Table 2.
HRV and respiration variables in our software system for stress assessment and biofeedback application [31].
| Variable | Unit | Description |
|---|---|---|
|
| ||
| Selected Time Domain Measures of HRV (or PRV) | ||
| SDNN | ms | Standard deviation of all RR intervals |
| rMSSD | ms | The square root of the mean of the sum of the squares of differences between adjacent RR intervals |
| Selected Frequency Domain Measures of HRV (or PRV) | ||
|
| ||
| Total Power (TP) | ms2 | The variance of RR intervals over the temporal segment (≤0.4 Hz) |
| LF norm | nu | Low frequency (LF, 0.04–0.15 Hz) power in normalized units |
| HF norm | nu | High frequency (HF, 0.15–0.4 Hz) power in normalized units |
| LF/HF | % | Ratio LF norm[nu]/HF norm[nu] |
| Selected Respiratory Measures | ||
|
| ||
| Breathing Rate | b/m | Average breathing rate per minute in respiration recordings |
| Inspiration time | s | Relative time ofinspiration within respiration cycle |
| Expiration time | s | Relative time ofexpiration within respiration cycle |