How bed rest and cycling in artificial gravity are being tested to aid human spaceflight – NASASpaceFlight.com

How bed rest and cycling in artificial gravity are being tested to aid human spaceflight - NASASpaceFlight.com

For two months, 12 people from France will undergo a mandatory recumbent lifestyle to study the impacts microgravity has on astronauts and whether pedaling in artificial gravity could combat the negative effects human spaceflight has on the body. The Bedrest with Artificial Gravity and Cycling Exercise (BRACE) is led by the European Space Agency (ESA) and the French Space Agency (CNES) and will mark the first bed rest study involving cycling in Europe.

The project gathered 3,000 expressions of interest from volunteers in France, but after a long selection process 12 people were selected who are currently preparing for 60 days in bed, with one shoulder always in contact with the mattress, inclined six degrees below the horizontal line with feet up, in the name of science.

NSF met with Dr Angelique Van Ombergen, ESA’s head of life sciences in human and robotic exploration, to discuss what BRACE is and how it could benefit human spaceflight.

What is BRACE?

With the number of human spaceflight missions growing each year, studying the physiological effects of microgravity on the human body has become critical to keeping astronauts healthy in space.

Putting them to bed for that long and tilting them six degrees down induces processes in the human body similar to what astronauts are exhibiting in space, said Dr. Angelique Van Obergen.

Volunteers will participate in one of three categories: stay in bed all the time, stay in bed for an additional 30 minutes per day of cycling, or stay in bed for more than 30 minutes per day of cycling in the artificial gravity centrifuge. Everything from meals, to bathroom breaks and showers will be done while lying down.

Studies on bed rest aren’t new, but they’ve garnered more attention in recent years. Indeed, in November 2021, NASA awarded the Deutsches Zentrum fur Luft-und Raumfahrt (DLR) in Germany $49.9 million to support further studies of bed rest.

This latest project follows a similar project conducted in 2019, in which ESA, NASA and Germany completed the first-ever study of the artificial gravity bed to see if it had an impact on the deterioration of the human body in space. Like BRACE, the previous study placed participants in a spinning artificial gravity centrifuge for 30 minutes a day to determine whether the spinning could counteract the negative effects of microgravity. Dr. Van Obergen said the project’s preliminary results have not been as beneficial as hoped, but he believes BRACE could produce a better result.

This BRACE study is basically a follow-up in the sense that we are looking at a combination of artificial gravity and cycling exercise versus cycling alone to see if there is an additional effect of artificial gravity and to better understand whether it may be a potential benefit or additional benefit to save [astronauts] from the unwanted changes we see in bed rest that mimic some of the physiological changes in spaceflight, said Dr. Van Obergen.

Volunteer entered in the wall bike category. (Credit: ESA)

Participants assigned to cycle without the artificial gravity centrifuge will be lifted out of bed once a day and cycled for 30 minutes on a wall-mounted device. Participants assigned to artificial gravity will be wheeled out of bed to lie in the centrifuge and cycle for 30 minutes, while being spun to push blood to their feet, doubling the pull of gravity.

We encourage volunteers to reach maximum effort cycling, then compare the impact with those who don’t cycle at all, explains Rebecca Billette, clinical research lead at MEDES, the Institute of Space Medicine and Physiology in Toulouse, France.

The study involves 14 different European scientific teams and is taking place at the MEDES Space Clinic in France.

We’ll compare the impact of a daily exercise routine on a variety of physiological factors, Billette added.

The BRACE study begins in France. (Credit: ESA)

Bed rest and human spaceflight

Long-term bed rest has been touted as an effective way to mimic the body’s response to weightlessness. Several bodily changes during bed rest are spatially similar, such as blood flow to the head, fluid shifts, and bone and muscle loss. According to NASA, without gravity pulling blood flow to the legs, astronauts’ heads are filled with fluid, causing swollen bird’s feet syndrome.

