Stachenfeld N S, Mack G W, DiPietro L, Morocco T S, Jozsi A C, Nadel E R
Department of Epidemiology, Yale University School of Medicine, New Haven, CT 06519, USA.
Med Sci Sports Exerc. 1998 Jan;30(1):92-8. doi: 10.1097/00005768-199801000-00013.
In younger people the increase in aerobic capacity following training is related, in part, to blood volume (BV) expansion and the consequent improvements in maximal cardiac output. This training-induced hypervolemia is associated with a decrease in cardiopulmonary baroreflex (CPBR) control of peripheral vascular tone.
To test the hypothesis that improvement in peak oxygen consumption (VO2peak) during training in older women is associated with specific central adaptations, such as BV expansion and a reduction in CPBR control of vascular tone.
Seventeen healthy older women were randomized into training (N = 9, 71 +/- 2 yr) and control (N = 8, 73 +/- 3 yr) groups. The training group exercised three to four times per wk for 30 min at 60% peak heart rate for 12 wk and then 40-50 min at 75% peak heart rate for 12 wk. The control group participated in yoga exercises over the same time period. We measured resting BV (Evans blue dye), VO2peak, and the forearm vascular resistance response to unloading low pressure mechanoreceptors during low levels of lower body negative pressure (through -20 mm Hg) before and after aerobic training. The slope of the increase in forearm vascular resistance (response) per unit decrease in central venous pressure (stimulus) was used to assess CPBR responsiveness.
Aerobic training increased VO2peak 14.2% from 24.2 mL x kg(-1) x min(-1) to 27.7 mL x kg(-1) x min(-1) (P < 0.05), a smaller improvement than typically seen in younger subjects. Blood volume (59.9 +/- 1.9 and 60.9 +/- 1.9 mL x kg[-1]) and CPBR function (-3.98 +/- 0.92 and -3.46 +/- 0.94 units x mm(-1) Hg) were similar before and after training.
These data indicate that the inability to induce adaptations in CPBR function may limit BV expansion during training in older women. In addition, the absence of these specific adaptations may contribute to the relatively poor improvements in VO2peak in older women during short (10-12 wk) periods of training.
在年轻人中，训练后有氧能力的提高部分与血容量（BV）增加以及随之而来的最大心输出量改善有关。这种训练诱导的血容量过多与心肺压力反射（CPBR）对外周血管张力的控制降低有关。
检验以下假设，即老年女性训练期间峰值摄氧量（VO2peak）的改善与特定的中枢适应性变化有关，如血容量增加和CPBR对血管张力控制的降低。
将17名健康老年女性随机分为训练组（N = 9，71±2岁）和对照组（N = 8，73±3岁）。训练组每周进行三到四次运动，前12周以心率峰值的60%运动30分钟，然后在接下来的12周以心率峰值的75%运动40 - 50分钟。对照组在同一时间段内参加瑜伽练习。我们在有氧训练前后测量静息血容量（伊文思蓝染料法）、VO2peak以及在低水平下体负压（-20 mmHg）期间卸载低压机械感受器时前臂血管阻力的反应。用每单位中心静脉压下降（刺激）时前臂血管阻力增加（反应）的斜率来评估CPBR反应性。
有氧训练使VO2peak从24.2 mL·kg⁻¹·min⁻¹增加了14.2%，达到27.7 mL·kg⁻¹·min⁻¹（P < 0.05），改善程度小于年轻受试者通常所见。训练前后血容量（59.9±1.9和60.9±1.9 mL·kg⁻¹）和CPBR功能（-3.98±0.92和-3.46±0.94单位·mmHg⁻¹）相似。
这些数据表明，老年女性训练期间无法诱导CPBR功能适应可能会限制血容量增加。此外，缺乏这些特定适应可能导致老年女性在短时间（10 - 12周）训练期间VO2peak改善相对较差。
