Elmann-Larsen Benny, Schmitt Didier
Life Sciences Unit, ESTEC, Noordwijk, The Netherlands.
ESA Bull. 2003 Feb;113:34-9.
Since Yuri Gagarin's historic first flight into space in April 1961, it has quickly become evident that the space environment influences the human body in many different ways and causes it to adapt in ways that can lead to problems when returning to Earth's gravity. Much research has been performed in the meantime and our understanding of what happens to our bodies in space improved considerably during the Mir space station and Space Shuttle/Spacelab era. However, many questions, particularly regarding how to counteract those changes that we now know take place, still need to be addressed through studies on the International Space Station (ISS) and through simulations on the ground. As we enter an era in which crews will spend longer periods in space on the ISS and of longer term plans by almost every space-faring nation for missions to Mars, it is clear that much more knowledge is needed, and quickly. Although a few hundred men and women have already travelled into space, the operating environment severely limits the amount of systematic research that can be performed--a situation that is unlikely to change. Other avenues for addressing specific scientific questions in a controlled research environment must therefore be found. One of these complementary alternatives is head-down-tilt bed-rest studies in which volunteers are confined to beds that are tilted -6 deg below the horizontal at the head end. Every activity, including eating, reading, showering, etc., is performed in this position for the duration of the study. This leads to changes in the human body that are very similar to those seen during spaceflight, such as bone-mass and muscle-mass loss, cardiovascular and neuro-sensory deconditioning. The controlled bed-rest setting therefore allows meaningful research into the bodily consequences of spaceflight and possible countermeasures. It also gives the scientific community interested in space-related medical research more ready access to a clinical model. The benefits of these studies go far beyond their space application. Patients bed-ridden because of illness or accidents suffer the same symptoms and can thus also profit from the studies. As a clear indication of this link, the clinicians and researchers involved in the bed-rest campaigns typically spend the majority of their time exploring "terrestrial" problems.
自1961年4月尤里·加加林历史性地首次飞入太空以来，很快就明显看出，太空环境以多种不同方式影响人体，并使其以一些在返回地球重力环境时可能引发问题的方式进行适应。在此期间进行了大量研究，在和平号空间站以及航天飞机/太空实验室时代，我们对人体在太空中的变化情况的了解有了显著提升。然而，许多问题，尤其是关于如何应对我们现在已知会发生的那些变化的问题，仍需通过在国际空间站上开展研究以及在地面进行模拟来解决。随着我们进入一个宇航员将在国际空间站上停留更长时间的时代，并且几乎每个航天国家都有前往火星的长期任务计划，显然我们迫切需要更多知识。尽管已有数百人进入过太空，但操作环境严重限制了能够进行的系统研究数量——这种情况不太可能改变。因此，必须找到其他在可控研究环境中解决特定科学问题的途径。其中一种补充性的替代方法是头低位卧床休息研究，即让志愿者躺在床头向下倾斜6度的床上。在研究期间，包括饮食、阅读、淋浴等所有活动都在这个姿势下进行。这会导致人体发生与太空飞行期间非常相似的变化，比如骨质和肌肉量流失、心血管和神经感觉功能失调。因此，可控的卧床休息环境能够对太空飞行对身体的影响以及可能的应对措施进行有意义的研究。它还为对太空相关医学研究感兴趣的科学界提供了更便捷地接触临床模型的机会。这些研究的益处远远超出其在太空领域的应用。因病或因事故卧床的患者会出现相同的症状，因此也能从这些研究中受益。作为这种联系的一个明显迹象，参与卧床休息研究活动的临床医生和研究人员通常将大部分时间用于探索“地面”问题。
