On 15th of December 2015, millions of people watched as British Astronaut, Tim Peake, launched into space aboard Principia and became Britain's first official astronaut to fly to the International Space Station (ISS).
Mr Peake, previously an Army major and helicopter pilot, will spend six months on board the space station orbiting the Earth and he has spent six years training to become the first professional British astronaut to be employed by the European Space Agency.
However, no amount of training can fully prepare Tim Peake's body for the health risks which come with spending such a long period of time in space. In the next 6 months, Peake will expose his body to conditions very different to those back on Earth.
Despite the lack of gravity, the super-fit former test pilot has said he will run the London marathon whilst floating above a treadmill, using an iPad to virtually sprint through the capital's streets. But what other exercises are essential in order for Peake to remain in the best physical state he can for re-entry? Newitts takes a look below at how astronauts keep fit in space.
Fitness in space
On earth, a person's muscles and bones work against gravity. Even if you don't exercise as much as you should, you are still pushing against the force just to stay upright. When you are in space, the force is taken away and muscles can quickly start to waste away.
To minimize the physiological effects of microgravity, NASA has equipped the International Space Station (ISS) with a Resistance Exercise Device (RED) "tripod" system, which includes a space treadmill, a stationary bike and a device that simulates weightlifting.
It is important that astronauts spend approximately 2.5 hours per day keeping fit onboard the ISS, but even with this regime in place, those people who spend long durations in space such as Tim Peake, may return to Earth suffering from conditions such as muscular atrophy, cardiovascular deconditioning and bone loss that can be difficult to reverse.
Tim Peake will spend approximately 180 days in space which means that, according to NASA, his muscular strength could decrease by between 11 to 17 per cent, muscular endurance by 10 per cent and bone mineral density by 2 to 7 per cent.
Previously, astronauts' fitness could only be measured before and after ISS missions, but new ultrasound and panoramic imaging technologies now make it possible for crew members to take their own in-flight muscle measurements, so that trainers back on Earth can better monitor their fitness and alter personalized workout plans.
The Resistance Exercise Device (RED)
The RED system on the ISS is part of a tripod of equipment on board the Station which helps to offset loss of muscular strength through muscle and strength training, aerobic activity and cardiovascular training.
An astronaut's body will not encounter any resistance whilst in space, meaning that unlike terrestrials, they no longer have to use their legs to hold up their body weight, or pick anything up, and they can move from one side of the room to another with just a gentle push!
The RED system, brought onboard ISS in July 2013, is used to counterattack the muscular and skeletal problems brought on by extended time in microgravity. The system, according to NASA, functions like a weight machine in a gym on Earth with conventional weights replaced by vacuum cylinders that provide concentric workloads up to 600 pounds.
Astronauts can do upper and lower-body exercises, such as squats, dead lift, heel raises, bicep curls and bench press on the device and the treadmill uses clip harnesses to hold the astronaut down.
Health and fitness back on Earth
Coming back to Earth presents a list of new health challenges for astronauts, and several standard tests must take place during the first few weeks after an astronaut has landed. Balance tests, MRI scans and eye tests will all be performed regularly to monitor an astronaut's recovery.
Astronauts will follow a lengthy rehabilitation program with the main focus during the first few days on balance, blood flow and cardiovascular health. Astronauts must spend the first few days sat down, and even showers are taken place whilst sitting in a bath tub to prevent collapse. Under clothing, astronauts will initially wear a G-suit, to ensure blood pressure travels to the head.
A future mission to Mars
Combating bone loss is one of the challenges that the space program has if it is ever to achieve a successful mission to Mars. An ongoing study is currently measuring how much astronauts who stay on board the ISS for long periods of time should eat, and the appropriate level and type of exercise they should get.
But despite scientists making significant discoveries in figuring how to keep people fit and healthy on a six to nine month trip to Mars, experts are still a long way off figuring out the bone loss which would accumulate in a two year round-trip.