Samii A, Wassermann E M, Ikoma K, Mercuri B, Hallett M
Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-1428, USA.
Neurology. 1996 May;46(5):1376-82. doi: 10.1212/wnl.46.5.1376.
We studied the effects of exercise on motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES). Subjects performed 30-second periods of isometric exercise of the extensor carpi radialis until fatigue, which was defined as the inability to maintain half maximum force. The amplitude of MEPs to TMS recorded from the resting muscle after each exercise period was on average more than twice the pre-exercise value (postexercise MEP facilitation). After fatigue occurred, the MEP amplitudes were approximately 60% of the pre-exercise value (postexercise MEP depression). There was a gradual recovery of the depressed MEPs to pre-exercise values over several minutes of rest. Postexercise MEP facilitation was constant when exercise intensity ranged from 10 to 50% of maximum voluntary contraction and it decayed to baseline over several minutes after the end of exercise. There was no postexercise MEP facilitation to TES. We hypothesize that both postexercise MEP facilitation and MEP depression are due to intracortical mechanisms.
我们研究了运动对经颅磁刺激（TMS）和经颅电刺激（TES）所诱发的运动诱发电位（MEP）的影响。受试者进行桡侧腕伸肌等长运动，持续30秒直至疲劳，疲劳定义为无法维持最大力量的一半。每个运动周期后，从静息肌肉记录的TMS诱发MEP的幅度平均比运动前的值高出两倍多（运动后MEP易化）。疲劳出现后，MEP幅度约为运动前值的60%（运动后MEP抑制）。在休息几分钟后，受抑制的MEP逐渐恢复到运动前的值。当运动强度在最大自主收缩的10%至50%范围内时，运动后MEP易化保持恒定，并在运动结束后几分钟内衰减至基线。TES不存在运动后MEP易化。我们推测运动后MEP易化和MEP抑制均归因于皮质内机制。
