Sex differences in heart rate variability and circulation after postural change (1073.3)

Abstract

It is well known that sex differences in body weight, blood pressure (BP) and heart rate (HR) exist. However, little research has been conducted on sex differences in circulatory effects, including autonomic nervous activity, between various recumbent positions. This study aimed to evaluate whether male and female young adults show differences in circulatory effects and autonomic nervous activity between 3 positions (supine, right lateral, and left lateral decubitus). Twenty‐nine male (22.5 ± 0.5 years) and 29 female (23.1 ± 0.7 years) healthy volunteers participated in this study. We measured HR variability (HRV) and BP in each of the 3 positions for 10 min. Compared to females, males had a significantly higher systolic BP and low frequency‐to‐high frequency component ratio (LF/HF) in all 3 positions. In females, HF was significantly higher than that in males in the right and left lateral decubitus positions. In both sexes, HR was significantly decreased in the left lateral decubitus position compared to the supine position. Interestingly, neither sex showed significant changes in HF and LF/HF during the change from the supine position to the recumbent positions. The results suggest that there are differences in baseline autonomic nervous activity between males and females. However, both sexes have same reaction to postural changes in circulatory dynamics.