ANS	Autonomic nervous system
BP	Blood pressure
ECG	Electrocardiogram
HF	High-frequency band
HRV	Heart rate variability
LF	Low-frequency band
LF/HF	Ratio of low- and high-frequency bands
NNmax	Longest normal heart cycle during the measured period
NNmean	Average length of normal heart cycles during the measured period
NNmin	Shortest normal heart cycle during the measured period
PHY	Physical stress test
pNN50	Ratio of consecutive NN interval pairs with a greater difference than 50 ms
PSY	Psychological stress test
PTSD	Post-traumatic stress disorder
rMSSD	Root mean square of successive differences
SDNN	Standard deviation of normal heart cycles during the measured period
TP	Total power
VLF	Very-low-frequency band
VO2peak	Peak oxygen uptake