Table 1.

Results of heart rate variability analysis (Mean ± Standard Deviation).

Variable/Group	Baseline	−3%	−5%	−10%
Mean HR	70.38 ± 6.84	68.44 ± 7.25	67.42 ± 7.67	67.54 ± 3.91
pNN50	7.11 ± 4.20	9.22 ± 7.64	9.52 ± 7.03	11.89 ± 6.25
SDNN	58.41 ± 11.03	56.19 ± 18.36	58.90 ± 18.41	61.01 ± 15.89
RMSSD	38.15 ± 13.97	38.65 ± 17.20	39.95 ± 15.64	46.26 ± 18.12
nLF	0.63 ± 0.10	0.56 ± 0.10 a	0.58 ± 0.10	0.55 ± 0.15
nHF	0.37 ± 0.10	0.44 ± 0.10 a	0.42 ± 0.10	0.45 ± 0.15
LF/HF	2.30 ± 1.10	1.84 ± 1.04 b	1.81 ± 0.83	1.75 ± 1.04

HR—heart rate; pNN50—percentage of successive NN intervals that differ by more than 50 ms; SDNN—standard deviation of the NN intervals; RMSSD—root mean square of the successive NN interval differences; nLF—normalized low-frequency band power; nHF—normalized high-frequency band power; LF/HF—ratio of the low-frequency power to the high-frequency power. Values that were significantly different between the baseline and stimulation conditions are shown in bold. a: p < 0.03 between the baseline and −3% stimulation conditions, b: p < 0.01 between the baseline and −3% stimulation conditions (Wilcoxon rank-sum test).