提踵动作对下体负压耐力的影响

目的验证提踵动作对提高下体负压耐力的有效性,并探讨其可能的作用机制。方法健康男性志愿者10名,在下体负压(LBNP)条件下分别随机进行2次头高位倾斜检查(HUT)测定其下体负压耐力。一次为志愿者的基础下体负压耐力(对照组),另外一次要求志愿者在LBNP条件下做提踵动作,直至耐力终点(提踵组)。结果提踵组下体负压耐受时间(DNP)和累计应激指数(CSI)均显著增加(P<0.05)。在下体负压过程中,提踵组平均动脉压呈升高趋势,心率增加呈降低趋势,每搏量增加,且均在-40 mmHg及-50 mmHg时达到显著水平(P<0.05)。结论提踵动作可以提高下体负压耐力,可望作为航天员在长期太空飞行后引起立位耐力不良时的应对措施,也可作为血管迷走性晕厥患者的预防措施和治疗手段。

Changes of Lower Body Negative Pressure Tolerance with and without Heel Rising

Objective To verify the effectiveness of heel rising on orthostatic tolerance and to explore its possible mechanism.Methods Ten healthy male subjects underwent orthostatic stress tests of combined head-up tilt and lower body negative pressure(LBNP)on two separate days.One test was used to determine the baseline LBNP tolerance(control group).While in the other test,subjects were instructed to perform heel raising 10 s at the onset of LBNP,then rest 20 s and repeated until presyncope or syncope.Results As compared with those of control group,the duration of negative pressure and cumulative stress index(CSI)increased(P<0.05) when heel raising was conducted.Mean arterial pressure and stroke volume increased significantly(P<0.05) and increment of heart rate lowered significantly during LBNP of-40 mmHg and-50 mmHg phase(P<0.05).Conclusion Heel rising can increase human LBNP tolerance.It might be useful in preventing occurrence of syncope in astronauts after long term spaceflight or patients with vasovagal syncope.