The initial results of the Long-Term Bed Rest Study performed in 2001 and 2002 by the European, French and Japanese space agencies, reveal interesting first findings for spaceflight and healthcare in general. The main objective of the Long-Term Bed Rest Study was to assess changes to muscle and bone arising typically on long-duration spaceflights and to evaluate methods for counteracting such changes.

The study was based on the anti-orthostatic (–6° head-down tilt) bed-rest model and involved a total of 25 volunteers remaining in the tilt-down position for a total of
90 days. The –6° head-down tilt position has been shown to be the best for simulating the effects of the weightless environment of space. The total duration of each campaign was 120 days: 90 days in a strict –6° head-down tilt, with a preparatory period of 15 days beforehand and a 15-day recovery phase after.

During the study subjects underwent a number of physiological investigations, including tests during exercise, osteodensitometry (measurement of bone density) and magnetic resonance imaging. Analysis of muscle biopsies and extensive biochemical analysis of biological samples were also performed.

The research protocols were proposed by European investigators in response to an ESA announcement of opportunity, and by NASDA scientists mainly for the research into bone physiology. Over 60 scientists from eight ESA member states and from Japan participated in this study.

The preliminary results from the Long-Term Bed Rest Study show that subjects who exercised (only a few minutes of intense exercise every three days) during a 90-day period were least affected by muscle and bone deterioration. This was found to be the case in particular with regard to muscle mass and strength. Loss of bone mineral content in weight-bearing bones such as the legs was observed by this microgravity simulation study. The preventive administration of the anti-osteoporosis drug bisphosphonate was also found to play an important role in reducing the effects of simulated weightlessness on bone loss.

One year after the study, the experiment subjects are still being monitored and data analysis is continuing. It is expected that the study will produce a large number of important publications in this field.

“The Long-Term Bed Rest Study project reflects ESA’s continued commitment to the advancement of space for life,” said Jörg Feustel-Büechl, ESA’s Director of Human Spaceflight. “It demonstrates the way in which space related research can help to solve terrestrial problems.”

This Long-Term Bed Rest study is the most complex and the longest head-down tilt bed-rest study ever undertaken in Europe. It has important implications for the development of preventive countermeasures intended to overcome the adverse effects of long-duration spaceflight.

From the medical viewpoint, the study should improve knowledge of the effects of immobilisation and/or inactivity on the cardiovascular system and on bone and muscle tissue. This will help improve the treatment and recovery of hospitalised or bedridden patients.

A meeting with the team at the MEDES space medicine and physiology institute and volunteers participating in the second bed-rest campaign will take place in Toulouse on 16 January 2003 at 3.00 p.m. at the Cité de l’Espace.