Gong Yikang, Cheng Zhenghan, Teo Ee-Chon, Gu Yaodong
Faculty of Sports Science, Ningbo University, Ningbo 315211, China.
Research Academy of Grand Health, Ningbo University, Ningbo 315211, China.
Bioengineering (Basel). 2024 Jun 27;11(7):655. doi: 10.3390/bioengineering11070655.
To determine the impact of active muscle on the dynamic response of a pilot's neck during simulated emergency ejection, a detailed three-dimensional (3D) cervical spine (C0-T1) finite element (FE) model integrated with active muscles was constructed. Based on the Hill-type model characterising the muscle force activation mechanics, 13 major neck muscles were modelled. The active force generated by each muscle was simulated as functions of (i) active state (Na), (ii) velocity (Fv(v)), and (iii) length (FL(L)). An acceleration-time profile with an initial acceleration rate of 125 G·s in the 0-80 ms period, reaching peak acceleration of 10 G, then kept constant for a further 70 ms, was applied. The rotational angles of each cervical segment under these ejection conditions were compared with those without muscles and with passive muscles derived from the previous study. Similar trends of segmental rotation were observed with S- and C-curvature of the cervical spine in the 150 ms span analysed. With active muscles, the flexion motion of the C0-C2 segments exhibited higher magnitudes of rotation compared to those without muscle and passive muscle models. The flexion motion increased rapidly and peaked at about 95-105 ms, then decreased rapidly to a lower magnitude. Lower C2-T1 segments exhibited less variation in flexion and extension motions. Overall, during emergency ejections, active muscle activities effectively reduce the variability in rotational angles across cervical segments, except C0-C2 segments in the 60-120 ms period. The role of the active state dynamics of the muscles was crucial to the magnitude of the muscle forces demonstrated. This indicates that it is crucial for pilots to consciously contract their muscles before ejection to prevent cervical spine injuries.
为了确定在模拟紧急弹射过程中主动肌肉对飞行员颈部动态响应的影响，构建了一个详细的三维（3D）颈椎（C0-T1）有限元（FE）模型，并集成了主动肌肉。基于表征肌肉力激活机制的希尔型模型，对13块主要颈部肌肉进行了建模。每块肌肉产生的主动力被模拟为以下因素的函数：（i）激活状态（Na）、（ii）速度（Fv(v)）和（iii）长度（FL(L)）。应用了一个加速度-时间曲线，在0-80毫秒期间初始加速度率为125 G·s，达到10 G的峰值加速度，然后在接下来的70毫秒内保持恒定。将这些弹射条件下每个颈椎节段的旋转角度与之前研究中无肌肉和被动肌肉情况下的旋转角度进行了比较。在分析的150毫秒跨度内，观察到颈椎S形和C形弯曲时节段旋转的相似趋势。与无肌肉和被动肌肉模型相比，有主动肌肉时，C0-C2节段的屈曲运动表现出更大的旋转幅度。屈曲运动迅速增加，并在约95-105毫秒达到峰值，然后迅速下降到较低幅度。较低的C2-T1节段在屈伸运动中的变化较小。总体而言，在紧急弹射过程中，主动肌肉活动有效地减少了颈椎节段旋转角度的变异性，但在60-120毫秒期间C0-C2节段除外。肌肉激活状态动力学的作用对于所展示的肌肉力大小至关重要。这表明飞行员在弹射前有意识地收缩肌肉以预防颈椎损伤至关重要。
