Department of Sport and Sport Science, University of Freiburg, Freiburg, Germany.
Praxisklinik Rennbahn AG, Muttenz, Switzerland.
Sci Rep. 2019 Jul 19;9(1):10490. doi: 10.1038/s41598-019-47091-x.
The control of bipedal stance and the capacity to regain postural equilibrium after its deterioration in variable gravities are crucial prerequisites for manned space missions. With an emphasize on natural orthograde posture, computational techniques synthesize muscle activation patterns of high complexity to a simple synergy organization. We used nonnegative matrix factorization to identify muscle synergies during postural recovery responses in human and to examine the functional significance of such synergies for hyper-gravity (1.75 g) and hypo-gravity (0.25 g). Electromyographic data were recorded from leg, trunk and arm muscles of five human exposed to five modes of anterior and posterior support surface translations during parabolic flights including transitional g-levels of 0.25, 1 and 1.75 g. Results showed that in 1 g four synergies accounted for 99% of the automatic postural response across all muscles and perturbation directions. Each synergy in 1 g was correlated to the corresponding one in 0.25 and 1.75 g. This study therefore emphasizes the similarity of the synergy organization of postural recovery responses in Earth, hypo- and hyper-gravity conditions, indicating that the muscle synergies and segmental strategies acquired under terrestrial habits are robust and persistent across variable and acute changes in gravity levels.
双足站立姿势的控制和在变重力环境中恶化后恢复姿势平衡的能力是载人航天任务的关键前提条件。在强调自然直立姿势的前提下，计算技术将高度复杂的肌肉激活模式综合为简单的协同组织。我们使用非负矩阵分解来识别人类在姿势恢复反应期间的肌肉协同作用，并研究这些协同作用对超重力（1.75g）和低重力（0.25g）的功能意义。在抛物线飞行中，我们记录了 5 名人类的腿部、躯干和手臂肌肉的肌电图数据，这些人经历了包括 0.25、1 和 1.75g 的过渡 g 水平在内的 5 种前后支撑面平移模式。结果表明，在 1g 时，四个协同作用解释了所有肌肉和扰动方向的自动姿势反应的 99%。在 1g 时，每个协同作用与 0.25 和 1.75g 时的相应协同作用相关。因此，这项研究强调了在地球、低重力和高重力条件下姿势恢复反应的协同组织的相似性，表明在地球习惯下获得的肌肉协同作用和节段策略在重力水平的变化和急性变化中是强大且持久的。
