ABSTRACT
This chapter focuses on the study design and logistics of bed-rest studies as used in the main facilities conducting studies around the world trying to emphasize the factors affecting the results and why. The most used methods to simulate microgravity on Earth include immersion, bed rest, chair rest, isolation, hyperbaric environments and immobilization of animals. Toward the end of the 1960s, Soviet investigators evolved a new method of bed rest in which the subject was positioned with the head lower than the feet, rather than horizontal, after having analyzed subjective comments of cosmonauts received after flight. With the advent of human spaceflight in 1961, immersion in water was used as a logical model for reducing the pull of gravity on the mass of the body. Since the end of the 1960s, many bed rest studies have been conducted lasting from several hours to a maximum of 370 days. T.
