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Astronauts and bedridden patients have much in common

A trip to space has about the same effect on the body as a prolonged stay in bed. Muscles, bones and circulation, are weakened. Therefore, Danish Aerospace Company A/S collaborates with robot scientist from the University of Southern Denmark, who develops training equipment for rehabilitation.

By Birgitte Dalgaard, , 2/16/2021

In 2015, Andreas Mogensen became the first Dane in space. Now there is another opportunity for a Danish astronaut. The European Space Agency (ESA) is looking for four new astronauts. At least one thing is certain. Onboard, the new astronauts should prepare themselves for training using training equipment supplied by Danish Aerospace Company A/S in Odense.

– You usually compare going into space with staying in bed for half a year. If you lie in bed for half a year, then you will not be able to stand on your feet. Nor can astronauts if they do not train whilst they are in space, points out director Thomas A. E. Andersen from the Danish Aerospace Company, which is the world leader in training equipment for astronauts:

– Astronauts typically experience a 10-20 per cent reduction in bone mass in space. Therefore, astronauts must return to Earth within 14 days if the exercise equipment breaks down.

You usually compare going into space with staying in bed for half a year.

Thomas A.E. Andersen, CEO

ESA has also previously conducted experiments with bedridden healthy people to measure how it affects muscles, bones and circulation.

– Danish Aerospace Company's expertise is to create strain where there is no strain. But when we train very sick patients with almost no muscle strength, it is important to remove strain, says researcher Anders Stengaard Sørensen from the Maersk Mc-Kinney Moller Institute.

For 10 years, Anders Stengaard Sørensen has worked with integrating robot technology with rehabilitation equipment for the frail elderly, where robot technology actively helps patients and complements the work of physiotherapists.

– Rehabilitation depends on a lot of repetitions of different exercises. It is the right job for a robot, says Anders Stengaard Sørensen.

Playing with gravity

He invented RoboTrainer; a rehabilitation robot in which a cord drive is connected to a computer, which automatically adjusts itself to help patients that have very little muscle power. For example, the robot helps to lift the patient's arm when the patient does not have the muscle strength to do so. In this way, patients gradually regain the feeling and strength in the body.

– In space, the astronauts need strain where there is no strain. Patients in a rehabilitation course need require the opposite. When we train people who are ill, there is too much gravity, so we have to come up with algorithms and adapt the patient's experience of gravity, Anders Stengaard Sørensen explains:

– With the RoboTrainer, we alter people’s perception of gravity. One can say that we create a form of virtual reality for the body.

With the RoboTrainer, we alter people’s perception of gravity. We create a form of virtual reality for the body.

Anders Stengaard Sørensen, lektor

Danish Aerospace Company discovered Anders Stengaard's work to incorporate robotic equipment and new technology for rehabilitation. The company can see the advantage of the intelligent cord drive because it does not take up much space and it will complement an exercise bike so that astronauts get the opportunity for the precise training of individual muscle groups.

– We have followed Anders' work that integrates new technology in training equipment. We absorb all the inspiration that we possibly can so that we can secure our position as a market leader. The core of our product is an exercise bike, which we have complemented, like RoboTrainer, with the use of an engine and electronic regulation, says Thomas A. E. Andersen from Danish Aerospace Company A/S:

Inspiring new knowledge

– We are also incredibly happy for the students from SDU who come to do an internship with us. Using them, we get the opportunity to pursue ideas that we otherwise would not have the resources for, and they inspire us with the latest knowledge and technology for the company. It provides an academic insight where critical questions can make us do things more smartly.

When ESA sends the next astronaut up, the name Danish Aerospace Company will certainly be written on the exercise equipment that he or she will need to exercise. The Danish Aerospace Company currently has a contract with both ESA and NASA for the supply of space bikes and health monitoring equipment, but the market is growing.

More and more space missions

– If you had asked me 10 years ago, then ESA and NASA were the only potential customers, but now we are experiencing a growing market, also within the private space industry. There are more and more space missions involving astronauts.

ESA seeks new astronauts

  • For the first time in 11 years, European Space Agency, ESA is looking for new astronauts.
  • The starting point for this is 31 March 2021, when the vacancies for new astronauts open. To expand gender diversity ESA is strongly encouraging women to apply.
  • The vacancy runs from 31 March to 28 May 2021 and ESA will only consider applications submitted to the ESA Career website within those eight weeks.
  • After that, the six-stage selection process will start, which is expected to be completed in October 2022

Source: ESA
Learn more at ESA's homepage

- There are more and more space missions involving astronauts. India is planning the country's first spaceflight, with astronauts, in 2022, while China is aiming for a lunar flight with astronauts in the year 2024, says Thomas A. E. Andersen:

- But there is also a need for rehabilitation in other extreme environments, for example in Antarctica or in submarines, where there is the same need for compressed training equipment that does not take up too much space.

But even though there are many analogies between training astronauts and retraining patients who have lost muscle strength after a long stay in bed, it is not a market that the Danish Aerospace Company yet have concrete plans to pursue.

– We have not actively pursued that market, but maybe one day, says Thomas A. E. Andersen.

Photo: Ritzau-Scanpix

Q&A: How does it affect the body to be in space?

We asked postdoc in muscle physiology and biomechanics, Jakob Lindberg Nielsen from the Department of Sports and Biomechanics.

How does it affect the body to be in space compared to lying in bed for longer period?

Some of the same things happen to the body, you lose muscle and bone mass. When you are in space or lying in bed for a long time, muscle and bone tissue are not exposed to the same mechanical strain that occurs when the muscles counteract gravity. Without us noticing it, our muscles constantly work against gravity when we stand, walk or get up. When we lie in bed or are in space, the muscles of the body are not exposed to the same mechanical strain and therefore they will gradually decay. This is also what you experience when you have had cast on for a long time. When the cast comes off, you typically lose a large part of the muscle mass because you have not had the opportunity to activate and therefore strain the muscles around the joint in question.

To what extent can we compare astronauts with bedridden people?

Concerning the breakdown of muscle, bone and tendon tissue, there are great similarities, but with regards to blood circulation, it is a little different. On Earth, gravity ensures that we usually have a large portion of the blood in our legs, but that changes when there is low gravity. Astronauts may experience more blood than usual to the brain and a drop in blood pressure. It can cause acute discomfort such as headaches, dizziness and ultimately, fainting. Over time, the body adapts to the reduced weight effect, and the acute symptoms disappear. The body adapts by reducing the amount of blood in the body, and at the same time, the heart becomes smaller. The same is seen over time in bedridden patients.

How fast is muscle mass lost?

It goes relatively fast. Some of my colleagues, in their studies, have observed a decline in muscle mass of up to 30 per cent in 7-14 days. It goes faster in young people and slower in older people. Bone and tendon tissue also break down, but at a slower rate.

Meet the researcher

Anders Stengaard Sørensen is an Associate Professor at SDU Health Informatics, The Maersk Mc-Kinney Moller Institute. He is behind the robotic training equipment RoboTrainer Light for the rehabilitation of weak patients.


Meet the researcher

Jakob Lindberg Nielsen is Postdoc in Muscle Physiology and Biomechanics at Department of Sports Science and Clinical Biomechanics. Has worked together with Anders Stengaard Sørensen in the development of robotic training equipment for patients.