Cardiovascular Control Mechanism during Head-down Bed Rest Using Nonlinear Techniques
Steven Vandeputa
LIU Jie-xin
LI Yong-zhi
CHEN Shan-guang
XIE Qiong
CHEN Zhang-huang
GAI Yu-qing
GAO Jian-yi
Sabine Van Huffela
Andre E Aubertb
Abstract：Objective To investigate the influence of -6°head-down bed rest(HDBR) on the cardiovascular control mechanism and effects of Chinese herbal medicine (CHM) as a countermeasure. Methods Fourteen Chinese healthy men were randomly allocated to a control group and a CHM group. Heart rate and blood pressure variability ( HRV & BPV) were assessed before, during and after 60 d HDBR with a focus on nonlinear techniques to quantify scaling behaviour, chaotic behaviour and complexity. Results There was no change in heart rate till the 21st day of HDBR, but increased significantly from the 41st day,without any recovery afterwards. DFA α1 was significantly higher on the 2nd day of HDBR compared with baseline and remained so high until even 12 d after HDBR. The chaos level was drastically lower during HDBR compared with the peri od before HDBR. Over all time sessions, heart rate, HRV 1/f slope and the BPV parameters SDNN, LF/HF,DFA α1 and 1/f were significantly higher in the control group compared with CHM group although HRV DFA α2 and BPV HF showed significantly lower values. Conclusion It confirmed the reduced vagal modulation and higher sympathovagal balance at the end of HDBR. Moreover, a change in nonlinear heart rate and blood pressure dynamics during HDBR was still present after 1 week of recovery. It demonstrates that CHM has restricted some influences of HDBR on the cardiovascular regulation, only partially functions as a countermeasure.
Keywords：head-down bed restheart rate variabilityautonomic nervous systemChinese herbal medicinenonlinear dynamics
Publication Date：2010-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)