Barrué-Belou Simon, Amarantini David, Marque Philippe, Duclay Julien
Toulouse NeuroImaging Center, Université de Toulouse, Inserm, UPS, Toulouse, France.
Service de Médecine Physique et Réadaptation, CHU Toulouse Rangueil, Avenue du Pr Jean Poulhès, 31059, Toulouse, France.
Eur J Appl Physiol. 2016 May;116(5):1021-30. doi: 10.1007/s00421-016-3367-1. Epub 2016 Mar 30.
This study investigated the neural adaptations following submaximal isokinetic eccentric strength training of the plantar flexors. The modulation of electromyographic (EMG) activity and spinal excitability were compared in the soleus muscle (SOL) during isometric, concentric and eccentric maximal voluntary contractions (MVC) before and after submaximal isokinetic eccentric training.
Eighteen healthy subjects were divided into a training group (n = 8) and a control group (n = 10). The training protocol consisted of sixteen sessions of isokinetic eccentric strength training during 8 weeks. Normalized EMG was used to assess the activity of SOL and medial gastrocnemius muscle (MG). For SOL, maximal Hoffmann reflex (H-reflex) and compound motor potential were evoked during isometric, concentric and eccentric actions at rest (Hmax and Mmax, respectively) and during MVC (Hsup and Msup, respectively).
The results showed that the torque and normalized EMG of SOL significantly increased after training during eccentric (+20.5 and +28.8 %, respectively) and isometric (+18.2 and +23.0 %, respectively) MVC (p < 0.05). Hmax/Mmax and Hsup/Msup ratios were not significantly modified after training for SOL (p > 0.05), and remained significantly depressed during eccentric compared to isometric and concentric actions (p < 0.05). In contrast, no significant difference was observed on normalized EMG of MG (p > 0.05).
These results suggested that the increase in voluntary torque after submaximal isokinetic eccentric training can be at least partly ascribed to enhanced neural drive for SOL that does not affect the H-reflex pathway.
本研究调查了跖屈肌次最大等速离心力量训练后的神经适应性。在次最大等速离心训练前后，比较了比目鱼肌（SOL）在等长、向心和离心最大自主收缩（MVC）过程中肌电图（EMG）活动和脊髓兴奋性的调节情况。
18名健康受试者被分为训练组（n = 8）和对照组（n = 10）。训练方案包括在8周内进行16次等速离心力量训练。使用标准化EMG评估SOL和内侧腓肠肌（MG）的活动。对于SOL，在静息状态下的等长、向心和离心动作（分别为Hmax和Mmax）以及MVC过程中（分别为Hsup和Msup）诱发最大霍夫曼反射（H反射）和复合运动电位。
结果显示，训练后，SOL在离心（分别增加20.5%和28.8%）和等长（分别增加18.2%和23.0%）MVC过程中的扭矩和标准化EMG显著增加（p < 0.05）。训练后，SOL的Hmax/Mmax和Hsup/Msup比值没有显著改变（p > 0.05），与等长和向心动作相比，在离心过程中仍显著降低（p < 0.05）。相比之下，MG的标准化EMG没有观察到显著差异（p > 0.05）。
这些结果表明，次最大等速离心训练后自愿扭矩的增加至少部分归因于SOL神经驱动的增强，且不影响H反射通路。
