Fig. 1.

Study design. Prior to the bed rest phase, participants spent 14 days in the bed rest facility for familiarisation and baseline data collection (BDC-14 through BDC-1). In the morning of the first head-down tilt bed rest day (HDT1), participants were randomly assigned to one of the two intervention groups (cAG, 30 min of daily centrifugation during the 60 days of bed rest; iAG, 6 × 5 min of daily centrifugation interspersed with breaks of 3 min each) or the control group (CTRL). After the 60 days of HDT bed rest, participants were re-ambulated and stayed for an additional 14 days in the bed rest facility for measurements and recovery (R + 0 through R + 13)