We hope to understand the added value of artificial gravity to the fitness routine astronauts follow on the International Space Station (ISS). The crew exercises two hours a day in orbit. It [artificial gravity] it could become an effective solution for a healthier body during long-duration space missions if the technological challenges can be overcome, said Dr. Van Obergen.

The main benefit of performing these bed rest tests on Earth is that there are far fewer costs.

We have a lot less constraints and logistics, and we don’t need to think about uploads or downloads or anything like that. We don’t need to think about mass, we can test more subjects in a shorter amount of time, which is obviously very important in biomedical research. We can test or validate countermeasures that we can then test in space. So, I think there are many benefits to doing these field studies to inform real space missions,” said Dr. Van Obergen.

However, while bed rest provides a good representation of the human body in space, its effectiveness is limited.

When we put subjects on Earth in a bed for that long, there’s disuse of their bones and muscles, and that’s why they deteriorate, but the gravity is still there, he said. Whereas in space, astronauts are actually quite active, but their muscles and bones still deteriorate because there is no gravity acting against the muscles or affecting the metabolism of their bones.

In a 2016 study published by the American Physiological Society called Long-Term Bed Rest as an Analogue to Microgravity, the authors noted that more body surface area is compressed in bed rest than in space.

The volunteer undergoes rigorous testing during the 60 days of bed rest. (Credit: MEDES)

In true microgravity, external compression of all body surface areas is minimal, while bed rest generates greater compression of tissues over a greater surface area of ​​the body. This increased compression increases tissue pressures and likely dehydrates load-bearing areas due to increased interstitial flow in the microcirculation, the paper explained.

Despite these warnings, Dr. Van Obergen said bed rest remains a strong model for validating technology that could benefit human spaceflight.

The ups and downs of 60 days in bed

The 12 volunteers will be treated like human guinea pigs for two months and will be poked and prodded all day, Dr. Van Obergen said. ESA and CNES went through a vigorous process to find their participants, filtering out those who might have certain neurological, bone or muscle diseases.

The main criteria for selection were that the volunteers had to be male, aged 20 to 45, in good physical shape with a body mass index between 20 and 27, and non-smokers.

Once the 60 days begin, each participant will be placed in their own category: cycling, artificial gravity cycling, or bed rest. While participants are given detailed information about what they will experience, the category they are placed into will be completely randomized, which, according to Dr. Van Obergen, can be psychologically challenging.

Artificial gravity centrifuge at DLR in 2019 study. (Credit: DLR)

Participants will follow a very standardized routine, said Dr. Van Obergen. They will be woken up at the same time every day. They will take their meals at the same time. Their meals will be very standardized, [and] will be measured in terms of nutrients present. They need to eat a specific portion of that food to make sure they’re getting enough nutrients, she said.

Even when they’re done eating, teams will calculate what’s left on their plate to analyze the most accurate representation of what’s entered their body, which will impact their results.

In addition to the 30 minutes of exercise for the two groups, their days will be filled with tests, such as muscle biopsies, urine samples, scans to check body composition, data collection to check blood pressure, heart rate, absorption of nutrients, energy expenditure, bone mass and mood.

Participants will have their time, but Dr. Van Obergen says it will be difficult. Participants are encouraged to set goals, such as learning a new language or taking an online course, to combat boredom.

Volunteer placed on the bed inclined six degrees to mimic the feeling of weightlessness. (Credit: DLR)

From a physical point of view, you are deteriorating to some extent from being in bed for so long and you may feel some discomfort or some things that are uncomfortable, maybe even some pain. At the same time, you are asked to participate in all investigations, which are sometimes quite invasive or might be a little painful, says Dr. Van Obergen.

In early 2024, ESA and CNES will conduct a second part of the same study with 12 other participants. The agencies will then have a total of 24 people to analyse. The next project will be another 60-day study in Slovenia focusing on the combination of vibration exercises and artificial gravity, ESA explained.

After 60 days, participants will undergo 14 days of post-rest recovery and monitoring. The study began on April 4 and will conclude in early July.

(Main image: BRACE bedrest volunteer placed in an artificial gravity centrifuge. Credits: ESA)


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