Aagaard Per, Simonsen Erik B, Andersen Jesper L, Magnusson Peter, Dyhre-Poulsen Poul
Department of Neurophysiology, Institute of Medical Physiology, Denmark.
J Appl Physiol (1985). 2002 Jun;92(6):2309-18. doi: 10.1152/japplphysiol.01185.2001.
Combined V-wave and Hoffmann (H) reflex measurements were performed during maximal muscle contraction to examine the neural adaptation mechanisms induced by resistance training. The H-reflex can be used to assess the excitability of spinal alpha-motoneurons, while also reflecting transmission efficiency (i.e., presynaptic inhibition) in Ia afferent synapses. Furthermore, the V-wave reflects the overall magnitude of efferent motor output from the alpha-motoneuron pool because of activation from descending central pathways. Fourteen male subjects participated in 14 wk of resistance training that involved heavy weight-lifting exercises for the muscles of the leg. Evoked V-wave, H-reflex, and maximal M-wave (M(max)) responses were recorded before and after training in the soleus muscle during maximal isometric ramp contractions. Maximal isometric, concentric, and eccentric muscle strength was measured by use of isokinetic dynamometry. V-wave amplitude increased approximately 50% with training (P < 0.01) from 3.19 +/- 0.43 to 4.86 +/- 0.43 mV, or from 0.308 +/- 0.048 to 0.478 +/- 0.034 when expressed relative to M(max) (+/- SE). H-reflex amplitude increased approximately 20% (P < 0.05) from 5.37 +/- 0.41 to 6.24 +/- 0.49 mV, or from 0.514 +/- 0.032 to 0.609 +/- 0.025 when normalized to M(max). In contrast, resting H-reflex amplitude remained unchanged with training (0.503 +/- 0.059 vs. 0.499 +/- 0.063). Likewise, no change occurred in M(max) (10.78 +/- 0.86 vs. 10.21 +/- 0.66 mV). Maximal muscle strength increased 23-30% (P < 0.05). In conclusion, increases in evoked V-wave and H-reflex responses were observed during maximal muscle contraction after resistance training. Collectively, the present data suggest that the increase in motoneuronal output induced by resistance training may comprise both supraspinal and spinal adaptation mechanisms (i.e., increased central motor drive, elevated motoneuron excitability, reduced presynaptic inhibition).
在最大肌肉收缩期间进行V波和霍夫曼（H）反射联合测量，以研究抗阻训练诱导的神经适应机制。H反射可用于评估脊髓α运动神经元的兴奋性，同时也反映Ia传入突触的传递效率（即突触前抑制）。此外，V波反映了由于下行中枢通路激活而从α运动神经元池传出的运动输出的总体大小。14名男性受试者参加了为期14周的抗阻训练，其中包括对腿部肌肉进行大重量举重练习。在最大等长斜坡收缩期间，在比目鱼肌训练前后记录诱发的V波、H反射和最大M波（M(max)）反应。使用等速测力计测量最大等长、向心和离心肌肉力量。训练后V波振幅增加约50%（P<0.01），从3.19±0.43mV增加到4.86±0.43mV，或相对于M(max)（±SE）表示时从0.308±0.048增加到0.478±0.034。H反射振幅增加约20%（P<0.05），从5.37±0.41mV增加到6.24±0.49mV，或归一化到M(max)时从0.514±0.032增加到0.609±0.025。相比之下，静息H反射振幅在训练后保持不变（0.503±0.059对0.499±0.063）。同样，M(max)也没有变化（10.78±0.86对10.21±0.66mV）。最大肌肉力量增加23 - 30%（P<0.05）。总之，在抗阻训练后的最大肌肉收缩期间观察到诱发的V波和H反射反应增加。总体而言，目前的数据表明，抗阻训练诱导的运动神经元输出增加可能包括脊髓上和脊髓适应机制（即增加的中枢运动驱动、提高的运动神经元兴奋性、减少的突触前抑制）。
