30d头低位卧床期间下肢运动锻炼对心脏功能的影响

Effects of Lower Limb Exercise on Cardiac Function during 30 d Head-down Tilt Bed Rest.

目的本实验利用头低位卧床模拟失重,通过观察和比较30 d卧床期间不同体育锻炼方式对心脏收缩泵血功能的影响,旨在进一步明确体育锻炼对失重后心脏功能变化的对抗效果,为制定我国载人航天时航天员失重对抗方案提供实验依据。方法15名男性健康被试者,随机分为对照组、下肢肌力训练组和自行车功率计训练组3组,每组5人。对照组仅-6°HDT卧床30 d,不进行任何处理,下肢肌力训练组和自行车功率计训练组在30 d卧床期间分别进行下肢肌力训练和自行车功率计训练。实验期间测量心脏收缩泵血功能的变化。结果对照组左室射血时间在卧床第22、26天较卧床前显著降低(P<0.05),射血分数在第26天显著性降低(P<0.05),每搏量、心输出量在第1天显著降低(P<0.05)。下肢肌力训练组左室射血时间在卧床期间较卧床前均显著降低(P<0.05),每搏量除第5、7天外均显著降低(P<0.05),心输出量在第1、30天显著降低(P<0.05)。自行车功率计训练组心脏收缩功能指标在卧床期间均无明显变化,每搏量、心输出量在卧床第1天较卧床前显著降低(P<0.05)。结论30 d头低位卧床可引起心脏收缩泵血功能下降,下肢肌力训练和自行车功率计训练可在一定程度上改善心血管功能,其中自行车功率计训练的对抗效果更佳。

Objective To observe and compare the effects of exercise on the cardiac function during 30 d headdown tilt （HDT） bed rest, and to see if these protocols would positively affect cardiac function. Methods Fifteen healthy male volunteers were randomly divided into control group, lower limb muscular exercise group and bicycle ergometrie exercise group, with 5 in each group. The subjects in the control group only performed -6° HDT bed rest for 30 d. The subjects in the lower limb muscular exercise group performed exercise with a lower limb muscular exercise and the subjects in the bicycle ergometric exercise group performed exercise with a bicycle ergometric exercise during HDT bed rest. The cardiac systole and pump functions were measured before, during and after HDT bed rest in three groups. Results Compared with pre-HDT, left ventricular ejection time （LVET） decreased significantly （P 〈0.05） in the 22nd day and the 26th day of HDT, ejection fraction （EF） decreased （P 〈0.05） in the 26th day of HDT, stroke volume （SV） and cardiac output （CO） decreased （P 〈 0.05 ） in the 1 st day of HDT in control group. Compared with pre-HDT, LVET in limb muscular group decreased significantly （P 〈 0.05） throughout HDT, SV decreased （P 〈 0.05 ） in all time except the 5th day and the 7th day of HDT, CO decreased （P〈0.05） in the 1st day and the 30th day of HDT. Compared with pre-HDT, the indexes of cardiac systole function in bicycle ergometric group had no significant changes, SV and CO decreased （ P 〈 0.05 ） in the 1 st day of HDT. Conclusion The cardiac systole and pump functions decrease significantly during 30 d HDT bed rest. The limb muscular exercise and the bicycle ergometric exercise may improve the cardiovascular system to some extent. Further, the bicycle ergometric exercise is the better one.