Spinal column and midbrain integration for long duration space missions

Abstract

Background:  Deep space missions produce atrophied postural muscles and cognitive and proprioception losses. Lumbar and hip injury as well as limbic system dysregulation may result.  In microgravity, the Neutral Body Position is the spinal baseline for the prone-position cycle, where the astronaut’s lumbar muscles and audio and visual-spatial centers can be informed through a virtual reality interface. Methods: The exercise can be reproduced as a low-fidelity space simulation in a epsom-salt float tank. MRI and ultrasound imaging of the spine at the start of the 4-week program can be compared to the imaged results upon program completion.  Any contractile tightening would be evident in shortened IVD (intervertebral distances) in post-procedure MRI results. The terrestrial gravity cycling instrument  establishes an effective baseline for determining anthropomorphic tolerances, the necessary workout duration and resistance levels in zero gravity. Results: An exercise regimen performed on an ergonomically-designed cycle can limit the stresses to demineralized postural bones thus reducing the risk of in-flight and post-flight fractures.  The redistribution of spinal fluids is a specific focus of this exercise instrument.  It's postulated that the secondary effect of reduced spinal fluid shifts are lower optic nerve and cranial pressures and the tertiary effect is the reduction of neuro-cognitive and cardio-vascular stresses brought on by weightlessness.   Conclusions: The biomechanism of spinal fluid’s dynamic flow across a lower pressure gradient may be the cause of increased fluid volume in the spinal canal. This cycling exercise lessens the physical impact to areas of BMD depletion such as the hip socket.  The exercise can maintain spinal flexibility, fluid stasis and posture.   Human body systems affected by microgravity could be assisted with Virtual Reality (VR) inputs.  The limbic system receives comprehensive, targeted sensory information that enables reorganization of neuronal networks that may serve to change dysregulated human immune, spatio-temporal, and cognitive systems.