I don't have ECG graphs and R-R peaks, but I need to calculate the HRV(heart rate variability). Is it possible to calculate this from the heart rate alone? How reliable would that be?
Heart rate variability (HRV) is a measure of the variation in the beat-to-beat interval. The heart rate (HR) is the number of heart beats in some unit time (generally expressed as the number of beats per minute). In general, because measures of HR are an average over time, it will smooth out the variability in the heart rate. The amount of HRV cannot be estimated from a measure of the HR at a single time point. Estimating the amount of HRV from multiple measures of HR at different times is possible, but will be corrupted by changes in the average heart rate over time. So in summary, no HRV cannot be estimated from measures of HR.