Definitions of the physiological parameters and their physiological relevance [25].
Name
Definitions and physiological relevance
Systolic blood pressure (SYS)
The blood pressure when the heart contracts to pump blood to the body, with a normal value ranging between 90 and 140
Diastolic blood pressure (DIA)
The blood pressure when the heart rests between beats, with a normal value ranging between 50 and 90
Pulse pressure
The gap between SYS and DIA, with a normal value being 30–50 mmHg
Number of heartbeats per minute (HR)
The average number of times the heart beats per min within 5 min
Number of occurrences of arrhythmia
Number of occurrences of arrhythmia within 5 min. If the value is >20, the participants should undergo a physical examination to understand the causes of the arrhythmia
Activity of the autonomic nervous system (HRV)
The variation in the time interval between heartbeats
LF power of the autonomic nerve system (LF)
Spectral power of LF R–R interval (0.04–0.15 Hz), which is related to the activity of parasympathetic nerves
HF power of the autonomic nerve system (HF)
Spectral power of HF R–R interval (0.15–0.4 Hz), which is related to the activity of parasympathetic nerves
LF power ratio of the autonomic nerve system (LF%)
Spectral power ratio of LF R–R interval. . The normal range is 30%–70%
Age of the autonomic nervous system activity (HRV age)
The age that the HRV data norm corresponds to. HRV decreases as age increases [19] (Figure 1)
