Abstract
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 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 as168.49±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.