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目的探讨推拉动作对脑血管循环功能的影响及推拉效应的＋ Ｇｚ 下降机制。方法１０ 名被试者在旋转床上经受“直立位（ ＋ １Ｇｚ） － 倒立位（ － １Ｇｚ） － 直立位（ ＋ １Ｇｚ）”的模拟推拉动作，采用经颅多谱勒（ＴＣＤ） 技术监测分析旋转床模拟推拉动作过程中脑血流速度及脉动参数的变化。结果倒立位（ － １Ｇｚ）时出现收缩期流速（Ｖｓ） 增加、舒张期流速（Ｖｄ） 降低、脉动参数（ＰＩ） 与（ＲＩ） 升高的阻力增高型频谱，随后直立位（ ＋ １ Ｇｚ） 时，这些变化更加明显且恢复较慢。在实验过程中平均血流速度（Ｖｍ） 没有显著变化。结论在推拉动作的－ Ｇｚ 时相由于脑血流的自调节机制引起脑血管阻力增加，在其后的＋ Ｇｚ 时相更为严重且恢复较慢。这可能是推拉效应＋ Ｇｚ 耐力下降的机制之一。
Objective To investigate the effect of push-pull on cerebrovascular circulatory function and the mechanism of + Gz decline in push-pull effect. Methods Ten subjects were subjected to simulated push and pull movements on a rotating bed in “upright position (+ 1Gz) - inverted position (-1Gz) - upright position (+ 1Gz)”, and the rotation was monitored by transcranial Doppler Changes of cerebral blood flow velocity and pulsatile parameters during bed motion simulation. Results In the upright position (-1Gz), there was an increase of systolic velocity (Vs), a decrease of diastolic velocity (Vd) and a rise of the pulsation parameters (PI) and (RI) These changes are more pronounced and slower to recover. The mean blood flow velocity (Vm) did not change significantly during the experiment. Conclusions The Gz phase of the push-pull motion causes an increase in cerebral vascular resistance due to the self-regulatory mechanism of cerebral blood flow, followed by a more severe and slower recovery of the + Gz phase. This may be one of the mechanisms by which the push-pull effect + Gz endurance drops.