Table 2.
Variable | Definition | Interpretation |
---|---|---|
HR (bpm) | Heart rate mean | Overall variability of cardiac activity |
SDNN (ms) | Standard deviation of RR intervals | Long-term variability of cardiac activity influenced by the autonomous nervous system |
RMSSD (ms) | Square root of the mean of the sum of the squares of differences between successive interbeat-intervals (IBI) | High frequency of IBI variations correlated to parasympathetic activity |
LF/HF ratio | Low frequency/high frequency ratio | Representation of the balance between sympathetic and parasympathetic nervous systems |