Correlation matrix of heart rate variability parameters
| Variables | MRR | SDNN | RMSSD | pNN50 | LF | HF | LF/HFNormlog |
|---|---|---|---|---|---|---|---|
| MRR | 1.00 | 0.41 | 0.51 | 0.56 | –0.43 | 0.43 | –0.46 |
| SDNN | 0.41 | 1.00 | 0.96 | 0.78 | –0.55 | 0.55 | –0.55 |
| RMSSD | 0.51 | 0.96 | 1.00 | 0.87 | –0.67 | 0.67 | –0.68 |
| pNN50 | 0.56 | 0.78 | 0.87 | 1.00 | –0.73 | 0.71 | –0.73 |
| LF | –0.43 | –0.55 | –0.67 | –0.73 | 1.00 | –0.99 | 0.99 |
| HF | 0.43 | 0.55 | 0.67 | 0.71 | –0.99 | 1.00 | –0.98 |
| LF/HFNormlog | –0.46 | –0.55 | –0.68 | –0.73 | 0.99 | –0.98 | 1.00 |
Values are Pearson’s correlation. Strong positive correlations and strong negative correlations (above 0.8) are shown in dark black. MRR is the mean of the normal sinus (NN) intervals; SDNN is the standard deviation (SD) of all NN intervals; RMSSD is the root mean square of the successive differences between adjacent NN intervals; pNN50 is the percentage of times that the change in consecutive NN sinus intervals exceeded 50 ms; LF is low frequency; HF is high frequency, and LF/HFNormlog is normalized LF/HF by logarithmic transformation