Bed Rest (IMAGE) National Space Biomedical Research Institute Caption For five weeks, participants lie at a six-degree angle and leave the bed only when performing exercise training. In this position, subjects show physiologic changes similar to those expressed by astronauts in microgravity for long periods. Credit UTSW Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.