Effect of age and sex on heart rate variability in healthy subjects

Objective: The study aimed to investigate the effect of age and sex on the heart rate variability (HRV) analysis and to explore the normal range of HRV in different age and sex groups for potential health care applications. Method: Baseline HRV, age, and sex data were collected frorn 470 subjects without cardiovascular conditions. Short-tern HRV was recorded using Biocom Active ECG units (Biocom, Seattle, Wash). Subjects were divided by age into 10-year intervals and by sex for HRV analysis. Results: Total power, representing the overall autonomic activity, decreased consistently from the age groups 10+ to 80+ years (P <.001). Both the low frequency (sympathetic activity) and high frequency (parasympathetic activity) declined (P <.05) as age increased. Sex had a significant effect on heart rate, R-R interval, high frequency, normalized low frequency, nonnalized high frequency, and low frequency-high frequency ratio. Sex did not seem to affect the SD of the normal-to-normal heartbeats and total power (P >.05) despite the significant heart rate changes (P <.05). Conclusion: This study demonstrated that age had a greater impact on HRV than sex. The older age group had consistently lower HRV than younger people. The values generated in this study may be useful in health care settings to determine abnormal ranges of HRV under different clinical and experimental conditions.