Department of Physiology, University of Otago, Dunedin, New Zealand.
Exp Gerontol. 2011 Jan;46(1):9-17. doi: 10.1016/j.exger.2010.06.005. Epub 2010 Jun 30.
The purpose of this study was to examine the combined cardiorespiratory and cerebrovascular responses to head-up tilt (HUT) in young (27 ± 4 years) and older (65 ± 5 years) trained and untrained humans. Middle cerebral artery blood velocity (MCAv; transcranial Doppler ultrasound), blood pressure (BP; Finometer) and cardiac output (Q) were measured continuously whilst supine and during 60° HUT for 15 min or to pre-syncope in 41 participants [nine young trained; eleven young untrained; twelve older trained; nine older untrained]. Thirty seven of forty one participants completed 15 min HUT, and orthostatic tolerance did not differ with age or fitness (P = 0.66). Supine MCAv was 30% lower in the older participants but the HUT-induced drop in MCAv was not altered by age [-18% (young) vs. -17% (older)], or fitness. Mean arterial BP was maintained during HUT and not altered by age or fitness. In the untrained, peripheral resistance was elevated [11% vs. -2% (trained); P = 0.01], and Q was reduced [-10% vs. -5% (trained); P = 0.04] with HUT. Despite these age- and fitness-associated differences in some cardiovascular responses to HUT, orthostatic tolerance was similar across groups. Thus, at least in this healthy population, neither age nor fitness impacts on the ability to adapt to postural change.
本研究旨在探讨年轻（27 ± 4 岁）和老年（65 ± 5 岁）训练有素和未经训练的人体在头高位倾斜（HUT）下心肺和脑血管的综合反应。在 41 名参与者中，连续测量大脑中动脉血流速度（MCAv；经颅多普勒超声）、血压（BP；Finometer）和心输出量（Q），平卧位和 60°HUT 持续 15 分钟，或在 41 名参与者中出现预晕厥。[9 名年轻训练组；11 名年轻未训练组；12 名老年训练组；9 名老年未训练组]。四十一名参与者中有三十七分完成了 15 分钟的 HUT，体位耐受性不因年龄或健康状况而有差异（P = 0.66）。老年人的 MCAv 在平卧位时降低了 30%，但 HUT 引起的 MCAv 下降不受年龄[年轻组-18%（年轻）vs. 老年组-17%（老年）]或健康状况的影响。HUT 期间平均动脉压保持不变，不受年龄或健康状况的影响。在未经训练的人群中，外周阻力升高[年轻组 11%vs. 训练组-2%；P = 0.01]，心输出量降低[年轻组-10%vs. 训练组-5%；P = 0.04]。尽管 HUT 对一些心血管反应存在与年龄和健康相关的差异，但各组之间的体位耐受性相似。因此，至少在这个健康人群中，年龄和健康状况都不会影响对体位变化的适应能力。
