Effects of physical training and detraining on sympathetic neural regulation of cardiovascular system

众所周知，体育训练可以改善心血管调节，但尚不清楚运动训练后改善的调节持续多久。本研究旨在探讨运动中心血管调节的重要环节交感神经活动（MSNA）对运动训练和停训的适应性变化。健康志愿者进行为期四周的高强度握力训练。采用显微神经电图技术，记录了疲劳性静态握力运动和运动后前臂咬合（PEFO）时胫神经的MSNA。MSNA增加的持续时间的握力运动时间，并达到最高水平的疲劳发作。在PEFO期间，MSNA反应大于在静息、运动前对照水平中观察到的。与训练前相比，训练后疲劳发作时的MSNA反应增加，而对PEFO的MSNA反应在训练后没有变化。4周停训后，与训练后即刻相比，疲劳发作时的MSNA反应降低，停训反应的幅度保持不变，长达一年。MSNA对PEFO的反应在训练中没有变化。总之，虽然中央命令和肌肉反射的因素，可以提高MSNA在肌肉收缩，肌肉代谢反射诱导的增加MSNA响应PEFO不调制的阻力训练。另一方面，阻力训练增加了中央指挥，这种效果增强了MSNA反应短暂。

It is well known that physical training improves cardiovascular regulation but it is not clear how long the improved regulation persists after exercise training. This project attempted to investigate the adaptive change in sympathetic nervous activity (MSNA), which plays an important role in the control of cardiovascular regulation during exercise, to exercise training and detraining. Healthy volunteers performed high intensity handgrip exercise training for four weeks. MSNA was recorded from the tibial nerve by a microneurography technique during fatiguing static handgrip exercise and following post-exercise forearm occlusion (PEFO).Findings :1. MSNA increased in relation to the duration of handgrip exercise time and reached its maximal level at the onset of fatigue. During PEFO the MSNA response was greater than observed in the resting, pre-exercise control level.2. The MSNA response at the onset of fatigue was increased post-training compared to pre-training, while the MSNA response to PEFO was unchanged post-training.3. After four weeks detraining, the MSNA response at the onset of fatigue decreased compared to the immediate post-training and responses and the magnitude of the detraining responses remained unchanged for up to one year The MSNA response to PEFO was unchanged by training. In conclusion, although central command and muscle reflex are factors that can enhance MSNA during muscle contraction, the muscle metaboreflex-induced increase in the MSNA response to PEFO was not modulated by resistance training. On the other hand, resistance training increased central command and this effect enhanced the MSNA response transiently.