Table 1 HRV parameters and their physiological association
Parameter | Abbreviation | Physiological association |
|---|---|---|
Time domain | ||
 Standard deviation of NN intervals | SDNN | Overall HRV, sympathetic and parasympathetic innervation |
 Root mean square of successive difference between NN intervals | RMSSD | Short-term HRV, primarily parasympathetic innervation |
Frequency domain | ||
 Total power | TP | Total HRV (as the band encompasses all frequencies) |
 High frequency | HF | Parasympathetic control |
 Ratio high frequency and total power | HF/TP | Parasympathetic control |
 Intermediate frequency | IntF | Sympathetic and parasympathetic arm of the ANS |
 Low frequency | LF | Sympathetic and parasympathetic arm of the ANS |
 Very low frequency | VLF | Sympathetic control |
 Ratio very low frequency and high frequency | VLF/HF | Sympatho-vagal balance |
 Ratio very low frequency and low frequency | VLF/LF | Sympatho-vagal balance |
 Ratio low frequency and high frequency | LF/HF | Sympatho-vagal balance |