Smith M L, Raven P B
Med Sci Sports Exerc. 1986 Oct;18(5):545-50.
The cardiovascular responses to lower body negative pressure (LBNP) (to -50 torr) were examined in 8 sedentary control (UT), 8 endurance-trained (ET), and 8 weight-trained (WT) human subjects. The results were used to compare and contrast the blood pressure control system of the three subject groups. The primary differences in response included a more effective maintenance of blood pressure, by reason of greater stroke volume and cardiac indices of the WT subjects during LBNP (P less than 0.05). Peripheral vascular resistances were not different (P greater than 0.05) throughout LBN P between the three groups. Therefore, the improved blood pressure maintenance of the WT subjects was attributed to a cardiac effect. The ET subjects were less effective in maintaining blood pressure than UT or WT subjects. This finding was apparently due to an attenuated baroreflex sensitivity, as evidenced by a significantly (P less than 0.05) lower delta heart rate/delta systemic blood pressure ratio, 0.99 for ET vs 1.51 and 1.38 or the UT and WT groups respectively, calculated from the responses observed from 0 to -50 torr of LBNP.
对8名久坐不动的对照组（UT）、8名耐力训练组（ET）和8名力量训练组（WT）的人类受试者进行了下体负压（LBNP，至-50托）下的心血管反应检查。结果用于比较和对比这三组受试者的血压控制系统。反应的主要差异包括，由于WT组受试者在LBNP期间有更大的每搏输出量和心脏指数，其血压维持更有效（P<0.05）。在整个LBNP过程中，三组之间的外周血管阻力无差异（P>0.05）。因此，WT组受试者血压维持的改善归因于心脏效应。ET组受试者在维持血压方面不如UT组或WT组有效。这一发现显然是由于压力反射敏感性减弱，从LBNP 0至-50托的反应计算得出，ET组的心率变化/全身血压变化比值显著更低（P<0.05），ET组为0.99，而UT组和WT组分别为1.51和1.38。
