THU0423 Immobilization Simulating Weightlessness Affects Immunological Parameters

Background Exercise has a wide variety of beneficial health effects. It stimulates bone formation and maintains bone strength as well as decreases the risk of falls. Moreover, exercise at regular intervals is also assumed to positively affect immune functions. Conversely, in more than 50% of the astronauts during/after space flight and under simulated weightlessness immune functions are suppressed. Objectives To assess the effects of simulated weightlessness during the 2nd Berlin BedRest Study (BBR-2) on immunological parameters. Furthermore, to compare the effects of two different exercise performances (resistive vibration exercise and resistance exercise without vibration). Methods 24 physically and mentally healthy male volunteers (20-45y) experienced 60-days of six degree head down tilt bed rest. They were randomized to 3 groups: resistive vibration exercise (n=7), resistance exercise without vibration (n=8), inactive controls (n=9). Blood samples were taken 2 days before bed rest, on day 19 and 60 after beginning of bed rest. Composition of immune cells was analyzed by flow cytometry. Cytokines and neuroendocrinologic parameters were analyzed by a multiplex suspension array/ ELISA in plasma. General changes over time were identified by paired t-test, exercise-dependent effects by 2-group repeated measurements ANOVA. Results For all cases pooled, the number of granulocytes (p