HRV	Heart rate variability
MetS	Metabolic syndrome
ET	Endurance training
RT	Resistance training
HIIT	High-intensity interval training
CT	Concurrent training
STARD	Standard for Reporting Diagnostic Accuracy Studies
LF	Low-frequency (0.04–0.15 Hz)
HF	High-frequency (0.15–0.4 Hz)
VLF	Very-low frequency (<0.04 Hz)
TP	Total power
SDNN	Standard deviation of the R-R interval series
RMSSD	Root mean square of differences of successive R-R intervals