Objectives: The aim of this study was to evaluate the effect of the supine, left lateral decubitus, and right lateral decubitus positions on autonomic nervous activity in elderly adults by using spectral analysis of heart rate variability (HRV). Method: Forty-five adults aged 73.6 ± 5.7 years were enrolled. After lying in the supine position, all participants moved to the lateral decubitus positions in a random order and maintained the positions for 10 min, while electrocardiographic data were recorded to measure HRV. Results: The lowest heart rate continued for 10 min when participants were in the left lateral decubitus position compared with the other two positions (p < .001), while the HRV indexes remained unchanged. The low-frequency HRV to high-frequency HRV ratio (LF/HF) for the right lateral decubitus position was significantly lower than that for the other positions. Discussion: The right lateral decubitus position may attenuate sympathetic nerve activity in elderly adults.
PurposeThe aim of the study was to investigate the effects of the menstrual cycle on exercise performance and cardiovascular responses in female long‐distance runners.MethodsFifteen well‐trained female long‐distance runners aged 19.4±1.1 years were monitored for basal body temperature (BBT), systolic and diastolic blood pressure (SBP, DBP) and heart rate (HR) every morning for 2 months. They also recorded their menstrual periods, and ratings of perceived exertion (RPE) as exercise performance during the menstrual phase, the follicular phase, and the luteal phase.ResultSeven runners had normal menstrual cycle (NMC). Eight runners had abnormal menstrual cycle (AMC), including polymenorrhea (n = 2), oligomenorrhea (n = 3) and amenorrhea (n = 3). SBP, DBP, and RPE were significantly higher in the menstrual phase than in the follicular phase in runners with NMC, whereas SBP and DBP did not change significantly during the menstrual cycle in those with AMC. SBP and DBP tended to be higher in the luteal phase than in the follicular phase in runners with NMC. HR did not change significantly during the menstrual cycle in either group.ConclusionA large number of female long‐distance runners appear to have menstrual disturbances, and increased SBP and DBP in the menstrual phase may negatively influence exercise performance.
Some studies have reported that recumbent position may have advantages in patients with heart disease and in pregnancy. However, it remains controversial whether recumbent position affects autonomic nervous system activity and hemodynamics in healthy adults. The aim of this study was to evaluate alterations in heart rate variability (HRV) and hemodynamics in the supine, left recumbent and right recumbent positions in healthy young adults. A total of 80 participants aged 22.8 ± 3.1 years were enrolled in this observational study. Fifty-eight volunteers (29 men and 29 women) maintained the supine position followed by the left and right recumbent positions, while electrocardiographic data were recorded for spectral analysis of HRV to assess cardiac vagal nerve and sympathetic nerve activities. The heart rate (HR) was significantly lower in the left recumbent position than in the other positions. There were no statistically significant differences in HRV among the three positions. Considering the possibility that the echographic procedure affects autonomic nervous system (ANS) activity, the other 22 participants (11 men and 11 women) underwent an echographic evaluation of hemodynamics in the heart and inferior vena cava (IVC) across the three positions. Although a low HR was also observed, there were no statistically significant differences in the IVC or the heart blood volume between the supine and the left recumbent positions. A postural change to the left recumbent position does not affect the cardiac blood circulation or ANS activity, though it does decrease HR in healthy young adults. This finding indicates that the lower HR in the left recumbent position is not attributable to the ANS activity.
The aim of this study was to investigate the effect of blood volume reduction (300 – 400 mL) on circulation and Heart Rate Variability (HRV), by using autologous blood donation as a model of blood volume change. In 33 adult subjects (56.3 ± 15.9yrs) with no circulatory, respiratory, or neurologic disease, we measured Blood Pressure (BP) and electrocardiographic parameters during autologous blood donation. We divided the subjects into 3 groups according to age (10–30 yrs, 40–50 yrs, and 60–80 yrs) and into 2 groups according to blood donation experience. In all age groups, the Low‐Frequency power/High‐Frequency power ratio (LF/HF) increased, and the HF power decreased during autologous blood donation. Additionally, during autologous blood donation, the 60–80 yrs age group exhibited the highest variation in HRV. In non‐experienced group, LF/HF decreased after autologous blood donation. Further, 1 subject developed Vaso‐Vagal Reaction (VVR). LF/HF was markedly higher in this subject than in the other subjects before autologous blood donation. After autologous blood donation, the decrease in LF/HF in the subject with VVR was similar that of subjects in the non‐experienced group. In the subject with VVR, BP decreased significantly, and the Heart Rate (HR) did not increase after autologous blood donation. In contrast, in the other subjects, BP decreased mildly and HR increased after autologous blood donation.
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