Effect of 28-day head-down bed rest with countermeasures on heart rate variability during LBNP.
Effect of 28-day head-down bed rest with countermeasures on heart rate variability during LBNP.
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28 天低头卧床休息及对策对 LBNP 期间心率变异性的影响。
DOI：
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发表时间：
1994
影响因子：
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通讯作者：
C. Gharib
中科院分区：
文献类型：
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作者：
R. Hughson;Y. Yamamoto;A. Blaber;A. Maillet;J. Fortrat;A. Pavy;J. Marini;A. Güell;C. Gharib
通过研究连续6度头低位倾斜卧床休息前、期间（第15天）和28天后渐进式LBNP测试期间的心率变异性，评估了运动和LBNP对策对心血管去适应反应的影响。12名健康男性（年龄27-42岁）分为两组进行研究。6名被分配到一个对策方案（CM），包括剧烈的短期阻力运动，每天一次，每周6天，从第7天到第28天，结合下体负压（LBNP，-28毫米汞柱）15分钟，在第16，18，20和22-28天。结果进行了比较，从六个科目的数据，匹配的基础上最大摄氧量，谁没有收到对策（无CM）。卧床休息的主要影响是RR间期和总频谱功率的减少。频谱分析的结果表明，副交感神经活动的指数显着减少与交感神经指标的非显着增加。心率变异性的分形成分也减少了，表明心血管控制机制的变化。尽管CM和No-CM之间在许多变量上存在显著差异，但在统计分析中没有卧床休息与对策的相互作用效应。这些结果表明，这一特定系列的对策是无效的，至少在防止某些变化的心血管失调与28天头低位倾斜卧床休息。
The effect of exercise and LBNP countermeasures on the cardiovascular deconditioning response have been evaluated by the study of heart rate variability during progressive LBNP tests before, during (day 15), and after 28 d continuous 6 degrees head-down tilt bed rest. Twelve healthy men (age 27-42 years) were studied in two groups. Six were assigned to a countermeasure regime (CM) consisting of strenuous short-term resistance exercise once per day, 6 days per week from day 7 to day 28, combined with lower body negative pressure (LBNP, -28 mm Hg) for 15 min on days 16, 18, 20, and 22-28. Results were compared with data from six subjects, matched on the basis of maximum oxygen uptake, who received no countermeasures (No-CM). The main effects of bed rest were seen in reductions in RR-interval, and in total spectral power. The results of spectral analysis showed a significant reduction in an index of parasympathetic activity with a nonsignificant increase in a sympathetic indicator. The fractal component of heart rate variability was reduced also, suggesting a change in cardiovascular control mechanisms. Although there were significant differences between CM and No-CM for a number of variables, there were no bed rest by countermeasure interaction effects in the statistical analysis. These results suggested that this particular series of countermeasures was ineffective in preventing at least certain changes indicative of cardiovascular deconditioning with 28 d head-down tilt bed rest.