Aerospace Medicine and Rehabilitation Laboratory, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, United Kingdom.
Harvard Medical School, Department of Neurology, Beth Israel Deaconess Medical Center Boston, Massachusetts, United States.
Life Sci Space Res (Amst). 2022 Aug;34:68-86. doi: 10.1016/j.lssr.2022.06.007. Epub 2022 Jul 29.
Space agencies are planning to send humans back to the Lunar surface, in preparation for crewed exploration of Mars. However, the effect of hypogravity on human skeletal muscle is largely unknown. A recently established rodent partial weight-bearing model has been employed to mimic various levels of hypogravity loading and may provide valuable insights to better understanding how human muscle might respond to this environment. The aim of this study was to perform a systematic review regarding the effects of partial weight-bearing on the morphology and function of rodent skeletal muscle. Five online databases were searched with the following inclusion criteria: population (rodents), intervention (partial weight-bearing for ≥1 week), control (full weight-bearing), outcome(s) (skeletal muscle morphology/function), and study design (animal intervention). Of the 2,993 studies identified, eight were included. Partial weight-bearing at 20%, 40%, and 70% of full loading caused rapid deconditioning of skeletal muscle morphology and function within the first one to two weeks of exposure. Calf circumference, hindlimb wet muscle mass, myofiber cross-sectional area, front/rear paw grip force, and nerve-stimulated plantarflexion force were reduced typically by medium to very large effects. Higher levels of partial weight-bearing often attenuated deconditioning but failed to entirely prevent it. Species and sex mediated the deconditioning response. Risk of bias was low/unclear for most studies. These findings suggest that there is insufficient stimulus to mitigate muscular deconditioning in hypogravity settings highlighting the need to develop countermeasures for maintaining astronaut/cosmonaut muscular health on the Moon and Mars.
航天局计划将人类送回月球表面，为载人探索火星做准备。然而，微重力对人类骨骼肌的影响在很大程度上是未知的。最近建立的啮齿动物部分负重模型被用来模拟各种程度的微重力负荷，可能为更好地理解人类肌肉可能对这种环境的反应提供有价值的见解。本研究的目的是对部分负重对啮齿动物骨骼肌形态和功能的影响进行系统评价。使用以下纳入标准对五个在线数据库进行了搜索：人群（啮齿动物）、干预（≥1 周的部分负重）、对照（完全负重）、结果（骨骼肌形态/功能）和研究设计（动物干预）。在确定的 2993 项研究中，有 8 项被纳入。在最初的一到两周内，20%、40%和 70%的部分负重导致骨骼肌形态和功能迅速去适应。小腿周长、后肢湿重、肌纤维横截面积、前/后爪握力和神经刺激跖屈力通常会减少中等至非常大的影响。更高水平的部分负重往往会减轻去适应，但不能完全预防。物种和性别调节去适应反应。大多数研究的偏倚风险较低/不明确。这些发现表明，在微重力环境下，刺激不足以减轻肌肉去适应，这凸显了开发在月球和火星上维持宇航员/航天员肌肉健康的对策的必要性。
