School of Health Sciences, University of Salford, Salford, Manchester, M6 6PU, UK.
Gait Posture. 2021 Jan;83:250-255. doi: 10.1016/j.gaitpost.2020.10.021. Epub 2020 Oct 22.
The head, arms and trunk segment constitute a large proportion of the body's mass. Therefore, small alterations in trunk inclination may affect lower limb joint moments and muscle activation patterns. Although previous research has investigated the effect of changing frontal plane inclination of the trunk, it is not clear how increasing trunk flexion will impact on the activation of the lower limb muscles.
What is the effect of independently manipulating trunk flexion angle on lower limb kinematics, moments and muscle function?
Gait analysis was carried out on 20 healthy people under four trunk flexion conditions: normal walking (NW), NW-5°, NW+5° and NW+10°. For the latter three conditions, a biofeedback approach was used to tightly control trunk flexion angle. A linear mixed model was used to investigate the effect of changing trunk flexion on joint angles, moments, and knee muscle activation.
There were clear increases in hip and ankle moments as trunk flexion was increased, but no change in knee moments. The results also showed a linear increase in knee flexor muscle activity and a corresponding increase in co-contraction as trunk flexion increased. Interestingly, there was a dramatic change in the profile of hamstring activity. In the medial hamstrings, this change led to a 100% increase in activation during early stance as flexion was increased by 5° from NW.
This is the first study to demonstrate a strong dependence of knee flexor muscle activity on trunk flexion. This is important as people with knee osteoarthritis have been observed to walk with elevated muscle activation and this has been linked to increased joint loads. It is possible that these altered muscle patterns may result from increased trunk flexion during walking.
头部、手臂和躯干部分构成了身体质量的很大一部分。因此，躯干倾斜的微小变化可能会影响下肢关节力矩和肌肉激活模式。尽管先前的研究已经调查了改变躯干额状面倾斜度的影响，但尚不清楚增加躯干屈曲度将如何影响下肢肌肉的激活。
独立操纵躯干屈曲角度如何影响下肢运动学、力矩和肌肉功能？
在 20 名健康人中进行步态分析，在四种躯干屈曲条件下：正常行走（NW）、NW-5°、NW+5°和 NW+10°。对于后三种情况，采用生物反馈方法来严格控制躯干屈曲角度。使用线性混合模型来研究改变躯干屈曲对关节角度、力矩和膝关节肌肉激活的影响。
随着躯干屈曲的增加，髋关节和踝关节力矩明显增加，但膝关节力矩没有变化。结果还表明，随着躯干屈曲的增加，膝关节屈肌的活性呈线性增加，协同收缩也相应增加。有趣的是，腘绳肌活动的模式发生了显著变化。在内侧腘绳肌中，这种变化导致在从 NW 增加 5°的情况下，早期站立时的激活度增加了 100%。
这是第一项表明膝关节屈肌活性强烈依赖于躯干屈曲的研究。这很重要，因为已经观察到膝骨关节炎患者在行走时肌肉激活度升高，并且这与关节负荷增加有关。可能是这些改变的肌肉模式可能是由于行走时躯干屈曲增加所致。
