Programa de Magister en Kinesiología y Biomecánica Clínica, Departamento de Kinesiología, Universidad Metropolitana de Ciencias de la Educación, Santiago, Chile.
Department of Physical Therapy, Faculty of Medicine, University of Chile, Santiago, Chile.
Eur J Appl Physiol. 2017 Dec;117(12):2469-2477. doi: 10.1007/s00421-017-3734-6. Epub 2017 Oct 10.
The purpose of this study was to investigate the importance of cutaneous feedback on neural activation during maximal voluntary contraction (MVC) of the ankle plantar flexors.
The effects of cutaneous plantar anaesthesia were assessed in 15 subjects and compared to 15 controls, using a one-day pre/post-repeated measures design. Cutaneous plantar anaesthesia was induced by lidocaine injection at the centre of forefoot, lateral midfoot, and heel. Each subject performed isometric MVCs of the ankle plantar flexors. During each isometric ramp contraction, the following variables were assessed: maximal isometric torque; surface electromyography (EMG) activity of the medial gastrocnemius (MG) and tibialis anterior (TA) muscles; and co-contraction index (CCI) between the MG and TA.
For ankle torque, two-way ANOVA showed no significant interaction between the pre/post-measurements × group (p = 0.166). However, MG activity presented significant interactions between the pre/post-measurements × group (p = 0.014). Post hoc comparisons indicated a decrease of MG activity in the experimental group, from 85.9 ± 11.9 to 62.7 ± 30.8% (p = 0.016). Additionally, the post-anaesthesia MG activity of the experimental group differed statistically with pre- and post-MG activity of the control group (p = 0.027 and p = 0.008, respectively). For TA activity and CCI, two-way ANOVA detected no significant interactions between the pre/post-measurements × group (p = 0.605 and p = 0.332, respectively).
Our results indicate that during MVC, cutaneous feedback modulates neural activity to MG muscle, without changing the extent of MG-TA co-contraction.
本研究旨在探讨在踝关节跖屈肌最大自主收缩（MVC）过程中，皮肤反馈对神经激活的重要性。
采用一天一次的预/后重复测量设计，评估 15 名受试者和 15 名对照者的足底皮区麻醉的影响。通过在前脚、中足外侧和足跟中心注射利多卡因诱导足底皮区麻醉。每位受试者进行踝关节跖屈肌等长 MVC。在每次等速 ramp 收缩过程中，评估以下变量：最大等长扭矩；内侧腓肠肌（MG）和胫骨前肌（TA）的表面肌电图（EMG）活动；以及 MG 和 TA 之间的共同收缩指数（CCI）。
对于踝关节扭矩，双因素方差分析显示，预/后测量与组之间没有显著的交互作用（p=0.166）。然而，MG 活动表现出预/后测量与组之间的显著交互作用（p=0.014）。事后比较表明，实验组的 MG 活动从 85.9±11.9%下降到 62.7±30.8%（p=0.016）。此外，实验组的麻醉后 MG 活动与对照组的预和 post-MG 活动有统计学差异（p=0.027 和 p=0.008）。对于 TA 活动和 CCI，双因素方差分析未检测到预/后测量与组之间的显著交互作用（p=0.605 和 p=0.332）。
我们的结果表明，在 MVC 期间，皮肤反馈调节 MG 肌肉的神经活动，而不会改变 MG-TA 共同收缩的程度。
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