Tim Peake won't just be suffering from a lack of gravity when he attempts to run the London Marathon in space on Sunday.
The British astronaut, currently orbiting Earth aboard the International Space Station [ISS], will also be battling boredom, loneliness, and possibly even hunger as he trudges through 26.2 miles strapped to a futuristic treadmill.
While an elasticated harness will keep Peake's feet on the track, there are other elements of life in microgravity that the 44-year-old admitted could present unique problems for his record attempt.
"Food up here in microgravity doesn't settle very well," Peake explained from the ISS, 400km above the Earth's surface. "It tends just to stay floating around in your stomach.
"Our breakfast tends to run out quite quickly too. I might need to take some packets out and reserve them for Sunday morning. Maybe baked beans, sausage and eggs, but you certainly don't want to be running up here on a full stomach. It needs to be a good two or three hours after you've eaten."
While many runners down on Earth might recognise the perils of timing breakfast before a big race, at least those competing in London on Sunday won't be struggling for company as they take on the gruelling distance.
Rather than 38,000 running buddies, Peake will be relying on music and a video feed to keep him entertained during the three-and-a-half to four hours he says it will take him to complete the course.
"Unfortunately the treadmill isn't located by the window, so the one thing I won't be able to do is look at planet Earth as I run the marathon," Peake said. "But I'm pretty used to life on board the space station now. I have my other crewmates, who'll be popping in to Node 3 where I'll be running the race to cheer me on.
"I'll have some music to listen to, and I've got the RunSocial app, so I'll actually be looking along the route [of the marathon]. Also hopefully I'll get a telly sent up to the station as well, so at times I'll be able to see what's going on with the real race down in London."
The RunSocial app will allow Peake to follow the marathon route on his iPad alongside his teammates back on Earth as they attempt to raise awareness for the Prince's Trust. Mirroring Peake on terra firma will be Dr Jonathan Scott and Libby Jackson, aiming to break a world record for the fastest marathon wearing a space suit.
The first British man to walk in space, Peake admitted he could have trained harder for Sunday's race, but expects to recover far quicker from the aches and pains typically associated with the day after a marathon on Earth.
"I don't think you can ever do enough training for a marathon, but I've been putting in the miles on the T2 treadmill up here on the Space Station," Peake said. "I've done a few half marathons, but I'm sure there will be a few points where I wish I'd done a bit more training.
"In terms of recovery from the race, weightlessness is one of the perfect environments because, the moment you stop running and get off that bungee system, your muscles are in a relaxed state. We recover faster up here from any aches or sprains to the muscular system."
Peake will become the first man to run a marathon in space, but not the first human. NASA astronaut Sunita Williams holds that honour after completing the Boston Marathon in 2007.
Williams' space record clocks in at 4 hours 23 minutes 10 seconds, which Peake stands a strong chance of beating. His personal best for his previous marathon attempt -- albeit on Earth in 1999 -- is 3 hours 18 minutes.
Spare a thought for Peake's five crewmates aboard the space station, who are likely to have to put up with a slightly smellier colleague than normal after his record attempt.
"Cleaning in space is just a little bit like camping," Peake added. "We have hot water dispenser and flannels. That does the job for all of our personal hygiene.
"Luckily I'm running right next to the loo up here on the space station, so there's unlikely to be a queue for it!"