Plehuna Anastasija, Green David Andrew, Amirova Liubov E, Tomilovskaya Elena S, Rukavishnikov Ilya V, Kozlovskaya Inessa B
King's College London, Centre of Human & Applied Physiological Sciences, London, United Kingdom.
Laboratory of Gravitational Physiology of the Sensorimotor System, Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia.
Front Physiol. 2022 Oct 13;13:1039924. doi: 10.3389/fphys.2022.1039924. eCollection 2022.
Microgravity induces spinal elongation and Low Back Pain (LBP) but the pathophysiology is unknown. Changes in paraspinal muscle viscoelastic properties may play a role. Dry Immersion (DI) is a ground-based microgravity analogue that induces changes in m. superficial myofascial tissue tone within 2 h. This study sought to determine whether bilateral m. tone, creep, and stiffness persist beyond 2 h; and if such changes correlate with DI-induced spinal elongation and/or LBP. Ten healthy males lay in the DI bath at the Institute of Biomedical Problems (Moscow, Russia) for 6 h. Bilateral lumbar (L1, L4) and thoracic (T11, T9) trunk myofascial tone, stiffness and creep (MyotonPRO), and subjective LBP (0-10 NRS) were recorded before DI, after 1h, 6 h of DI, and 30min post. The non-standing spinal length was evaluated on the bath lifting platform using a bespoke stadiometer before and following DI. DI significantly modulated m. viscoelastic properties at L4, L1, T11, and T9 with no effect of laterality. Bilateral tissue tone was significantly reduced after 1 and 6 h DI at L4, L1, T11, and T9 to a similar extent. Stiffness was also reduced by DI at 1 h but partially recovered at 6 h for L4, L1, and T11. Creep was increased by DI at 1 h, with partial recovery at 6 h, although only T11 was significant. All properties returned to baseline 30 min following DI. Significant spinal elongation (1.17 ± 0.20 cm) with mild (at 1 h) to moderate (at 6 h) LBP was induced, mainly in the upper lumbar and lower thoracic regions. Spinal length increases positively correlated (Rho = 0.847, = 0.024) with middle thoracic (T9) tone reduction, but with no other stiffness or creep changes. Spinal length positively correlated (Rho = 0.557, = 0.039) with Max LBP; LBP failed to correlate with any m. measured parameters. The DI-induced bilateral m. tone, creep, and stiffness changes persist beyond 2 h. Evidence of spinal elongation and LBP allows suggesting that the trunk myofascial tissue changes could play a role in LBP pathogenesis observed in real and simulated microgravity. Further study is warranted with longer duration DI, assessment of IVD geometry, and vertebral column stability.
微重力会导致脊柱伸长和腰背痛（LBP），但其病理生理学尚不清楚。椎旁肌粘弹性特性的变化可能起了一定作用。干浸（DI）是一种地面模拟微重力模型，可在2小时内引起浅表肌筋膜组织张力的变化。本研究旨在确定双侧肌肉张力、蠕变和刚度在2小时后是否持续存在；以及这些变化是否与DI诱导的脊柱伸长和/或LBP相关。10名健康男性在俄罗斯莫斯科生物医学问题研究所的DI浴中躺6小时。在DI前、DI 1小时后、DI 6小时后和DI后30分钟记录双侧腰部（L1、L4）和胸部（T11、T9）躯干肌筋膜张力、刚度和蠕变（MyotonPRO）以及主观LBP（0-10数字评分量表）。在DI前后，使用定制的身高计在浴升降平台上评估非站立位脊柱长度。DI显著调节了L4、L1、T11和T9处肌肉的粘弹性特性，且无侧别效应。在L4、L1、T11和T9处，DI 1小时和6小时后双侧组织张力均显著降低，且降低程度相似。DI在1小时时也降低了刚度，但L4、L1和T11在6小时时部分恢复。DI在1小时时增加了蠕变，6小时时部分恢复，尽管只有T11处显著。DI后30分钟所有特性均恢复至基线。诱导出显著的脊柱伸长（1.17±0.20厘米），伴有轻度（1小时时）至中度（6小时时）的LBP，主要发生在上腰部和下胸部区域。脊柱长度增加与中胸部（T9）张力降低呈正相关（Rho = 0.847，P = 0.024），但与其他刚度或蠕变变化无关。脊柱长度与最大LBP呈正相关（Rho = 0.557，P = 0.039）；LBP与任何测量的肌肉参数均无相关性。DI诱导的双侧肌肉张力、蠕变和刚度变化在2小时后仍持续存在。脊柱伸长和LBP的证据表明，躯干肌筋膜组织变化可能在真实和模拟微重力下观察到的LBP发病机制中起作用。有必要进行进一步研究，采用更长时间的DI，评估椎间盘几何形状和脊柱稳定性。
