卧床不同训练方法对心血管自主神经调节变化的影响

Effects of Different Training Methods on Cardiovascular Autonomic Regulation during Bedrest.

目的以心率变异性 (HRV)频域变量 ,作为定量评价心血管自主神经调节变化的指标 ,观察卧床条件下 ,不同训练方法对心血管自主神经调节变化的影响。方法被试者为 1 5名年龄 1 9～ 2 2岁的健康男性 ,分为对照组、放松训练组和低氧训练组 ,每组 5人 ,头低位 (- 6°)卧床模拟失重时的心血管变化。在对照期 (第 2天 )、卧床期 (第 3、1 4、1 8天 )和恢复期 (第 7天 )记录 2 4h动态心电图 ,采用自回归模型进行 2 4h全程、放松和低氧训练前、中、后的心率变异性谱分析 ,其标准化的低频 (LF % ,0 .0 4～ 0 .1 5Hz)成分表示心交感神经的紧张度 ,标准化的高频 (HF % ,0 .1 5～ 0 .40Hz)成分独立地反映心迷走神经的活性 ,LF/HF的比值表明交感和迷走神经张力的平衡关系。结果卧床期对照组的LF %和HF %成分显著下降 (P <0 .0 5) ,LF/HF无明显变化。放松组在放松训练中HRV谱的HF %成分明显增加 (P <0 .0 5) ,而低氧组在低氧训练中 ,LF %成分显著增加 (P <0 .0 5)。结论卧床使交感和迷走神经的活性都降低 ,放松训练明显提高了迷走神经的兴奋性 ,而低氧训练明显提高了交感神经的兴奋性。提示 ,HRV指标有可能作为定量评价失重对抗措施的客观指标 ,值得进一步深入研究。

Objective To investigate the effects of different training methods on cardiovascular autonomic regulation under bedrest. Method 15 healthy male volunteers aged 19～22 participated tests in head down tilt (HDT) -6° bedrest in order to observe the changes of cardiovascular system under simulated weightlessness.They were divided into control (5 men),hypoxia training (5 men) and Fangsong training (5 men) groups.24 h dynamic ECG were recorded on the 2nd day of pre bedrest,on the 3rd,14th and 18th day of bedrest and on the 7 th day of the post bedrest.All spectra were estimated from entire 24 h HRV,before ,during and after Fangsong and hypoxia training by autoregressive (AR) modeling method.Normalized low frequency (LF %) was a quantitative marker of cardiac sympathetic activity,normalized high frequency (HF %) reflected the changes in cardiac vagal activity,and LF/HF was considered to be related to sympathovagal balance or sympathetic activity. Result In control group,LF% and HF% were all significantly reduced (P<0.05),LF/HL showed no significant changed during bedrest.In Fangsong group,HF% increased markedly (P<0.05),while in hypoxia group,LF% increased markedly (P<0.05). Conclusion Fangsong training counteracted markedly the reduction in vagal activity,while hypoxia training counteracted markedly the decrease in sympathetic activity.It was possible that HRV indices could be used to evaluate the efficiency of countermeasures counteracting the adverse effects of weightlessness.