Can Treadmill Perturbations Evoke Stretch Reflexes in the Calf Muscles?
Can Treadmill Perturbations Evoke Stretch Reflexes in the Calf Muscles?
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DOI：
10.1371/journal.pone.0144815
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Harlaar J
中科院分区：
文献类型：
--
作者：
Sloot LH;van den Noort JC;van der Krogt MM;Bruijn SM;Harlaar J
反射去抑制是痉挛患者的一个问题，因为它限制了步态中运动功能的顺利和有效执行。跑步机腰带加速可能被用来测量行走过程中的反射，即通过背部弯曲脚踝和伸展小腿肌肉，而减速则表明在感觉反馈减少期间反射的调节。本研究的目的是检测在跑步机步行的站立阶段施加不同强度的腰带加速和减速是否能在健康受试者的腓肠肌、比目鱼肌和胫骨前肌引起反射。对10名受试者进行了肌肉肌电和关节运动学检测。为了确定是否发生拉伸反射，我们评估了模拟的肌腱长度和拉伸速度，肌肉活动量，以及肌肉活动的爆发或抑制的发生率及其时间延迟，以及激动者和拮抗者肌肉之间的共同收缩。虽然扰动对踝关节角度的影响很小，只有2.8±1.0°，但相对于未扰动的步行，扰动导致了肌肉长度和拉伸速度的明显变化。伸展肌肉表现出肌肉活动爆发的发生率增加，这发生在合理的电生理时间延迟(163-191ms)之后。它们的幅度与肌肉的拉伸速度有关，与拮抗肌的协同收缩无关。这些影响随着微扰强度的增大而增大。缩短的肌肉表现出相反的效果，小腿肌肉的肌肉活动受到抑制。扰动对时空参数的影响很小，表明正常行走得以保留。因此，我们的发现表明，跑步机的干扰可以唤起小腿肌肉和胫骨前肌的反射。这项综合性的研究可以为临床实施基于跑步机的临床步态分析中功能测量反射的跑步机扰动奠定基础。
Disinhibition of reflexes is a problem amongst spastic patients, for it limits a smooth and efficient execution of motor functions during gait. Treadmill belt accelerations may potentially be used to measure reflexes during walking, i.e. by dorsal flexing the ankle and stretching the calf muscles, while decelerations show the modulation of reflexes during a reduction of sensory feedback. The aim of the current study was to examine if belt accelerations and decelerations of different intensities applied during the stance phase of treadmill walking can evoke reflexes in the gastrocnemius, soleus and tibialis anterior in healthy subjects. Muscle electromyography and joint kinematics were measured in 10 subjects. To determine whether stretch reflexes occurred, we assessed modelled musculo-tendon length and stretch velocity, the amount of muscle activity, as well as the incidence of bursts or depressions in muscle activity with their time delays, and co-contraction between agonist and antagonist muscle. Although the effect on the ankle angle was small with 2.8±1.0°, the perturbations caused clear changes in muscle length and stretch velocity relative to unperturbed walking. Stretched muscles showed an increasing incidence of bursts in muscle activity, which occurred after a reasonable electrophysiological time delay (163–191 ms). Their amplitude was related to the muscle stretch velocity and not related to co-contraction of the antagonist muscle. These effects increased with perturbation intensity. Shortened muscles showed opposite effects, with a depression in muscle activity of the calf muscles. The perturbations only slightly affected the spatio-temporal parameters, indicating that normal walking was retained. Thus, our findings showed that treadmill perturbations can evoke reflexes in the calf muscles and tibialis anterior. This comprehensive study could form the basis for clinical implementation of treadmill perturbations to functionally measure reflexes during treadmill-based clinical gait analysis.