Hughes L O, Heber M E, Lahiri A, Harries M, Raftery E B
Department of Cardiology, Northwick Park Hospital, Harrow, Middlesex, U.K.
Eur Heart J. 1989 Oct;10(10):896-902. doi: 10.1093/oxfordjournals.eurheartj.a059399.
A nuclear probe was used to assess beat-to-beat changes in relative cardiac output in eight elite athletes during isometric exercise. Three subjects underwent simultaneous intra-arterial blood pressure recording. Stroke volume fell by 68 +/- 4% during Valsalva's manoeuvre alone, but by 42 +/- 9% with simultaneous isometric handgrip. Blood pressure changes during isometric handgrip were significantly modified by simultaneous Valsalva's manoeuvre. In particular no late strain phase fall or post-strain overshoot in blood pressure was seen, hence there was no baroreceptor-mediated fall in heart rate. Maximum Valsalva's manoeuvres in athletes invoked extreme falls in cardiac output and blood pressure which were attenuated by simultaneous isometric handgrip. The mechanism of this may be twofold: increased venous tone maintains stroke volume; and/or increased arteriolar tone maintains blood pressure.
使用核探针评估了8名优秀运动员在等长运动期间逐搏相对心输出量的变化。3名受试者同时进行了动脉内血压记录。仅在瓦尔萨尔瓦动作期间，每搏输出量下降了68±4%，但在同时进行等长握力运动时下降了42±9%。等长握力运动期间的血压变化因同时进行瓦尔萨尔瓦动作而显著改变。特别是未观察到血压的晚期应变期下降或应变后过冲，因此不存在压力感受器介导的心率下降。运动员进行最大瓦尔萨尔瓦动作时会引起心输出量和血压的极度下降，而同时进行等长握力运动可使其减弱。其机制可能有两方面：静脉张力增加维持每搏输出量；和/或小动脉张力增加维持血压。
