Effects of physical training on central regulation for cardiovascular system during exercise

心血管系统在运动中起着重要的作用，为运动中的骨骼肌提供氧气。中枢神经控制和外周反射被认为是运动时心血管温度调节的主要控制系统。本研究的目的是揭示运动训练是否对心血管系统的中枢神经控制有影响。1在握力运动中测量肌肉交感神经活动（MSNA），并比较优势臂运动和非优势臂运动之间的MSNA。优势臂的MSNA增加幅度大于非优势臂，这可能是由于日常生活中经常使用优势臂产生类似训练效应的结果。4周非优势前臂训练后，训练臂在握力过程中MSNA的增加更大，而对照臂的变化不明显。2在肌肉收缩开始前后同时测量活动骨骼肌的肌血流量（MBF）和MSNA。就在收缩MSNA抑制和MBF趋于增加。运动开始后，MSNA的增加延迟了几秒钟，而MBF突然增加。收缩前MSNA抑制可能受中枢因素控制，在肌肉收缩前产生降低肌肉血管张力的作用。3比较前臂肌肉训练前后最大握力运动时心率（HR）的升高。训练后，训练组心率上升幅度较大，而非训练组心率无明显变化。由于心率的上升主要受中枢指令控制，这可以解释肌肉训练会改变心脏的中枢调节。这些结果证实了中枢因素即中枢指令对运动中心血管调节的强烈影响。运动训练可以改变这种控制系统。

Cardiovascular system is an important role to supply oxygen to active skeletal muscle during physical exercise. Central neural control and peripheral reflex are considered as main control system in regulation of cardiovascurature during exercise. Aim of this project was to reveal whether or not physical training has an effect on the central neural control of cardiovascular system.1 Muscle sympathetic nerve activity (MSNA) was measured during handgrip exercise and compared it between the dominant and the non-dominant arm exercise. The increased MSNA was greater in the dominant than in the non-dominant arm. This may be resulted from that frequent use in dominant arm in daily life as like training effect. After 4 weeks non-dominant forearm training, an increased MSNA during handgrip was greater in trained arm and insignificant changes in control arm.2 Muscle blood flow (MBF) in the active skeletal muscle and MSNA were measured simultaneously before and after onset of muscle contraction. Just before the contraction MSNA suppressed and MBF tended to increase. After onset of exercise MSNA increase was delayed in several seconds, while MBF increased abruptly. MSNA suppression before the contraction may be controlled by central factor, which should produce to decrease muscle vascular tone before muscle contraction.3 Heart rate (HR) rose during maximal handgrip exercise was compared between before and after forearm muscle training. After the training HR rise was greater in the trained arm whereas no significant change in non-trained arm. Since initial increase in HR was controlled primarily by central command, it could explain that centrally regulation of the heart would be modified with muscular training.These results confirm that centrally factor i.e. central command may effect strongly on cardiovascular regulation during exercise, and exercise training could modify this control system.