Shvartz E, Gaume J G, White R T, Reibold R C
J Appl Physiol Respir Environ Exerc Physiol. 1983 Jun;54(6):1673-80. doi: 10.1152/jappl.1983.54.6.1673.
Eight young men (group A) underwent 5 h of quiet sitting, preceded by 30 min of recumbency, 20 min of standing, and 20 s of walking, and five other young men (group B) underwent 70 min of sitting, preceded by recumbency only, to determine the effects of prolonged sitting and previous posture on hemodynamic responses (measured by impedance plethysmography). Group A showed more calf blood pooling and a decrease in thigh blood flow during sitting in comparison with the control group, but after 1 h of sitting hemodynamic responses of the two groups were similar. Sitting for 5 h (1st vs. 5th h) resulted in an increase in calf venous pooling (17%) and a decrease in calf BF (13%), a reduction in gravitational pooling in the thigh (corresponding to increased pooling in the calf), increases in diastolic and mean arterial pressures (6 and 7.3 mmHg, respectively), and minor changes in heart rate, stroke volume, and cardiac output. The results show that it is necessary to sit for 1 h before hemodynamic responses can be assessed in this position, regardless of the posture maintained previously. The main effect of prolonged sitting is pooling in the calf, which is compensated for by an increase in peripheral resistance.
八名年轻男性（A组）先进行30分钟卧位、20分钟站立和20秒行走，然后静坐在5小时，另外五名年轻男性（B组）仅先进行卧位，然后静坐在70分钟，以确定长时间坐着和先前姿势对血流动力学反应（通过阻抗体积描记法测量）的影响。与对照组相比，A组在坐着期间小腿血液淤积更多，大腿血流量减少，但在坐着1小时后，两组的血流动力学反应相似。静坐5小时（第1小时与第5小时相比）导致小腿静脉淤积增加（17%），小腿血流量减少（13%），大腿重力性淤积减少（对应于小腿淤积增加），舒张压和平均动脉压升高（分别为6和7.3 mmHg），心率、每搏输出量和心输出量有轻微变化。结果表明，无论先前保持何种姿势，在该体位评估血流动力学反应之前，有必要先静坐1小时。长时间坐着的主要影响是小腿淤积，这通过外周阻力增加得到补偿。
