Clément Gilles, Moudy Sarah C, Macaulay Timothy R, Mulder Edwin, Wood Scott J
KBR, Houston, TX, United States.
Aegis Aerospace, Houston, TX, United States.
Front Physiol. 2024 Sep 6;15:1442239. doi: 10.3389/fphys.2024.1442239. eCollection 2024.
Bed rest can be used as a ground-based analog of the body unloading associated with spaceflight. In this study, we determined how strict head-down tilt bed rest affects subjects' performance of functional tests (sit-to-stand, tandem walk, walk-and-turn, dynamic posturography) that challenge astronauts' balance control systems immediately after they return from space.
Forty-seven participants were assessed before and a few hours after 30 days of 6° head down tilt bed rest at the DLR:envihab facility. During this bed rest study, called SANS-CM, the participants were divided into 4 groups that either a) were positioned in head-down tilt continuously throughout the 30 days; b) sat upright for 6 h a day; c) were exposed to lower body negative pressure (LBNP) for 6 h a day; or d) exercised for 60 min and then wore venous-occlusive cuffs for 6 h a day.
Results showed that strict head-down tilt bed rest caused deficits in performance of functional tasks that were similar to those observed in astronauts after spaceflight. Seated upright posture mitigated these deficits, whereas exercise or LBNP and cuffs partly mitigated them.
These data suggest that more direct, active sensorimotor-based countermeasures may be necessary to maintain preflight levels of functional performance after a long period of body unloading.
卧床休息可作为与太空飞行相关的身体卸载的地面模拟方式。在本研究中，我们确定了严格的头低位卧床休息如何影响受试者在功能测试（从坐到站、直线行走、行走转身、动态姿势描记）中的表现，这些测试用于挑战宇航员从太空返回后立即的平衡控制系统。
47名参与者在德国航空航天中心环境模拟设施进行30天6°头低位卧床休息前及休息后数小时接受评估。在这项名为SANS-CM的卧床休息研究中，参与者被分为4组，即：a）在30天内持续处于头低位；b）每天坐直6小时；c）每天接受6小时下体负压（LBNP）；或d）每天锻炼60分钟，然后佩戴静脉闭塞袖带6小时。
结果显示，严格的头低位卧床休息导致功能任务表现出现缺陷，这与宇航员太空飞行后观察到的情况相似。坐姿可减轻这些缺陷，而锻炼或下体负压及袖带可部分减轻这些缺陷。
这些数据表明，可能需要更直接、基于主动感觉运动的对策，以在长时间身体卸载后维持飞行前的功能表现水平。
