[Some physiological effects caused by 30 days of bed rest in different body positions]

Eighteen male test subjects were exposed to a 30-day bed rest with the foot end of the bed tilted at +6 degrees, -2 degrees or -6 degrees. Control subjects were allowed a normal mode of life during the same period of time. Hypokinesia was shown to play the leading role in the genesis of most changes, since control subjects displayed no changes. It was concluded that head-down tilt simulated changes occurring during adaptation to weightlessness better than recumbency or head-up tilt.