HRV can be measured using various techniques, including electrocardiography (ECG) and wearable devices like fitness trackers and smartwatches. These tools analyze the time intervals between successive R-waves (the peaks in the ECG signal) to calculate HRV. Common metrics used to assess HRV include the standard deviation of normal-to-normal intervals (SDNN) and the root mean square of successive differences (RMSSD).
