Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 100191, China.
College of Bioengineering, Chongqing University, Chongqing 400044, China.
J Healthc Eng. 2018 Apr 3;2018:8487308. doi: 10.1155/2018/8487308. eCollection 2018.
Long exposure to the microgravity will lead to muscle atrophy and bone loss. Treadmill exercise could mitigate the musculoskeletal decline. But muscle atrophy remains inevitable. The constraint loading applied on astronauts could affect the muscle force and its atrophy severity. However, the quantitative correlation between constraint loading mode and muscle forces remains unclear. This study aimed to characterize the influence of constraint loading mode on the lower limb muscle forces in weightless treadmill exercise. The muscle forces in the full gait cycle were calculated with the inverse dynamic model of human musculoskeletal system. The calculated muscle forces at gravity were validated with the EMG data. Muscle forces increased at weightlessness compared with those at the earth's gravity. The increasing percentage from high to low is as follows: biceps femoris, gastrocnemius, soleus, vastus, and rectus femoris, which was in agreement with the muscle atrophy observed in astronauts. The constraint loading mode had an impact on the muscle forces in treadmill exercise and thus could be manipulated to enhance the effect of the muscle training in spaceflight. The findings could provide biomechanical basis for the optimization of treadmill constraint system and training program and improve the countermeasure efficiency in spaceflight.
长期暴露于微重力会导致肌肉萎缩和骨丢失。跑步机运动可以减轻肌肉骨骼的衰退。但肌肉萎缩仍然不可避免。约束加载对宇航员施加的力会影响肌肉力量及其萎缩的严重程度。然而，约束加载模式与肌肉力量之间的定量相关性尚不清楚。本研究旨在描述约束加载模式对无重力跑步机运动中下肢肌肉力量的影响。使用人体肌肉骨骼系统的反向动力学模型计算了整个步态周期中的肌肉力量。使用肌电图数据验证了在重力下计算出的肌肉力量。与在地球重力下相比，无重力下的肌肉力量增加。从高到低的增加百分比如下：股二头肌、比目鱼肌、腓肠肌、股四头肌和股直肌，这与宇航员观察到的肌肉萎缩一致。约束加载模式对跑步机运动中的肌肉力量有影响，因此可以对其进行操纵，以增强在太空飞行中的肌肉训练效果。这些发现可以为跑步机约束系统和训练计划的优化提供生物力学基础，并提高太空飞行中的对策效率。
