Table 1 Description of extracted HRV parameters
Variable | Units | Description | Indicator of … |
|---|---|---|---|
SDNN | ms | Standard deviation of all NN intervals | total variability |
RMSSD | ms | Square root of the mean of the sum of the squares of differences between adjacent NN intervals | short-term variability |
NN50 count |  | Number of pairs of adjacent NN intervals differing by more than 50 ms in the entire recording | spontaneous variability |
pNN50 | % | NN50 count divided by the total number of all NN intervals | spontaneous variability |
LF | ms2 | Power in low frequency range (≤ 0.04 Hz) | sympathetic and parasympathetic, but predominantly sympathetic |
HF | ms2 | Power in high frequency range (0.15–0.4 Hz) | parasympathetic |
LF nu |  | LF power in normalised units LF/(Total Power–VLF) × 100 | sympathetic and parasympathetic, but predominantly sympathetic |
HF nu |  | HF power in normalised units HF/(Total Power–VLF) × 100 | parasympathetic |
LF/HF | Â | Ratio LF [ms2]/HF [ms2] | sympathetic and parasympathetic |
TP | ms2 | Total performance or total spectrum; corresponds to energy density between 0.00001 to 0.4 Hz | total variability |
SD1 | ms | Standard deviation of instantaneous beat-to-beat variability, extracted from Poincaré Plot | parasympathetic |
SD2 | ms | Standard deviation of the long-term variability, extracted from Poincaré Plot | sympathetic and parasympathetic |