Savard G K, Stonehouse M A
School of Physical and Health Education, Queen's University, Kingston, Ontario.
Can J Appl Physiol. 1995 Jun;20(2):240-54. doi: 10.1139/h95-018.
The effects of exercise training posture on cardiovascular and baroreflex responses to orthostatic challenge were assessed in highly trained cyclists (CT, n = 8) and swimmers (ST, n = 8), and in untrained men (UT, n = 8). CT demonstrated the lowest orthostatic tolerance to lower body negative pressure (LBNP, 0 to -50 mmHg), with only 3 subjects completing the full LBNP procedures; 5 UT and all ST completed the testing. During LBNP, stroke volume (SV) decreases were similar in CT and ST, but greater than in UT. Mean pulse pressure and systemic vascular resistance (SVR) were reduced in CT relative to ST and UT at the highest levels of LBNP; the slope of the delta SVR/delta Zo and delta SVR/delta SV relationships in CT, used to assess peripheral vascular baroreflex function, were attenuated relative to the other groups. There were no between-group differences in the heart rate response to LBNP. The greater incidence of orthostatic intolerance observed in upright-versus supine-trained athletes during passive LBNP was linked to attenuated baroreflex control of peripheral vascular resistance.
在训练有素的自行车运动员（CT组，n = 8）、游泳运动员（ST组，n = 8）和未经训练的男性（UT组，n = 8）中，评估了运动训练姿势对直立应激时心血管和压力反射反应的影响。CT组对下体负压（LBNP，0至-50 mmHg）的直立耐受性最低，只有3名受试者完成了完整的LBNP程序；5名UT组受试者和所有ST组受试者完成了测试。在LBNP期间，CT组和ST组的每搏输出量（SV）下降相似，但大于UT组。在LBNP的最高水平时，CT组的平均脉压和全身血管阻力（SVR）相对于ST组和UT组降低；用于评估外周血管压力反射功能的CT组中SVR变化量/ Zo变化量和SVR变化量/SV变化量关系的斜率相对于其他组减弱。在对LBNP的心率反应方面，各组之间没有差异。在被动LBNP期间，直立训练与仰卧训练的运动员中观察到的直立不耐受发生率较高，与外周血管阻力的压力反射控制减弱有关。
