Properties and Modification of Bismuth-Layered Structure Ferroelectric Materials and Application in Sports

Table 5

The experimental group did not apply hyperbaric oxygen for two weeks during the observation period to restore the changes in heart rate variability.

Heart rate variability index	First week of observation period	Second week of observation period
SDNN	85.12	70.80
RMSSD	85.65	81.54
PNN50	22.04	19.99
VLF	305.77	209.38
HF	165.13	1095.35
LF	817.80	537.79
HF/LF	1.17	1.35