Table 3.
Intercorrelations between metrics of mean HR, overall HRV, cardiovagal control, and cardiac sympathetic activity.
| Mean HR | SDNN | CSI | RSA | RMSSD | pNN50 | HF-HRV | LF-HRV | HRDB | |
|---|---|---|---|---|---|---|---|---|---|
| Mean HR | — | ||||||||
| SDNN | −0.465** | — | |||||||
| CSI | 0.543** | −0.266* | — | ||||||
| RSA | −0.519** | 0.864** | −0.542** | — | |||||
| RMSSD | −0.590** | 0.867** | −0.609** | 0.841** | — | ||||
| pNN50 | −0.662** | 0.788** | −0.670** | 0.857** | 0.922** | — | |||
| HF-HRV | −0.252* | 0.822** | −0.344** | 0.737** | 0.815** | 0.679** | — | ||
| LF-HRV | −0.206* | 0.677** | 0.028 | 0.467** | 0.450** | 0.356** | 0.428** | — | |
| HRDB | 0.075 | 0.494** | −0.158 | 0.553** | 0.413** | 0.407** | 0.433** | 0.344** | — |
Note: Mean HR: mean heart rate; SDNN: standard deviation of interbeat interval (IBI); CSI: Toichi cardiac sympathetic index (sympathetic-related variability); RSA: natural log of variance of filtered (0.12–0.40 Hz) IBI; RMSSD: root mean square of successive differences between IBIs; pNN50: the percentage of the absolute differences between consecutive IBIs that are greater than 50 ms; HF-HRV: high frequency (HF)-heart rate variability (HRV) power (0.12–0.40 Hz); LF-HRV: low frequency (LF)-HRV power (0.04–0.12 Hz); HRDB: the HR response to deep breathing at 6 breaths per minute. *Indicates that Pearson's correlation is significant at P < 0.05. **Indicates that Pearson's correlation is significant at P < 0.001.