Muscle synergies of multidirectional postural control in astronauts on Earth after a long-term stay in space
Muscle synergies of multidirectional postural control in astronauts on Earth after a long-term stay in space
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地球宇航员在太空长期停留后多向姿势控制的肌肉协同作用
DOI：
10.1152/jn.00232.2021
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发表时间：
2022
影响因子：
2.5
通讯作者：
Motoki Kouzaki
中科院分区：
文献类型：
--
作者：
Shota Hagio;Akihiko Ishihara;Masahiro Terada;Hiroko Tanabe;Benio Kibushi;Akira Higashibata;Shin Yamada;Satoshi Furukawa;Chiaki Mukai;Noriaki Ishioka;Motoki Kouzaki
人类生物系统的运动已经适应了地球上1克引力下的物理环境。然而，空间微重力对潜在的功能性神经肌肉控制行为的影响仍然知之甚少。在这里，我们的目的是阐明长期暴露在微重力环境中对多种肌肉活动的功能协调的影响。记录了5名在太空停留至少3mo的航天员在保持多向站立姿势时的16条小腿肌肉的活动情况。使用因式分解算法从肌肉激活数据集中估计肌肉组的协调激活模式，即肌肉协同作用。每个宇航员总共重复了五次实验，一次是在太空飞行之前，四次是在太空飞行之后。长期暴露于微重力环境后，肌肉协同作用的组成发生了变化，协同作用的数量保持不变，变化的程度与姿势摆动速度的增加有关。此外，与飞行前相比，回归后3个月提取的肌肉协同作用在激活曲线上相似，但在肌肉组成上不同。这些结果表明，在宇航员再次暴露在重力下后，神经肌肉系统中的模块结构发生了重组，以适应微重力环境，然后可能重新优化以适应新的感觉运动环境。随着重力的变化，肌肉协同效应有望被用作宇航员状态的生理标志。新与注意：人类神经肌肉系统已经适应了地球上的重力环境。在这里，我们证明了在空间中长期暴露在微重力环境中，改变了多个肌肉活动的功能协调，涉及到多方向站立姿势控制。此外，这种变化导致了在返回地球后立即进行姿势控制所需的更大的调节平衡活动，以及在太空飞行前和返回地球后3个月肌肉协调方面的差异。
Movements of the human biological system have adapted to the physical environment under the 1-g gravitational force on Earth. However, the effects of microgravity in space on the underlying functional neuromuscular control behaviors remain poorly understood. Here, we aimed to elucidate the effects of prolonged exposure to a microgravity environment on the functional coordination of multiple muscle activities. The activities of 16 lower limb muscles of 5 astronauts who stayed in space for at least 3 mo were recorded while they maintained multidirectional postural control during bipedal standing. The coordinated activation patterns of groups of muscles, i.e., muscle synergies, were estimated from the muscle activation datasets using a factorization algorithm. The experiments were repeated a total of five times for each astronaut, once before and four times after spaceflight. The compositions of muscle synergies were altered, with a constant number of synergies, after long-term exposure to microgravity, and the extent of the changes was correlated with the increased velocity of postural sway. Furthermore, the muscle synergies extracted 3 mo after the return were similar in their activation profile but not in their muscle composition compared with those extracted in the preflight condition. These results suggest that the modularity in the neuromuscular system became reorganized to adapt to the microgravity environment and then possibly reoptimized to the new sensorimotor environment after the astronauts were reexposed to a gravitational force. It is expected that muscle synergies can be used as physiological markers of the status of astronauts with gravity-dependent change.NEW & NOTEWORTHYThe human neuromuscular system has adapted to the gravitational environment on Earth. Here, we demonstrated that prolonged exposure to a microgravity environment in space changes the functional coordination of multiple muscle activities regarding multidirectional standing postural control. Furthermore, the amount of change led to a greater regulatory balancing activity needed for postural control immediately after returning to Earth and differences in muscular coordination before space flight and 3 mo after the return to Earth.