Purpose

To compare the responses in knee joint muscle activation patterns to different perturbations during gait in healthy subjects.

Scope

Nine healthy participants were subjected to perturbed walking on a split-belt treadmill. Four perturbation types were applied, each at five intensities. The activations of seven muscles surrounding the knee were measured using surface EMG. The responses in muscle activation were expressed by calculating mean, peak, co-contraction (CCI) and perturbation responses (PR) values. PR captures the responses relative to unperturbed gait. Statistical parametric mapping analysis was used to compare the muscle activation patterns between conditions.

Results

Perturbations evoked only small responses in muscle activation, though higher perturbation intensities yielded a higher mean activation in five muscles, as well as higher PR. Different types of perturbation led to different responses in the rectus femoris, medial gastrocnemius and lateral gastrocnemius. The participants had lower CCI just before perturbation compared to the same phase of unperturbed gait.

Conclusions

Healthy participants respond to different perturbations during gait with small adaptations in their knee joint muscle activation patterns. This study provides insights in how the muscles are activated to stabilize the knee when challenged. Furthermore it could guide future studies in determining aberrant muscle activation in patients with knee disorders.

中文翻译：

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健康受试者步态过程中膝关节肌肉激活模式对不同扰动的反应

目的

比较健康受试者在步态过程中膝关节肌肉激活模式对不同扰动的反应。

范围

九名健康参与者在分带式跑步机上进行扰动行走。应用了四种扰动类型，每种类型有五种强度。使用表面肌电图测量膝关节周围七块肌肉的激活。通过计算平均值、峰值、协同收缩 (CCI) 和扰动响应 (PR) 值来表示肌肉激活的响应。PR 捕获相对于未受干扰步态的响应。统计参数映射分析用于比较条件之间的肌肉激活模式。

结果

扰动仅引起肌肉激活的小反应，但较高的扰动强度会在五块肌肉中产生更高的平均激活，以及更高的 PR。不同类型的扰动导致股直肌、腓肠肌内侧和腓肠外侧肌的不同反应。与未受干扰步态的同一阶段相比，参与者在干扰前的 CCI 较低。

结论

健康的参与者在步态过程中对不同的扰动做出反应，膝关节肌肉激活模式有很小的适应。这项研究提供了有关肌肉在受到挑战时如何被激活以稳定膝盖的见解。此外，它可以指导未来的研究，以确定膝关节疾病患者的异常肌肉激活。