Overview
Exposing humans to microgravity has severe implications on their health. Low back pain for example emerges in flight and impairs the performance of the astronauts substantially (Sayson and Hargens, 2008). It is assumed that microgravity induces a swelling of the lumbar intervertebral discs (IVD), which causes the low back pain (Sayson and Hargens, 2008). New reports are claiming, however, that mechanisms involved in stabilizing the spinal cord might be the main reason for the pain, rather than the disc swelling (Bailey et al. 2018; Chang et all. 2016). Additionally, an important topic that has not yet been extensively addressed is the motor control challenged that astronauts suffer when exposed to different spine loading/unloading. For maintaining the balance of the upright body and the ability to adapt to changes in gravity and/or additional loading, a healthy motor control of the spine is essential (Mergner and Rosemeier, 1998; Roijezon 2015; Treleaven 2017). It is obvious that gravity plays a key role in this spinal motor control system. Last but not least, it has been shown that movement kinematics change in response to decrease of microgravity but more research is needed to explain the processes behind those changes (Roll 1998; Crevecoeur 2010)
This project will investigate the microgravity-induced changes in the human spine to gain a deeper understanding of the aforementioned knowledge gaps. Measurements of lumbar spinal motor control (stiffness and motion patterns) and ultrasonic examination of the discs (with and without load) of astronauts will be performed before and after the mission. To understand the results and corroborate the findings, the science team will also perform a Ground Reference Experiment that will culture IVDs from cow tail in a microgravity simulator – a Random positioning machine (RPM). IVD from the cow tail is an excellent model for human IVDs because it represents the physiological and physical properties in humans very closely. Several studies are showing that the IVDs of the astronauts degenerate while in space (Chang et al. 2016). By investigating isolated bovine IVDs that experienced similar microgravity exposure to that of the astronauts, a more profound knowledge of potential degenerative processes at the tissue and cell levels can be obtained.
