Cognition, Action and Sensorimotor Plasticity [CAPS], INSERM U-1093, University of Bourgogne Franche-Comté-UFR STAPS, BP 27877, 21078, Dijon Cedex, France.
Cognition, Action and Sensorimotor Plasticity [CAPS], INSERM U-1093, Université de Bourgogne-UFR STAPS, BP 27877, 21078, Dijon Cedex, France.
Eur J Appl Physiol. 2021 Aug;121(8):2337-2348. doi: 10.1007/s00421-021-04710-8. Epub 2021 May 17.
Cross education defines the gains observed in the contralateral limb following unilateral strength training of the other limb. The present study questioned the neural mechanisms associated with cross education following training by motor imagery (MI) or submaximal neuromuscular electrical stimulation (NMES), both representing a partial activation of the motor system as compared to conventional strength training.
Twenty-seven participants were distributed in three groups: MI, NMES and control. Training groups underwent a training program of ten sessions in two weeks targeting plantar flexor muscles of one limb. In both legs, neuromuscular plasticity was assessed through maximal voluntary isometric contraction (MViC) and triceps surae electrophysiological responses evoked by electrical nerve stimulation (H-reflexes and V-waves).
NMES and MI training improved MViC torque of the trained limb by 11.3% (P < 0.001) and 13.8% (P < 0.001), respectively. MViC of the untrained limb increased by 10.3% (P < 0.003) in the MI group only, accompanied with increases in V-waves on both sides. In the NMES group, V-waves only increased in the trained limb. In the MI group, rest H-reflexes increased in both the trained and the untrained triceps suraes.
MI seems to be effective to induce cross education, probably because of the activation of cortical motor regions that impact the corticospinal neural drive of both trained and untrained sides. Conversely, submaximal NMES did not lead to cross education. The present results emphasize that cross education does not necessarily require muscle activity of the trained limb.
交叉教育是指在对另一侧肢体进行单侧力量训练后，对另一侧肢体观察到的收益。本研究通过运动想象（MI）或亚最大神经肌肉电刺激（NMES）来质疑与交叉教育相关的神经机制，与传统力量训练相比，这两种方法都代表了运动系统的部分激活。
27 名参与者被分为三组：MI、NMES 和对照组。训练组在两周内进行了十次针对一条肢体跖屈肌的训练计划。在两条腿上，通过最大随意等长收缩（MViC）和电神经刺激诱发的比目鱼肌电生理反应（H 反射和 V 波）评估神经肌肉可塑性。
NMES 和 MI 训练分别使训练侧的 MViC 扭矩提高了 11.3%（P<0.001）和 13.8%（P<0.001）。仅在 MI 组中，未训练侧的 MViC 增加了 10.3%（P<0.003），同时两侧的 V 波均增加。在 NMES 组中，仅在训练侧 V 波增加。在 MI 组中，训练和未训练的比目鱼肌的静息 H 反射均增加。
MI 似乎能有效地诱导交叉教育，可能是因为激活了皮质运动区，从而影响了训练和未训练侧的皮质脊髓神经驱动。相反，亚最大 NMES 并未导致交叉教育。本研究结果强调，交叉教育不一定需要训练侧的肌肉活动。
