by running a marathon in space, finishing in four hours and 23 minutes.

WIlliams and her crewmates, Yuri Malenchenko of Russia and Akihiko Hoshide of Japan, will return from the ISS in November.