On Sunday morning, British Astronaut Tim Peake will partake in the London Marathon, but he will do so 250 miles above the streets of London while aboard the International Space Station.
Peake will be running on a treadmill aboard the station, and if he succeeds, he will be the first man to run a marathon in space.
Peake will not be the first person to run a marathon from space, though, as U.S. Astronaut Sunita Williams participated in the Boston Marathon in 2007 while aboard the station.
This will be Peake's second time running the London Marathon. His first time was in 1999 when he finished the race in a little over three hours.
In an interview with the Associated Press, Peake said that he will not be challenging his personal record and is aiming to complete Sunday's race in a little under four hours.
With the International Space Station whizzing around the earth at over 17,000 mph, more than 22 times the speed of sound, the station will orbit the Earth nearly 3 times by the time that Peake finishes his 26.2-mile run on the treadmill.
Although Peake will only be the second astronaut to run a marathon in space, every astronaut runs on a daily basis during their stay on the International Space Station.
Early in the space program for the United States, astronauts were in space for only short periods of time and did not exercise while on their mission to the final frontier. However, this changed once astronauts began spending longer periods of time in space.
According to NASA, "Exercise is an important part of the daily routine for astronauts aboard the station to prevent bone and muscle loss."
"On average, astronauts exercise two hours per day," the agency added.
However, exercising while in space is much different than on Earth. Without the pull of gravity, special equipment is required for astronauts to receive the workout they need to stay in shape.
The Combined Operational Load Bearing External Resistance Treadmill, or COLBERT, is one of these special pieces of equipment aboard the space station.
"Without gravity to hold the runner to the surface of the treadmill, designers call on elastic straps that fit around the shoulders and waist to keep the runner from rocketing across the space station with the first hard step," NASA said.
The pull of these elastic straps simulates the pull of gravity.
Running on a treadmill will not be the only difference between Peake and the rest of the marathon runners. While Peake is running in the controlled environment of the space station, the thousands of people running in London will be doing so in chilly winds and showery weather.
This type of weather could impact the times of runners.
"Temperatures will be near only 6 C (43 F) at the start of the race with a high of 10 C (50 F) during the afternoon, which would make it one of the coldest London Marathons on record," AccuWeather Meteorologist Eric Leister said.