Normative Data on Heart Rate Variability Time and Frequency Domain Indices in a Healthy Central Indian Population Undergoing Treadmill Exercise

Background: Heart rate variability (HRV) is becoming one of the most valuable tools for assessing a healthy heart's complex and constantly changing oscillations. This study was a pioneering attempt to establish normative data on HRV during treadmill exercise for monitoring the cardiovascular health of the central Indian population.

Methodology: This was a cross-sectional study in the Sports Physiology Laboratory of the Department of Physiology in a Rural Medical College in central India. One hundred and twenty healthy subjects in the age range of 17-40 years were recruited. Short-term HRV (5 min) was extracted from ECG recordings obtained using the Power lab system, AD Instruments, Australia.

Results: Time domain indices for males were - Standard deviation of N-N interval (SDNN): 162.61±162.11; Square root of mean squared difference of N-N intervals (RMSSD): 355.79±798.27; the percentage of adjacent NN intervals that differ from each other by more than 50 ms (pNN50): 23.10±27.87. Frequency domain indices in males were- LF power (%)- 535.74±3625.96; HF power(%) - 33.15±24.31, LF nu: 33.12± 16.06 ; HF nu: 57.22±14.89; LF/HF: 0.77± 0.74. Time-domain indices for females were SDNN as 168.49± 130.09; RMSSD: 182.41± 154.85; pNN50: 32.33± 26.59. Frequency domain indices in females were LF power (%)-19.85± 6.13; HF power (%) 43.03± 16.39, LF nu- 30.53± 9.88; HF nu - 60.95± 8.70; LF/HF: 0.54± 0.27

Conclusion: Baseline normative values for HRV spectral and time-domain analysis have been established for their clinical use in comparing the HRV of a healthy individual to that of a deceased individual or an athlete.