Action observation (AO) and motor imagery (MI) are potential methods to improve various motor functions. AO and MI facilitate corticospinal excitability. Additionally, the combination of AO and MI (AO + MI) facilitates greater corticospinal excitability than AO alone. However, it is unclear whether AO + MI facilitates the excitability of spinal motor neurons better than AO alone. Thus, in this study, we compared the excitability of spinal motor neurons between AO + MI and AO conditions using F-waves. We recruited healthy adult volunteers (n = 31) for F-wave analysis. We recorded F-waves during relaxation to determine the baseline level (Rest), followed by measurement during AO and AO + MI. To counterbalance the order effect, 15 participants performed AO first, while the others performed AO + MI first. F-wave persistence was significantly increased during AO and AO + MI compared to Rest. The F-wave/M-wave amplitude ratio was significantly increased during AO + MI compared to Rest. The present results suggest that the combination of AO and MI facilitates the excitability of spinal motor neurons compared to Rest, whereas AO alone does not.

动作观察（AO）和运动图像（MI）是改善各种运动功能的潜在方法。AO和MI促进皮质脊髓兴奋性。另外，与单独的AO相比，AO和MI的组合（AO + MI）促进了更大的皮质脊髓兴奋性。但是，尚不清楚AO + MI是否比单独使用AO更好地促进脊髓运动神经元的兴奋性。因此，在这项研究中，我们使用F波比较了AO + MI和AO条件之间的脊髓运动神经元的兴奋性。我们招募了健康的成年人志愿者（n = 31）进行F波分析。我们记录了松弛过程中的F波以确定基线水平（Rest），然后在AO和AO + MI中进行测量。为了平衡顺序效应，有15位参与者首先执行AO，而其他参与者则首先执行AO + MI。与Rest相比，AO和AO + MI期间的F波持续性显着增加。与Rest相比，在AO + MI期间，F波/ M波振幅比显着增加。目前的结果表明，与Rest相比，AO和MI的组合促进了脊髓运动神经元的兴奋性，而单独使用AO则没有。