If you think running a marathon on Earth is pretty tough, British astronaut Tim Peake has set the bar even higher -- literally. The ESA spaceman set a new world (rather, space?) record yesterday as he finished a marathon in record time aboard the International Space Station (ISS).

Peake finished the London Marathon with some 39,000 runners racing 250 miles (400 kilometers) below the space station. Strapped to a treadmill with a simulation of the London route on his iPad, the first British European Space Agency (ESA) astronaut ran a total of 26.2 miles (42 kilometers), according to The Associated Press.

Before Sunday's race, Peake sent a video message wishing the participants good luck, particularly his ground team called #teamastronaut, who are racing for charity called The Prince's Trust, which supports England's disadvantaged youth.

In the morning of the race, Peake posted a Twitter update, asking Londoners if they "fancy a run" with a stunning photo of London seen from the space station.

Armed with water pouches lined and velcroed to a panel above his head, Peake made sure to stay hydrated during the run. He said on his official blog at ESA that he drank a pouch per hour, which contained 300 ml of water, to keep him going. Peake was also equipped with his Spotify playlist, aptly titled #spacerocks. (Give it a listen HERE!) He had a solid support team over at ESA, who monitored and gave updates on his run over Twitter, and also the support of #teamastronaut running alongside him, with two race participants running in replica Russian suits.

The Brit astronaut completed the marathon at 3 hours, 35 minutes and 21 seconds, earning him a Guinness World Record. He beat a previous record of 4 hours and 24 minutes held by NASA astronaut Sunita Williams who ran the Boston Marathon in 2007.

Peake's astounding record in space did not beat his earthly record, though. According to BBC, he ran his first London Marathon in 1999 and completed it in 3 hours, 18 minutes and 50 seconds, minutes faster than his space record.

But during his space marathon run, the ISS covered about 100,000 kilometers or more than 62,000 miles. At that rate, Peake had already circled the Earth twice.

The spaceman also faced a lot of challenges for this run -- aside from a windowless view. According to The Guardian, the harness system that strapped him to the treadmill puts the weight on his hips and shoulders, pulling him down in a different way than gravity does.

While in space, astronauts exercise for about two hours a day to keep their muscles from deteriorating. Although Peake was already a runner before his space mission, he still had to undergo special training for his one-of-a-kind race.