Background: In microgravity, an absence of axial loading upon the spine and associated structures result in significant stature elongation, an increased risk of disc herniation in both the lumbar and cervical intervertebral discs (IVD) and lower back pain. ESA’s Mk VI SkinSuit provides axial loading from shoulder to foot equivalent to ~20% bodyweight, in a cumulative manner analogous to Earth’s gravity. However, there is limited data to support the SkinSuit’s ability to minimise elongation and spinal changes in the early phases of spaceflight, with only one astronaut evaluation from a recent 10-day technological demonstration mission to the ISS. Aims: This study sought to determine the acute effects of the Mk VI SkinSuit upon elongation induced from post 8h Hyper-Buoyancy Flotation (HBF), a novel spaceflight analogue. Methods: Six males (31±4yr; 1.75±0.08m; 76.9±9.2kg) participated in two counterbalanced conditions, SkinSuit loaded and SkinSuit unloaded both laying for 8h on the HBF, a partly filled hypersaline waterbed that acts facilitate a buoyant, dry flotation. Stature was measured before (PRE) and after (POST) exposure. An MRI T2-weighted sagittal scan of the spine was analysed with OSIRIX; spinal length was determined with an open polygon measuring the distance between the C2 odontoid process and S1 superior endplate with lumbar length measured between the L1-S1 superior endplates. IVD heights were determined using the distance between the anterior/posterior edges of adjacent vertebrae. Cobb’s method evaluated lumbar curvature measuring the tangent between two horizontal lines drawn from L1-S1 superior endplates. Results: SkinSuit axial loading resulted in a tendency (p= 0.18) for reduced elongation POST 8h HBF (1.2±0.8cm vs. 2.1±0.6cm), with a significant attenuation (p<0.05) in both total spinal length (C2-S1:60.4±2.4cm vs. 60.8±2.5cm) and lumbar length (L1-S1:17.5±0.9cm vs. 17.8±0.9cm). Though no significant effects on IVD height or lumbar curvature were observed four participants experienced a minor increase in lumbar curvature with loading (p=0.25; 42.7±6.9o vs. 40.1±9.7o). Conclusion: The Mk VI SkinSuit resulted in a tendency for reduced elongation post 8h HBF. However, whilst this pilot study is unable to define the mechanisms by which stature increments are ameliorated, partly due to low power, data suggests the SkinSuit might have modulated the spines elongation response through slight IVD compression and support of lumbar curvature. This study evaluated the effects of the SkinSuit upon the spine during acute unloading representative of short-duration spaceflight, to inform SkinSuit utility for long-duration spaceflight the effects of reloading the spine require investigation.
|Title of host publication
|ISPG-ELGRA (European Low Gravity Research Association) Workshop Proceedings
|Published - 2 Oct 2017