Abstract
Background: The autonomic nervous system (ANS), which governs practically all bodily processes, alters structurally and functionally as we age. Heart rate variability (HRV) studies are non-invasive, quantitative approaches to investigate the effects of ANS activity on the heart and also a marker to predict mortality.

Aim and Objectives: This study was undertaken to assess the effect of aging on cardiac sympathovagal activity in healthy males over seven decades using short-term HRV analysis.

Materials and Methods: This cross-sectional study was conducted on healthy in the age group of 10–69 years. Participants were divided into many age groups based on their decade of birth. Short-term HRV recording was done. In frequency domain analysis, spectral estimates of RR intervals was done by integrating the power as total power, low-frequency power (LF), high-frequency power (HF). In time-domain analysis, SDNN, RMSSD, and pNN50% were studied. Data were subjected to statistical analysis using ANOVA.

Results: In the frequency domain analysis of HRV, all the components such as total power, HF in nu and msec2, LF in nu and msec2, LF/HF ratio decreased as the age advances. In the time domain analysis of HRV, all the components decrease as age advances. When the values were compared with other age ranges, a significant decrease with aging only with respect to the comparisons between the youngest (10–29 years) and oldest (50–69 years) groups.

Conclusion: Our study found a global decrease in all the HRV indices. The decline in time domain indices was rapid in the early ages, stabilized out at the age of 40, and then declined gradually.

Key words: Heart Rate Variability; Autonomic Nervous System; Heart Rate Variability Indices