3 months bed rest: Med Uni Graz examines bones

What happens to the human body during prolonged bed rest or weightlessness? The European Space Agency (ESA) is conducting so-called "bed rest studies" to investigate whether and what changes occur when the body is at rest for an extended period of time. These bed rest studies are carried out at various locations throughout Europe and offer researchers from a wide range of disciplines the opportunity to investigate these unusual circumstances in healthy test subjects. Ines Fößl from Barbara Obermayer-Pietsch’s research team at the Department of Endocrinology and Diabetology at the Medical University of Graz is investigating whether and which changes occur in the bone structure of the male study participants in 24 test subjects. A particularly high-resolution CT device used at the Medical University of Graz is helping with this.

90 days of rest

This special job is a reality for a total of 24 test subjects in Planica, Slovenia. The young, healthy men are not allowed to move from their beds as part of a bed rest study by the European Space Agency: They are only allowed to lean on their forearms for 30 minutes a day. The rest of the time they have to lie completely flat. Some of them complete various exercises lying down. With these studies, the European Space Agency wants to simulate the conditions of a long-term space flight and its effects as closely as possible. The exercises are intended to counteract the physical deterioration caused by lying down. However, these bed rest studies can also provide practical data outside of space research. So-called satellite projects can use these unique conditions to gain important insights, e.g. for long-term bedridden patients in intensive care units.

Focus on the bone

Ines Fößl and the team at Med Uni Graz are also conducting research on the participants in the bed rest study. They are taking a technical look inside the bones of the test subjects and observing whether and what changes are taking place inside the bones. In addition to the typical examinations and measurement protocols, a special research infrastructure is being used here. High-resolution peripheral quantitative computed tomography (HR-pQCT) can provide a unique insight into the bone structure of the study participants," says Ines Fößl, explaining the research with high-tech equipment.

The bone structure naturally plays an important role in physical function. The bones must not only be able to bear the load of the body (even when force is applied), but their interior (e.g. the bone marrow) also serves (depending on the type of bone) to form blood, i.e. to produce blood cells," says Ines Fößl, explaining the important tasks of the bones. The "hard" layer of bone (cortical bone) lies on the outside and differs in its structure from the bone space on the inside. This is criss-crossed by bone beads, so-called trabeculae, which are oriented along the lines of tension and load of the tissue in order to be able to withstand the loads as well as possible with a minimal mass of bone material. This means that the bone as a whole weighs less and provides space for blood production.

Extremely lively

Although bones are usually perceived as something very rigid and inflexible, they are actually living tissue that is constantly renewing and remodeling itself. Regular training and stress on the bones make them more resistant to fractures and keep them that way in old age. In this study, researchers at the Medical University of Graz are investigating how continuous bed rest affects these remodeling processes and thus ultimately also the structure of bones in healthy people.

Profile: Ines Fößl

Ines Fößl studied Molecular Microbiology and completed her doctorate at Med Uni Graz in 2021, where she currently works as a researcher at the Department of Endocrinology and Diabetology. Her focus is on bones, particularly the development and early detection of primary and secondary osteoporosis using imaging and molecular biology techniques. She is also a scientist at Joanneum Research COREMED, where she researches the effects of burns on the organism, particularly on the bones.